FROM  THE  LIBRARY  OF 


WILLIAM   DUNCAN   McKIM 

GRADUATE  OF 

COLUMBIA  UNIVERSITY 

A.  B.,  1875;  A.  M.,  1878;  M.  D.,  1878 


Q?3^ 


CoUcge  of  S^i^^^icim^  anij  burgeon* 
Hibvavp 


A    MANUAL 


HUMAN    PHYSIOLOGY. 


-^yUik^ 


(UJUl^ 


A    MANUAL    OF 

HUMAN    PHYSIOLOGY, 


INCLUDING 


HISTOLOGY  AND  MICROSCOPICAL  ANATOMY; 

WITH   SPECIAL  REFERENCE  TO   THE  REQUIREMENTS  OP 

PRACTICAL     MEDICINE. 


BY 

DR.    L.    L  A  N  D  O  I  S, 

PROFESSOR  OF  PHYSIOLOGY  AND   DIRECTOR  OF  THE  PHYSIOLOGICAL  INSTITUTE, 
UNIVERSITY  OF  GREIFSWALD. 


TRANSLATED    FROM    THE    FOURTH    GERMAN   EDITION. 


WITH  ADDITIONS   BY 

WILLIAM     STIRLING,    M.D.,    Sc.D., 

REGIUS  PROFESSOR  OF  THE  INSTITUTES  OF  MEDICINE  OR  PHYSIOLOGY  IN  THE  UNIVERSITY  OF  ABERDEEN, 


■WIXH     17S     IXjLXTSTE.^TlOIsrS- 


VOL.    I. 


PHILADELPHIA: 

P.    BLAKISTON,    SON,    AND    COMPANY, 

I0I2    WALNUT     STREET. 

1885. 

\All  Eights  Reserved.] 


V' 


TO 

SIR   JOSEPH   LISTER,    Baronet, 

M.D.,  D.C.L.,  I,t.D.,  F.K.SS.    (LOSD.  ASD  EDIS.), 

PROFESSOE  OF  CLINICAL  SUEGEEY  IN  KING'S  COLLEGE,  LONDON,  SUEGEON-EXTRAOBDINABT  TO  THE  QCEEN; 

FOEMBBIT  REGIUS  PK0FES30E  OF  CLINICAL  SUEGEEY  IS  THE  UNIVEKSITT  OF  EDINBCEGH. 

IN"  ADMIRATION   OF 

%lsz  Pan  xrf  ^^xiena, 

WHOSE   BRILLIANT   DISCOVERIES   HAVE  REVOLUTIONISED 

MEDICAL    PRACTICE,     AND    CONTRIBUTED    INCALCULABLY    TO    THE 

WELL-BEING  OF  MANKIND; 

AND     IN     GRATITUDE     TO 

WHOSE  NOBLE  EARNESTNESS  IN  INCULCATING 

THE  SACREDNESS  OF  HUMAN   LIFE 

STIRRED     THE     HEARTS     OF    ALL    WHO    HEARD     HIM: 

cTlus  Morii  IS  rcspcttfuUjr  5cbi:at£j> 

BY   HIS   FORMER  PUPIL, 

THE    TRANSLATOR. 


PEEFACE. 


The  fact  that  Professor  Landois'  " Lehrhuch  der  Physiologie  des  Menschen" 
has  already  passed  through  Four  large  Editions  since  its  first  appearance 
in  1880,  shows  that  in  some  special  way  it  has  met  the  wants  of 
Students  and  Practitioners  in  Germany.  The  characteristic  which 
has  thus  commended  the  work  will  be  found  mainly  to  lie  in  its 
eminent  pracUadity ;  and  it  is  this  consideration  which  has  induced 
me  to  undertake  the  task  of  putting  it  into  an  English  dress  for 
English  readers. 

Landois'  work,  in  fact,  forms  a  Bridge  between  Physiology  and  the 
Practice  of  Medicine.  It  never  loses  sight  of  the  fact  that  the  Student 
of  to-day  is  the  practising  Physician  of  to-morrow.  Thus,  to  every 
Section  is  appended — after  a  full  description  of  the  normal  processes — 
a  short  rSsumd  of  the  pathological  variations,  the  object  of  this  being  to 
direct  the  attention  of  the  Student,  from  the  outset,  to  the  field  of  his 
future  practice,  and  to  show  him  to  what  extent  pathological  processes 
are  a  disturbance  of  the  normal  activities. 

In  the  same  way,  the  work  off'ers  to  the  busy  physician  in  practice  a 
ready  means  of  refreshing  his  memory  on  the  theoretical  aspects  of 
Medicine.  He  can  pass  bacJcwards  from  the  examination  of  pathological 
phenomena  to  the  normal  processes,  and,  in  the  study  of  these,  find  new 
indications  and  new  lights  for  the  appreciation  and  treatment  of  the 
cases  under  consideration. 

With  this  object  in  view,  all  the  methods  of  investigation  which  may 
with  advantage  be  used  by  the  Practitioner,  are  carefully  and  fully 
described ;  and  Histology,  also,  occupies  a  larger  place  than  is  usually 
assigned  to  it  in  Text-books  of  Physiology. 

A  word  as  to  my  own  share  in  the  present  version : — 

(1.)  In  the  task  of  translating,  I  have  endeavoured  throughout  to 
convey  the  author's  meaning  accurately,  without  a  too  rigid  adherence 
to  the  original.  Those  who  from  experience  know  something  of  the 
difficulties  of  such  an  undertaking  will  be  most  ready  to  pardon  any 
shortcomings  they  may  detect. 


viii  PREFACE. 

(2.)  Very  considerable  additions  have  been  made  to  the  Histological, 
and  also  (where  it  has  seemed  necessary)  to  the  Physiological  sections. 
All  such  additions  are  enclosed  within  square  brackets  [  ].  I  have  to 
acknowledge  my  indebtedness  to  many  valuable  Papers  in  the  various 
]\Iedical  Journals — British  and  Foreign — and  also  to  the  Histological 
Treatises  of  Cadiat,  Ptanvier,  and  Klein;  Quain^s  Anatomy,  vol.  ii., 
ninth  edition;  Hermann's  Randhuch  der  Physiologie;  and  the  Text- 
books on  Physiology,  by  Eutherford,  Foster,  and  Kirkes;  Gamgee's 
Physiological  Chemistry;  Ewald's  Digestion;  and  Koberts's  Digestive 
Ferments. 

(3.)  The  Illustrations  have  been  increased  in  number  from  106 
in  the  Fourth  German  Edition  to  176  in  the  English  version.  These 
additional  Diagrams,  with  the  sources  whence  derived,  are  distinguished 
in  the  List  of  "Woodcuts  by  an  asterisk. 

There  only  remains  for  me  now  to  express  my  thanks  to  all  who 
have  kindly  helped  in  the  progTess  of  the  work,  either  by  furnishing 
Illustrations  or  otherwise  —  especially  to  Drs.  Byrom  Bramwell, 
Dudgeon,  Lauder  Brunton,  and  Knott ;  Mr,  Hawksley;  Professors 
Hamilton  and  M'Kendrick;  to  my  esteemed  teacher  and  friend, 
Professor  Ludwig,  of  Leipzic;  and,  finally,  to  my  friend,  Mr.  A.  W, 
Eobertson,  M.A.,  formerly  Assistant  Librarian  in  the  University,  and 
now  Librarian  of  the  Aberdeen  Public  Library,  for  much  valuable 
assistance  while  the  Avork  was  passing  through  the  press. 

The  Second  Part  will,  it  is  hoped,  be  issued  early  in  1885. 

In  conclusion — and  forgetting  for  the  moment  my  own  connection 
with  it — I  heartily  commend  the  work  j;er  se  to  the  attention  of 
Medical  Men,  and  can  wish  for  it  no  better  fate  than  that  it  may 
speedily  become  as  popular  in  this  country  as  it  is  in  its  Fatherland. 

WILLIAM  STIRLING, 


Aberdeen  University, 
November,  1884, 


GENEEAL    CONTENTS, 


INTRODUCTION. 

PAGB 

The  Scope  of  Physiology,  and  its  Relation  to  the  othei-  Branches  of  Natural 

Science,           ............  xix 

Matter, xx 

Forces, xxii 

Law  of  the  Conservation  of  Energy,      ........  xxvii 

Animals  and  Plants,      ..........  xxviii 

Vital  Energy  and  Life, xxxi 

I.    PHYSIOLOGY   OF   THE    BLOOD. 

SECTION 

1.  Physical  Properties  of  the  Blood, 1 

2.  Microscopic  Examination  of  the  Blood,  .......  3 

3.  Histology  of  the  Human  Red  Blood-Corpuscles, 7 

4.  Effects  of  Reagents  on  the  Blood-Corpuscles, 7 

5.  Preparation  of  the  Stroma — Making  Blood  "  Lake-Coloured,''        .         .  10 

6.  Form  and  Size  of  the  Blood-Corpuscles  of  Different  Animals,          .         .  11 

7.  Origin  of  the  Red  Blood-Corpuscles,       .         .         .         .         .         .         .  12 

8.  Decay  of  the  Red  Blood-Corpuscles,        .......  16 

9.  The  Colourless  Corpuscles — Leucocytes,          .         .         .         .         .         .  17 

10.  Abnormal  Changes  of  the  Blood-Corpuscles,  ......  22 

11.  Chemical  Constituents  of  the  Red  Blood-Corpuscle.s,      ....  23 

12.  Preparation  of  Hjemoglobin  Crystals,      .......  24 

13.  Quantitative  Estimation  of  Hcemoglobin,        ......  25 

14.  Use  of  the  Spectroscope, 27 

15.  Compounds  of  Hismoglobin — Methsemoglobin,        .....  29 

16.  Carbonic  Oxide-Hfemoglobin, 31 

17.  Poisouuig  by  Carbonic  Oxide,          ........  32 

18.  Decomposition  of  Hsemoglobin,       ........  33 

19.  Hsemin  and  Blood  Tests, 34 

20.  Hffimatoidin,            ...........  35 

21.  The  Colourless  Proteid  of  Haemoglobin, 36 

22.  Proteids  of  the  Stroma, 36 

23.  The  other  Constituents  of  Red  Blood-Corpuscles,             ....  36 

24.  Chemical  Composition  of  the  Colourless  Corpuscles,        ....  37 

25.  Blood-Plasma,  and  its  Relation  to  Serum,       ......  37 

26.  Preparation  of  Plasma,            .........  38 

27.  Fibrin — Coagulation  of  the  Blood, 39 

28.  General  Phenomena  of  Coagulation, 40 

29.  Cause  of  the  Coagulation  of  the  Blood, 43 

30.  Source  of  the  Fibrin- li'actors, 46 

31.  Relation  of  the  Red  Blood-Corpuscles  to  the  Formation  of  Fibrin,         .  47 


S:  CONTENTS. 

SECTION  PASB 

32.  Chemical  Composition  of  the  Plasma  and  Serum,            ....  49 

33.  The  Gases  of  the  Blood, 51 

34.  Extraction  of  the  Blood  Gases, 53 

35.  Quantitative  Estimation  of  the  Blood  Gases, 55 

36.  The  Blood  Gases,     ...........  55 

37.  Is  ozone  (O3)  present  m  Blood  ?       .         .......  57 

38.  Carbonic  Acid  and  Nitrogen  in  Blood,     .......  58 

39.  Arterial  and  Venous  Blood, 59 

40.  Quantity  of  Blood, 60 

41.  Variations  from  the  Normal  Conditions  of  the  Blood,     ....  61 

II.   PHYSIOLOGY  OF   THE   CIRCULATION. 


42.  General  View  of  the  Circulation,     . 

43.  The  Heart, 

44.  Arrangement  of  the  Cardiac  Muscular  Fibres, 

45.  Arrangement  of  the  Ventricular  Fibres, 

46.  Pericardium,  Endocardium,  Valves, 

47.  Self-Steering  Action  of  the  Heart, 

48.  The  Movements  of  the  Heart,        .        .         . 

49.  Pathological  Disturbances  of  Cardiac  Action, 

50.  The  Apex -Beat— the  Cardiogram, 

51.  The  Time  occupied  by  the  Cardiac  Movements, 

52.  Pathological  Disturbance  of  the  Cardiac  Impulse, 

53.  The  Heart-Sounds,  .... 

54.  Variations  of  the  Heart-Sounds,     . 

55.  The  Duration  of  the  Movements  of  the  Heart 

56.  Innervation  of  the  Heart, 

57.  The  Cardiac  Nerves,        .... 

58.  The  Automatic  Motor-Centres  of  the  Heart, 

59.  The  Cardio-Pneumatic  Movements, 

60.  Influence  of  the  Respiratory  Pressure  on  the  Heart 


65 
66 
67 
69 
71 
73 
76 
79 
80 
85 
89 
91 
95 
96 
97 
97 
98 
109 
111 


THE  CIRCULATION. 


61.  The  Flow  of  Fluids  through  Tubes, 

62.  Propelling  Force,  Velocity  of  Current,  Lateral  Pressure, 

63.  Currents  through  Capillary  Tubes, 

64.  Movements  of  Fluids  and  Wave-Motion  in  Elastic  Tubes, 

65.  Structure  and  Properties  of  the  Blood-Vessels,       , 

66.  The  Pulse — Historical,  

67.  Instruments  for  Investigating  the  Pulse,        .... 

68.  The  Pulse-Curve  or  Sphygmogram, 

69.  Dicrotic  Pulse, 

70.  Characters  of  the  Pulse, 

71.  Variations  in  the  Strength,  Tension,  and  VolTime  of  the  Pulse, 

72.  The  Pulse-Curves  of  various  Arteries, 

73.  Anacrotism, 

74.  Influence  of  the  Respiratory  Movements  on  the  Pulse-Curve, 

75.  Influence  of  Pressure  upon  the  Form  of  the  Pulse-Wave, 

76.  Rapidity  of  Transmission  of  Pulse- Waves 

77.  Propagation  of  the  Pulse-Wave  in  Elastic  Tubes,    . 

78.  Velocity  of  the  Pulse-Wave  in  Man,       ..... 


115 
115 
118 
118 
119 
127 
128 
136 
140 
141 
143 
144 
146 
148 
151 
152 
152 
154 


CONTENTS.  XI 

Section  page 

79.  Further  Pulsatile  Phenomena, ,  156 

80.  Vibrations  Communicated  to  the  Body  by  the  Action  of  the  Heart,      •  157 

81.  The  Blood-Current, 159 

82.  Schemata  of  the  Circulation, 161 

83.  Capacity  of  the  Ventricles, 161 

84.  Estimation  of  the  Blood-Pressure, 162 

85.  Blood-Pressure  in  the  Artei'ies,     ........  166 

86.  Blood-Pressure  in  the  Capillaries, 173 

87.  Blood-Pressure  in  the  Veins,          ........  175 

88.  Blood-Pressure  in  the  Pulmonary  Artery,     .         .         .         .         .         .177 

89.  Measurement  of  the  Velocity  of  the  Blood- Stream,        ....  179 

90.  Velocity  of  the  Blood  in  Arteries,  Capillaries,  and  Veins,     .         .         .  182 

91.  Estimation  of  the  Capacity  of  the  Ventricles, 184 

92.  The  Duration  of  the  Circulation,   . 184 

93.  Work  of  the  Heart, 185 

94.  Blood- Cui-rent  m  the  Smallest  Vessels, 186 

95.  Passage  of  the  Blood-Corpuscles  out  of  the  Vessels — [Diapedesis],          .  189 

96.  Movement  of  the  Blood  in  the  Veins, 190 

97.  Sounds  or  Bruits  within  Arteries, 192 

98.  Venous  Murmurs, 193 

99.  The  Venous  Pulse — Phlebogram,  .         .         .         .         .         .         .         .194 

100.  Distribiition  of  the  Blood, 196 

101.  Plethysmography, 197 

102.  Transfusion  of  Blood, 199 

THE  BLOOD-GLANDS. 

103.  The  Spleen— Thymus — Thyroid— Supra-Eenal  Capsules— Hypophysis 

Cerebri— Coccygeal  and  Carotid  Glands, 203 

104.  Comparative, 215 

105.  Historical  Retrospect, 215 

III.  PHYSIOLOGY  OF  RESPIRATION. 


106.  Structure  of  the  Air-Passages  and  Lungs,     , 

107.  Mechanism  of  Respiration, 

108.  Quantity  of  Gases  Respired,  .... 

109.  Number 'of  Respirations,       ..... 

110.  Time  occupied  by  the  Respiratory  Movements, 

111.  Pathological  Variations  of  the  Respiratory  Movements, 

112.  General  View  of  the  Respiratory  Muscles,    . 

113.  Action  of  the  Individual  Pv,espiratory  Muscles, 

114.  Relative  Size  of  the  Chest, 

115.  Pathological  Variations  of  the  Percussion  Sounds, 

116.  The  Normal  Respiratory  Sounds, 

117.  Pathological  Respiratory  Sounds, 

118.  Pressure  in  the  Air- Passages  during  Respiration, 

119.  Appendix  to  Respiration,      ..... 

120.  Peculiarly  Modified  Respiratory  Sounds, 

121.  Quantitative  Estimation  of  CO2,  O,  and  Watery  Vapour, 

122.  Methods  of  Investigation, 

123.  Composition  and  Properties  of  Atmospheric  Air,  . 


217 
226 
227 
229 
229 
233 
234 
235 
240 
244 
245 
245 
247 
248 
248 
250 
250 
254 


xii  CONTENTS. 

SECTION  P'^^^ 

124.  Composition  of  Expired  Air, 254 

125.  Daily  Quantity  of  Gases  Exchanged, 256 

126.  Review  of  the  Daily  Gaseous  Income  and  Expenditure,         .         ,         .  256 

127.  Conditions  Influencing  the  Gaseous  Exchanges, 256 

128.  Diffusion  of  Gases  within  the  Lungs, 259 

129.  Exchange  of  Gases  between  the  Blood  and  the  Air,       ....  260 

130.  Dissociation  of  Gases, 263 

131.  Cutaneous  Respiration, 264 

132.  Internal  Respiration, 265 

133.  Respiration  in  a  Closed  Space, .         .  267 

134.  Dyspncea  and  Asphyxia, 268 

135.  Respiration  of  Foreign  Gases,        ........  271 

136.  Accidental  Impurities  of  the  Air, '  272 

137.  Ventilation  of  Rooms, 272 

138.  Formation  of  Mucus, 273 

139.  Action  of  the  Atmospheric  Pressure, 275 

140.  Comparative  and  Historical, 277 

IV.  PHYSIOLOGY  OF  DIGESTION. 

141.  The  Mouth  and  its  Glands, 279 

142.  The  Salivary  Glands, ' .         •        .         .280 

143.  Histological  Changes  in  the  Salivary  Glands, 283 

144.  The  Nerves  of  the  Salivary  Glands, 285 

145.  Action  of  Nerves  on  the  Salivarj;-  Secretion, 286 

146.  The  Saliva  of  the  Individual  Glands, 291 

147.  The  Mixed  Saliva  in  the  Mouth, 292 

148.  Physiological  Action  of  Saliva, 294 

149.  Tests  for  Sugar, 297 

150.  Quantitative  Estimation  of  Sugar, 298 

151.  Mechanism  of  the  Digestive  Apparatus,         .         .         .         .         .         .  298 

152.  Introduction  of  the  Food, 298 

153.  The  Movements  of  Mastication, 299 

154.  Structure  and  Development  of  the  Teeth,      .         .         .         .         .        .  300 

155.  Movements  of  the  Tongue, •        .  304 

156.  Deglutition, 305 

157.  Movements  of  the  Stomach, 309 

158.  Vomiting, 310 

159.  Movements  of  the  Intestine, 312 

160.  Excretion  of  Faecal  Matter, 313 

161.  Influence  of  Nerves  on  the  Intestine,    ....;••  316 

162.  Structure  of  the  Stomach, 321 

163.  The  Gastric  Juice, 325 

164.  Secretion  of  Gastric  Juice,     . 326 

165.  Methods  of  obtaining  Gastric  Juice,      .......  330 

166.  Process  of  Gastric  Digestion, 331 

167.  Gases  in  the  Stomach, 336 

168.  Structure  of  the  Pancreas, 337 

169.  The  Pancreatic  Juice, 339 

170.  Digestive  Action  of  the  Pancreatic  Juice, 340 

171.  The  Secretion  of  the  Pancreatic  Juice, 340 

172.  Preparation  of  Peptonised  Food, 345 


CONTENTS.  3dii 

SECtlON  PAGE 

173.  Structure  of  the  Liver, .346 

174.  Chemical  Composition  of  the  Liver-Cells, 350 

Diabetes  Mellitus,  or  Glycosuria,          .......  352 

The  Functions  of  the  Liver, 354 

Constiti;ents  of  the  Bile,         .........  354 

Secretion  of  Bile, .  359 

Excretion  of  Bile,           - 361 

180.  Reabsorption  of  Bile, 362 

181.  Functions  of  the  Bile, 365 

Fate  of  the  Bile  in  the  Intestine,  ........  367 

The  Intestinal  Juice,     ..........  368 

Fermentation  Processes  in  the  Intestine,       .         .         .         .         .         .371 

Processes  in  the  Large  Intestine,  ........  377 

186.  Pathological  Variations,        .........  380 

187.  Comparative  Physiology, 383 

188.  Historical  Retrospect, 384 


175. 
176. 
177. 

178. 
179. 


182. 
183. 
184. 
185. 


V.   PHYSIOLOGY  OF  ABSORPTION. 

189.  The  Organs  of  Absorption,   ,        . 386 

190.  Structure  of  the  Small  and  Large  Intestines,         .....  386 

191.  Absorption  of  the  Digested  Food, 392 

192.  Absorptive  Activity  of  the  Wall  of  the  Intestme,          ....  395 

193.  Influence  of  the  Nervous  System, 400 

194.  Feeding  with  "Nutrient  Enemata," 40O 

195.  Chyle-Vessels  and  Lymphatics,     ........  401 

196.  Origin  of  the  Lymphatics,     .........  402 

197.  The  Lymiih-Glands 406 

198.  Properties  of  Chyle  and  Lymph,   ........  409 

199.  Quantity  of  Lymph  and  Chyle, 412 

200.  Origin  of  Lymph, 413 

201.  Movement  of  Chyle  and  Lymph,  ........  415 

202.  Absorption  of  Parenchymatous  Effusions,     ......  418 

203.  Congestion  of  Lymph,  Serous  Effusions  and  Qildenia,     .         .         .         .419 

204.  Comparative  Physiology,       .         .         , 420 

205.  Historical  Retrospect, 421 


VI.  PHYSIOLOGY  OF  ANIMAL  HEAT 


206.  Sources  of  Heat, 

207.  Homoiothermal  and  Poikilothermal  Animals, 

208.  Methods  of  Estimating  Temperature — Thermometry, 

209.  Temperature— Topograi)liy,  .... 

210.  Conditions  Influencing  the  Temperature  of  Organs, 

211.  Estimation  of  the  Amount  of  Heat — Caloiimetry, 

212.  Thermal  Conductivity  of  Animal  Tissues,     . 

213.  Variations  of  the  Mean  Temperature,    . 

214.  Regulation  of  the  Temperature,     .... 

215.  Income  and  Expenditure  of  Heat,  .         .         . 

216.  Variations  in  Heat  Production,     .... 

217.  Relation  of  Heat  Production  to  Bodily  Work, 

218.  Accommodation  for  Different  Temperatures, 


422 
426 
427 
4.S0 
432 
434 
436 
437 
441 
445 
447 
447 
448 


XiV  CONTENTS. 

SECIION  PAGE 

219.  storage  of  Heat  in  the  Body, 450 

220.  Fever, 450 

221.  Artificial  Increase  of  the  Temperature, 452 

222.  Employment  of  Heat, .453 

223.  Increase  of  Temperature  post  mortem,  .......  453 

224.  Action  of  Cold  on  the  Body, 454 

225.  Artificial  Lowering  of  Temperature,      .         .         .         .         .         .      ,  .  455 

226.  Employment  of  Cold, 456 

227.  Heat  of  Inflamed  Parts, 457 

228.  Historical  and  Comparative,         • 457 

VII.  PHYSIOLOGY  OF  THE  METABOLIC  PHENOMENA 
OF  THE  BODY. 


229.  General  View  of  Food-Stuffs, 

230.  Structure  and  Secretion  of  the  Mammary  Glands 

231.  Milk  and  its  Preparations,   .... 

232.  Eggs,    .        .        ... 

233.  Flesh  and  its  Preparations,   .... 

234.  Vegetable  Foods, 

235.  Condiments— Tea  and  Alcohol,     . 


458 
461 
464 
468 
469 
471 
473 


PHENOMENA  AND  LAWS  OF  METABOLISM. 

236.  Equilibrium  of  the  Metabolism,    . 

237.  Metabolism  during  Hunger  and  Starvation, 

238.  Metabolism  during  a  purely  Flesh  Diet, 

239.  A  Diet  of  Fat  or  of  Carbohydrates, 

240.  Mixture  of  Flesh  and  Fat,     . 

241.  Origin  of  Fat  in  the  Body,    . 

242.  Corpulence,  .... 

243.  The  Metabolism  of  the  Tissues, 

244.  Eegeneration  of  the  Tissues, 

245.  Transplantation  of  the  Tissues, 

246.  Increase  in  Size  and  Weight  during  Growth, 


476 

482 
485 
486 
486 
487 
488 
490 
493 
497 
497 


GENERAL  VIEW  OF  THE  CHEMICAL  CONSTITUENTS  OF 
THE  ORGANISM. 

247.  Inorganic  Constituents, 499 

248.  Organic  Constituents — Proteids, 500 

249.  The  Animal  and  Vegetable  Proteids  and  their  Properties,     .        .         .  502 

250.  The  Albuminoids,  .         .         , '      .  504 

251.  The  Fats, 508 

252.  The  Carbohydrates,       .         .         .         .' 511 

253.  Historical  Pv,etrospect, 514 


LIST    OF    ILLUSTEATIONS. 


FIGURE  PAGE 

1.  Human  coloured  blood-corpuscles,  .            ,            #            #            .  3 

2.  Malassez's  apparatus  for  estimating  the  number  of  blood-corpuscles,   .  4 
*3.  Gower's  hagmacytometer  (Hawksley),     .....  6 

4.  Eed  blood-corpuscles  showing  various  changes  of  shape,  .            .  9 

5.  Vaso-formative  cells,       .  .            .             .            .             .             .  14 

6.  White  blood-corpuscles,  ......  18 

7.  Blood-plates  and  their  derivatives,         .....  21 

8.  Hjemoglobin  crystals,     .....,•  24 
*9.  Gower's  hfemoglobinometer  (Hawksley),           ....  26 

10.  Scheme  of  a  spectroscope,  ......  28 

11.  Various  spectra  of  htemoglobin,  .....  29 

12.  Hjemin  crystals,  ........  34 

13.  Hasmm  crystals  prepared  from  traces  of  blood,  ...  34 

14.  Hfematoidin  crystals,      .......  35 

15.  Scheme  of  Pfluger's  gas-pump,    ......  53 

16.  Scheme  of  the  circulation,  ......  65 

17.  Muscular  fibres  from  the  heart,  .....  66 

18.  Muscular  fibres  in  the  left  auricle,  .....  68 

19.  Muscular  fibres  in  the  ventricles,  •  •  .  .  .  70 
*20.  Lymphatic  from  the  pericardium  (Cadiaf*,  .  .  .  .71 
*21.  Section  of  the  endocardium  (Cadiat),  .....  71 
*22,  Purkinje's  fibres  (Ranvier),         ......  73 

23.  Cast  of  the  ventricles  of  the  human  heart,         ....  77 

24.  The  closed  semilunar  valves,       ......  78 

*25.  Various  cardiographs  (Hermann),           .....  81 

25a.  Curves  of  the  apex-beat,  .            ,            .            .            .             .82 

26.  Changes  of  the  heart  during  systole,      .....  83 

27.  Curves  from  a  rabbit's  ventricle,  .....  86 
*28.  Marey's  registering  tambour  (Hermann),           ....  87 

29.  Curves  obtained  with  a  cardiac  sound,  ....  88 

30.  Curves  from  the  cardiac  impulse,  .....  90 

31.  Position  of  the  heart  in  the  chest  (Luschka  and  Gairdner),       .  ,  93 
31a.  Bipolar  nerve-cells  from  a  frog's  heart,  .            .             ,             .98 

*32.  Scheme  of  a  frog-manometer  (Stirling),  .....  102 

*32a.  Perfusion  cannula  (Kronecker  and  Stirling),    .  .            .             ,102 

*33.  Roy's  tonometer  (Stirling),          ......  103 

*34,  Luciani's  groups  of  cardiac  pulsations  (Hermann),         .            .             ,  104 

*35.  Curves  of  a  frog's  heart  at  diff'erent  temperatures  (Hermann),  .            ,  105 

36.  Cardio-pneumograph  of  Landois,    ...,,,  HO 


XVI 


ILLUSTRATIONS. 


37.  Apparatus  for  showiug  the  effect  of  respiration, 

38.  Cylindrical  vessel,  .... 

39.  Cylindrical  vessel  with  manometers,      .  . 

40.  Small  artery  with  its  various  coats, 

41.  Capillaries  injected  with  silver  nitrate, 
*42.  Longitudinal  section  of  a  vein  at  a  valve  (Cadiat), 

43.  Poiseuille's  pulse-measurer, 

44.  Sphygmometer  of  Herisson, 

45.  Scheme  of  Marey's  sphygmograph, 
*46.  Marey's  improved  sphygmograph  (B.  Bramwell), 
*47.  Scheme  of  Marey's  sphygmograph  in  working  order  (B.  Bramwell), 
*48.  Scheme  of  Marey's  sphygmograph  after  increase  of  the  pressure  (B 

Bramwell),     ...... 

*49.  Dudgeon's  sphygmograph  (Dudgeon),     . 

*50.  Mode  of  applying  Dudgeon's  si)hygmograph  (Dudgeon), 

*51.  Sphygmogram  (Dudgeon),  .... 

52.  Scheme  of  Brondgeest's  pansphygmograi^h, 

53.  Scheme  of  Landois'  angiograph, 

54.  Pulse-curves  of  the  carotid,  radial,  and  posterior  tibial  arteries 

55.  Landois'  gas-sphygmoscope,        , 

56.  Hsemautographic  curve,  .... 
*57.  Sphygmogram  of  radial  artery  (Dudgeon), 

58.  Sphygmograms  of  various  arteries, 

59.  Pulsus  dicrotus,  P.  caprizans,  P.  monocrotus,   . 

60.  Pulsus  alter  nans,  .... 

61.  Curves  of  the  posterior  tibial  and  pedal  arteries, 

62.  Anacrotic  pulse-curves,  .... 

63.  Influence  of  the  respiration  on  the  sphygmogram, 

64.  Curves  of  the  radial  and  carotid  arteries  during  MuUer's  and  Val 

salva's  experiments, 

65.  Pulsus  paradoxus,  .  '.         '   . 

66.  Various  radial  curves  altered  by  pressure, 

67.  Apparatus  for  measuring  the  velocity  of  the  pulse-wave  in  an  elastic 

tube,  ...... 

67a.  Tracing  obtained  from  67,         .  .  , 

68.  Pulse  tracings  of  the  radial  and  carotid  arteries, 

69.  Tracings  from  the  posterior,  tibial,  and  carotid  arteries, 

70.  Apparatus  for  registering  the  molar  motions  of  the  body, 

71.  Vibration  and  heart  curves,        .... 

72.  Ludwig  and  Fick's  kymographs, 
*73.  Ludwig's  improved  revolving  cylinder  (Hermann), 
*74.  Blood-pressure  tracing  of  the  carotid  of  a  dog  (Hermann), 
*75.  Fick's  spring  kymogi-aph  by  Hering  (Hermann), 
*76.  Depressor  curve  (Stirling),  .... 

77.  Blood-pressure  and  respiration  tracings  taken  simultaneously, 
*78.  Blood-pressure  tracing  during  stimulation  of  the  vagus  (Stirling), 
*79.  f  Apparatus  of  v,  Kries  for  estimating  the   capillary   pressure   (C 

80.1  Ludwig), 

81.  Volkmann's  hsemadromometer, 

82.  Ludwig  and  Dogiel's  rheometer, 

83.  Vierordt's  hsematachometer, 

84.  Dromograph,       .... 


PAGB 

113 
115 
116 
120 
122 
123 
128 
128 
129 
130 
130 

130 
131 
131 
132 
132 
133 
134 
135 
1.36 
137 
138 
140 
143 
145 
147 
148 

150 
150 
151 

153 
154 
155 
156 
157 
158 
163 
164 
165 
166 
168 
169 
173 

174 

180 
180 
181 
182 


riGTOB 

85. 
86. 
87. 

*88. 

*89. 

*90. 

*91. 

*92. 

*93. 

*94. 

*95. 

*97. 

*98. 

99. 

*100. 

101. 

102. 

103. 

104. 

105. 

106. 

107. 

108. 

109. 

110. 

111. 

112. 

113. 

114. 

115. 

116. 
*117. 
*118. 
*119. 
*120. 

121. 

122. 

123. 

124. 

125. 

126. 

127. 

128. 

129. 

130. 
*131. 
*132. 

133. 

134. 

135. 

136. 

*137. 


ILLUSTRATIONS. 

Diapedesis,        ...  .        ' 

Various  forms  of  venous  pulse, 

Mosso's  plethysmograph, 

Trabecule  of  the  spleen  (Cadiat), 

Adenoid  tissue  of  spleen  (Cadiat), 

Malpighian  corpuscle  of  the  spleen  (Cadiat), 

Tracing  of  a  splenic  curve  (Roy), 

Thymus  gland  (Cadiat),  . 

Elements  of  the  thymus  gland  (Cadiat), 

Thyroid  gland  (Cadiat), 

Supra-renal  capsule  (Cadiat),    . 

Human  bronchus  (Hamilton),  . 

Air-vesicles  injected  with  silver  nitrate  (Hamilton), 

Scheme  of  the  air-vesicles  of  lung. 

Interlobular  septa  of  lung  (Hamilton), 

Scheme  of  Hutchinson's  spirometer,'     . 

Marey's  stethograph  (M'Kendrick),     . 

Brondgeest's  tambour  and  curve, 

Pneumatogram,  ,  , 

Section  through  diaphragm  (Hermann), 

Action  of  intercostal  muscles,     . 

Cyrtometer  curve, 

Sibson's  thoracometer,  . 

Topography  of  the  lungs  and  heart, 

Andral  and  Gavarret's  respiration  apparatus, 

Scharling's  apparatus,  . 

Regnault  and  Reiset's  apparatus, 

V.  Pettenkofer's  apparatus, 

Valentin  and  Brunner's  apparatus, 

Objects  found  in  sputum, 

Histology  of  the  salivary  glands. 

Human  sub-maxillary  gland  (Heidenhain), 

I    Sections  of  a  serous  gland  (Heidenhain), 

Diagram  of  a  salivary  gland  (L.  Brunton), 

Apparatus  for  estimation  of  sugar, 

Vertical  section  of  a  tooth. 

Dentine, 

Dentine  and  enamel, 

Dentine  and  crusta  petrosa, 

>  Development  of  a  tooth, 

Perinseum  and  its  muscles. 

Levator  ani  externus  and  intemus, 

Auerbach's  plexus  (Cadiat), 

Meissner's  plexus  (Cadiat), 

Surface  section  of  gastric  mucous  membrane, 

Fundus  gland  of  the  stomach,  . 

Pyloric  gland  and  goblet- cells, . 

Scheme  of  the  gastric  mucous  membrane, 

Pyloric  mucous  membrane  (Hermann), 


XVll 

PAGE 
190 

195 
198 
203 
203 
205 
209 
212 
212 
213 
214 
219 
221 
222 
223 
228 
230 
230 
231 
236 
237 
241 
242 
243 
251 
251 
252 
253 
255 
274 
281 
282 

284 

289 
298 
300 
300 
301 
302 


302  and  303 


314 
315 
317 
317 
321 
322 
323 
324 
326 


xvm  ILLUSTRATIONS. 

riGUEB 

*138.  Pyloric  glands  during  digestion  (Hermann),     . 
*139.  Section  of  the  tubes  of  the  pancreas  (Hermann), 

140.  Changes  of  the  pancreatic  cells  during  activity, 

141.  Scheme  of  a  liver  lobule, 
*142.  Human  liver-cells  (Cadiat), 
*143.  Liver-cells  during  fasting  (Hermann), . 

144.   Various  appearances  of  the  liver-cells, 
*145.  Cholesterin  (Aitken),     . 
*146.  Lieberkiihn's  gland  (Hermann), 

147.  Bacterium  aceti  and  B.  butyricus, 

148.  Bacillus  subtilis, 
*149.  Villi  of  small  intestine  injected  (Cadiat), 

150.  Scheme  of  an  intestinal  villus, 
*151.  Villi  and  Lieberkiihn's  follicles  (Cadiat), 
*152.  Section  of  a  solitary  follicle  (Cadiat),  . 
*153.  Section  of  a  Peyer's  patch  (Cadiat), 
*154.  Section  of  Auerbach's  plexus  (Cadiat), 
*155.  Lieberkiihn's  gland  (Hermann), 

156.  Endosmometer, 

157.  Origin  of  lymphatics  in  the  tendon  of  diaphragm, 
*158.  Lymphatics  of  diaphragm  silvered  (Ranvier), 

159.  Perivascular  lymphatics, 

160.  Stomata  from  lymph-sac  of  frog, 

161.  Section  of  two  lymph-follicles, 
*162.  Scheme  of  a  lymphatic  gland  (Knott), 

163.  Part  of  a  lymphatic  gland         , 
*164.  Section  of  central  tendon  of  diaphragm  (Brunton), 
*165.  Section  of  fascia  lata  of  a  dog  (Brunton),         , 

166.  Water  calorimeter  of  Favre  and  Silbermann,  . 

167.  "Walferdin's  metastatic  thermometer,  . 

168.  Scheme  of  thermo-electric  arrangements, 

169.  Kopp's  apparatus  for  specific  heat, 

170.  Daily  variations  of  temperature, 

*17l.  Aciui  of  the  mammary  gland  of  a  sheep  (Cadiat), 
172.  Milk-glands  during  inaction  and  secretion, 
*173.  Section  of  a  grain  of  wheat  (Blyth), 

174.  Yeast-cells  grovtdng,      .... 

175.  Composition  of  animal  and  vegetable  foods, 

176.  Starch  grains  (Blyth),   .... 


PAGE 

326 
337 
338 
347 
348 
348 
349 
358 
369 
373 
375 
387 
388 
389 
390 
391 
391 
392 
393 
403 
403 
405 
405 
406 
407 
408 
416 
416 
422 
427 
428 
435 
439 
462 
462 
471 
474 
479 
512 


[The  illustrations  indicated  by  the  word  Hermann,  are  from  Hermann's 
Eandhuch  der  Physiologie;  by  Cadiat,  from  Cadiat's  Trait4  d'Anatomie  06n6rale; 
by  Pian-vder,  from  Pvanvier's  TraitA  Technique  d" Histologie ;  by  Brunton,  from  The 
Practitioner:  and  by  Hamilton,  from  Hamilton's  Pathology  of  Bronchitis.1 


Introduction. 


The  Scope  of  Physiology  and  its  Relations  to  other 
Branches  of  Natural  Science, 

Physiology  is  the  science  of  the  vital  phenomena  of  organisms,  or 
broadly,  it  is  the  Doctrine  of  Life.  Correspondingly  to  the  divisions 
of  organisms,  we  distinguish — (1)  Animal  Physiology;  (2)  Vegetable 
Physiology;  and  (3)  the  Physiology  of  the  Lowest  Living  Organisms,  which 
stand  on  the  border  line  of  animals  and  plants — ie.,  the  so-called 
Protistce  of  Hseckel,  micro-organisms,  and  those  elementary  organisms 
or  cells  which  exist  on  the  same  level. 

The  object  of  Physiology  is  to  estabHsh  these  phenomena,  to  deter- 
mine their  regularity  and  causes,  and  to  refer  them  to  the  general 
fundamental  laws  of  Natural  Science,  viz.,  the  Laws  of  Physics  and  of 
Chemistry. 

The  following  Scheme  shows  the  relation  of  Physiology  to  the 
allied  branches  of  Natural  Science  : — 


Biology. 

The  science   of   organised    beings   or   organisms    (animals,   plants, 
protistse,  and  elementary  organisms). 


I.  Morphology. 

The    doctrine    of   the  form   of 
organisms. 


General 
Morphology. 

The  doctrine  of  the 
formed  elemen- 
tary constituents 
of  organisms. 

(Histology)— 
(a)  Histology    of 

Plants, 
(6)  Histology    of 

Animals. 


Special 
Morphology. 

The  doctrine  of 
the  parts  and 
organs  of  organ- 
isms. 

(Organology 
Anatomy)— 
(a)  Phytotomy, 
(6)  Zootomy. 


II.  Physiology- 

The  doctrine  of  the  vital  pheno- 
mena of  organisms. 


General 
Physiology. 
The     doctrine    of 
vital  phenomena 
in  general — 
(a)  Of  Plants, 
(6)  Of  Animals. 


Special 
Physiology. 

The    doctrine     of 
the  activities  of 
the      individual 
organs — 
(a)  Of  Plants, 
(6)  Of  Animals. 


XX 


INTRODUCTION. 


III.  Embrydlogy. 

The  doctrine  of  the  generation  and  development  of  organisms. 

'  1.  History  of  the  develop- 
ment of  single  beings, 
of  the  individual  {e.g., 
of  man)  from  the  ovum 

onwards  (Ontogeny) : 

{a)  In  Plants, 
(6)  In  Animals. 

(  2.  History  of  the  develop- 
ment of  a  whole  stock 
of  organisms  from  the 
lowest  forms  of  the 
series  upwards  (Phy- 

logeny)— 

(a)  In  Plants, 

(b)  In  Animals. 


Morphological  part  of  the 
doctrine  of  develop- 
ment, i.e.,  the  doctrine 
of  form  in  its  stages  of 
development — 

(«)  Genera], 

(&)  Special. 


Physiological  part  of  the 
doctrine     of    develop- 
ment, i.e.,  the  doctrine 
\      of   the  activity  during 
development — 
{a)  General, 
(6)  Special. 


Morphology  and  Physiology  are  of  equal  rank  in  biological  science, 
and  a  previous  acquaintance  with  Morphology  is  assumed  as  a  basis 
for  the  comprehension  of  Physiology,  since  the  work  of  an  organ 
can  only  be  properly  understood  when  its  external  form  and  its 
internal  arrangements  are  known.  Development  occupies  a  middle 
place  between  Morphology  and  Physiology;  it  is  a  morphological 
discipline  in  so  far  as  it  is  concerned  with  the  description  of  the  parts 
of  the  developing  organism ;  it  is  a  physiological  doctrine  in  so  far 
as  it  studies  the  activities  and  vital  phenomena  during  the  course  of 
development. 

Matter. 

The  entire  visible  world,  including  all  organisms,  consists  of 
matter,  i.e.,  of  substance  which  occupies  space. 

We  distinguish  ponderable  matter  which  has  weight,  and  imponderable 
matter  which  cannot  be  weighed  in  a  balance.  The  latter  is  generally 
termed  ether. 

In  ponderable  materials,  again,  we  distinguish  their /or«z,  i.e.,  the 
nature  of  their  limiting  surfaces;  further,  their  volume,  i.e.,  the 
amount  of  space  which  they  occupy;  and  lastly,  their  aggregate  condition, 
i.e.,  whether  they  are  solid,  fluid,  or  gaseous  bodies. 

Ether. — The  ether  fills  the  space  of  the  universe,  certainly  as  far 
as  the  most  distant  visible  stars.  This  ether,  notwithstanding  its 
imponderability,  possesses  distinct  mechanical  properties ;  it  is  infinitely 
more  attenuated  than  any  known  kind  of  gas,  and  behaves  more  like 


INTRODUCTION.  XXI 

a  solid  body  than  a  gas,  resembling  a  gelatinous  mass  rather  than  the 
air.  It  participates  in  the  luminous  phenomena  due  to  the  vibrations 
of  the  atoms  of  the  fixed  stars,  and  hence  it  is  the  transmitter  of 
light,  which  is  conducted  by  means  of  its  vibrations,  with  inconceivable 
rapidity  (42,220  geographical  miles  per  sec.)  to  our  visual  organs 
(Tyndall). 

Imponderable  matter  (ether)  and  ponderable  matter  are  not 
separated  sharply  from  each  other;  rather  does  the  ether  penetrate 
into  all  the  spaces  existing  between  the  smallest  particles  of  ponderable 
matter. 

Particles. — Supposing  that  ponderable  matter  were  to  be  sub- 
divided continuously  into  smaller  and  smaller  portions,  until  we 
reached  the  last  stage  of  division  in  which  it  is  possible  to  recognise 
the  aggregate  condition  of  the  matter  operated  upon,  we  should  call 
the  finely-divided  portions  of  matter  in  this  state  particles.  Particles 
of  iron  would  still  be  recognised  as  solid,  particles  of  water  as  fluid, 
particles  of  oxygen  as  gaseous. 

Molecules. — Supposing,  however,  the  process  of  division  of  the 
particles  to  be  carried  further  still,  we  should  at  last  reach  a  limit 
beyond  which,  neither  by  mechanical  nor  by  physical  means,  could 
any  further  division  be  effected.  "We  should  have  arrived  at  the 
molecules.  A  molecule,  therefore,  is  the  smallest  amount  of  matter 
which  can  still  exist  in  a  free  condition,  and  which  as  a  unit  no 
longer  exhibits  the  aggregate  condition. 

Atoms. — But  even  molecules  are  not  the  final  units  of  matter,  since 
every  molecule  consists  of  a  group  of  smaller  units,  called  atoms.  An 
atom  cannot  exist  by  itself  in  a  free  condition,  but  the  atoms  unite 
with  other  similar  or  dissimilar  atoms  to  form  groups,  which  are 
called  molecules.  Atoms  are  incapable  of  further  sub-division,  hence 
their  name.  We  assume  that  the  atoms  are  invariably  of  the  same 
size,  and  that  they  are  solid.  From  a  chemical  point  of  view,  the 
atom  of  an  elementary  body  (element)  is  the  smallest  amount  of 
the  element  which  can  enter  into  a  chemical  combination.  Just  as 
ponderable  matter  consists  in  its  ultimate  parts  of  ponderable  atoms, 
so  does  the  ether  consist  of  analogous  small  ether-atoms. 

Ponderable  and  Imponderable  Atoms.— The  ponderable  atoms  within 
ponderable  matter  are  arranged  in  a  definite  relation  to  the  ether- 
atoms.  The  ponderable  atoms  mutually  attract  each  other,  and 
similarly,  they  attract  the  imponderable  ether-atoms;  but  the  ether- 
atoms  repel  each  other.  Hence,  in  ponderable  masses,  ether-atoms 
surround  every  ponderable  atom.  These  masses,  in  virtue  of  the 
attraction  of  the  ponderable  atoms,  tend  to  come  together,  but  only 


XXll  INTRODUCTION. 

to  the  extent  permitted  by  the  surrounding  ether-atoms.  Thus,  the 
ponderable  atoms  can  never  come  so  close  as  not  to  leave  interspaces. 
All  matter  must,  therefore,  be  regarded  as  more  or  less  loose  and 
open  in  texture,  a  condition  due  to  the  interpenetrating  ether-atoms, 
which  resist  the  direct  contact  of  the  ponderable  atoms. 

Aggregate  Condition  of  Atoms. — The  relative  arrangement  of  the 
molecules,  ie.,  the  smallest  particles  of  matter,  which  can  be  isolated  in 
a  free  condition,  determines  the  aggregate  condition  of  the  body. 

Within  a  solid  body,  characterised  by  the  permanence  of  its  volume, 
as  well  as  by  the  independence  of  its  form,  the  molecules  are  so 
arranged  that  they  cannot  readily  be  displaced  from  their  relative 
positions. 

Fluid  bodies,  although  their  volume  is  permanent,  readily  change 
their  shape,  and  their  molecules  are  in  a  condition  of  continual 
movement. 

When  this  movement  of  the  molecules  takes  so  wide  a  range  that 
the  individual  molecules  fly  apart,  the  body  becomes  gaseous,  and  as 
such,  is  characterised  by  the  instability  of  its  form  as  well  as  by  the 
changeableness  of  its  volume. 

Physics  is  the  study  of  these  molecules  and  their  motions. 


Forces. 

1.  Gravitation — Work  done. 

All  phenomena  appertain  to  matter.  These  phenomena  are  the 
appreciable  expression  of  the  forces  inherent  in  matter.  The  forces 
themselves  are  not  appreciable,  they  are  the  causes  of  the  phenomena. 

1.  Gravitation. — The  law  of  gravitation  postulates  that  every  particle 
of  ponderable  matter  in  the  universe,  attracts  every  other  particle  with 
a  certain  force.  This  force  is  inversely  as  the  square  of  the  distance. 
Further,  the  attractive  force  is  directly  proportional  to  the  amount  of 
the  attracting  matter,  without  any  reference  to  the  quality  of  the  body. 
We  may  estimate  the  intensity  of  gravitation,  by  the  extent  of  the 
movement  which  it  communicates  to  a  body  allowed  to  fall,  for  one 
second,  through  a  given  distance,  in  a  space  free  from  air.  Such  a  body 
will  fall  in  vacuo  9*809  metres  per  second.  This  fact  has  been  arrived 
at  experimentally. 

Let  us  represent  g  =  9*809  metres,  the  final  velocity  of  the  freely  falling  body  at 
the  end  of  one  second.  The  velocity,  V,  of  the  freely  falling  body  is  proportional 
to  the  time,  t,  so  that 

y  =  gt (1); 


INTRODUCTION.  xxiii 

i.e.,  at  the  end  of  the  Ist  sec,  Y  =  g,  1  =  g  =  9*809  M — the  distance  traversed — 

s  =  !«' (2); 

i.e.,  the  distances  are  as  the  square  of  the  times.     Hence,  from  (1)  and  (2)  it  follows 
(by  eliminating  t)  that — 

V  =  V2^ (3). 

The  velocities  are  as  the  square  roots  of  the  distances  traversed — 

Therefore,  ^ — =  s (4). 

The  freely  falling  body,  and  in  fact  every  freely  moving  body,  possesses 
kinetic  energy,  and  is  in  a  certain  sense  a  magazine  of  energy.  The 
kinetic  energy  of  any  moving  body  is  always  equal  to  the  product  of 
its  weight  (estimated  by  the  balance),  and  the  height  to  which  it 
would  rise  from  the  earth,  if  it  were  thrown  from  the  earth  with  its 
own  velocity. 

Let  W  represent  the  kinetic  energy  of  the  moving  body,  and  P  its  weight,  then 
W  =  P.s,  so  that  from  (4)  it  follows  that — 

W  =  PX      ........     .(5). 

Hence,  the  kinetic  energy  of  a  body  is  proportional  to  the  square  of 
its  velocity. 

"Work. — If  a  force  (pressure,  strain,  tension)  be  so  applied  to  a  body 
as  to  move  it,  a  certain  amount  of  work  is  performed.  The  amount  of 
work  is  equal  to  the  product  of  the  amount  of  the  pressure  or  strain 
which  moves  the  body,  and  of  the  distance  through  which  it  is  moved. 

Let  K  represent  the  force  acting  on  the  body,  and  S  the  distance,  then  the 
work  W  =  K  S.  The  attraction  between  the  earth  and  any  body  raised  above  it 
is  a  source  of  work. 

It  is  usual  to  express  the  value  of  K  in  kilogrammes,  and  S  in 
metres,  so  that  the  "  unit  of  work"  is  the  kilogramme-metre,  i.e.,  the  force 
which  is  required  to  raise  1  kilo,  to  the  height  of  1  metre. 

2.  Potential  Energy. — The  transformation  of  Potential  into  Kinetic 
energy,  and  conversely:  Besides  kinetic  energy,  there  is  also  "potential 
energy,"  or  energy  of  position.  By  this  term  are  meant  various  forms 
of  energy,  which  are  suspended  in  their  action,  and  which,  although 
they  may  cause  motion,  are  not  in  themselves  motion.  A  coiled  watch- 
spring  kept  in  this  position,  a  stone  resting  upon  a  tower,  are  instances 
of  bodies  possessing  potential  energy,  or  the  energy  of  position.  It 
requires  merely  a  push  to  develop  kinetic  from  the  potential  energy, 
or  to  transform  potential  into  kinetic  energy. 


XXIV  INTRODUCTION. 

Work,  w,  was  performed   in   raising   the  stone  to  rest  upon  the 

tower. 

w=p,s,  where  p  ^  the  weight  and  s  =  the  height, 
p  =  m.g,  is  =  the  product  of  the  mass  (m),  and  the  force  of  gravity  (g),  so  that 
w=.mgs. 

This  is  at  the  same  time  the  expression  for  the  potential  energy  of 
the  stone.  This  potential  energy  may  readily  be  transformed  into 
kinetic  energy  by  merely  pushing  the  stone  so  that  it  falls  from  the 
tower.  The  kinetic  energy  of  the  stone  is  equal  to  the  final  velocity 
with  which  it  impinges  upon  the  earth. 

V  =^/  2gs  (see  above  (3). 
V2=      2gs. 
mY^=      2mgs. 


2-^2=       mgs. 


m 


g  s  was  the  expression  for  the  potential  energy  of  the  stone  while 


m . 


it  was  still  resting  on  the  height;  -  Vg  is    the  kinetic   energy    corre- 
sponding to  this  potential  energy  (Briicke). 

Potential  energy  may  be  transformed  into  mechanical  energy  under 
the  most  varied  conditions;  it  may  also  be  transferred  from  one  body 
to  another. 

The  movement  of  a  pendulum  is  a  striking  example  of  the  former.  When  the 
pendulum  is  at  the  highest  point  of  its  excursion,  it  must  be  regarded  as  absolutely 
at  rest  for  an  instant,  and  as  endowed  with  potential  energy,  thus  corresponding 
with  the  raised  stone  in  the  previous  instance.  During  the  swing  of  the  pendulum, 
this  potential  energy  is  changed  into  kinetic  energy,  which  is  greatest  when  the 
pendulum  is  moving  most  rapidly  towards  the  vertical.  As  it  rises  again  from 
the  vertical  position,  it  moves  more  slowly,  and  the  kinetic  energy  is  changed 
into  potential  energy,  which  once  more  reaches  its  maximum,  when  the  pen- 
dulum comes  to  rest  at  the  utmost  limit  of  its  excursion.  Were  it  not  for  the 
resistances  continually  opposed  to  its  movements,  such  as  the  resistance  of  the 
air,  and  friction,  the  movement  of  the  pendulum,  due  to  the  alternating  change  of 
kinetic  into  potential  energy  and  vice  versd,  would  continue  uninterruptedly,  as 
with  a  mathematical  pendulum.  Suppose  the  swinging  ball  of  the  pendulum, 
when  exactly  in  a  vertical  position,  impinged  upon  a  resting  but  movable  sphere, 
the  potential  energy  of  the  ball  of  the  pendulum  would  be  transferred  directly  to 
the  sphere,  provided  that  the  elasticity  of  the  ball  of  the  pendulum  and  the  sphere 
were  complete;  the  pendulum  would  come  to  rest,  while  the  sphere  would  move 
onward  with  an  equal  amount  of  kinetic  energy,  provided  there  were  no  resistance 
to  its  movement.  This  is  an  example  of  the  transference  of  kinetic  energy  from 
one  body  to  another.  Lastly,  suppose  that  a  stretched  watch-spring  on  uncoiling 
causes  another  spring  to  become  coiled;  and  we  have  another  example  of  the 
transference  of  kinetic  energy  from  one  body  to  another. 

The  following  general  statement  is  deducible  from  the  foregoing 
examples : — If,  in  a  system,  the  individual  moving  masses  approach  the 
final  position  of  equilibrium,  then  in  this  system  the  sum  of  the  Jcinetio 


INTRODUCTION.  XXV 

energies  increases ;  if,  on  the  other  hand,  the  particles  move  away  from 
the  final  position  of  equilibrium,  then  the  sum  of  the  potential  energies 
is  increased  at  the  expense  of  the  kinetic  energies,  i.e.,  the  kinetic 
energies  diminish  (Briicke). 

The  pendulum,  which,  after  swinging  from  the  highest  point  of  its  excursion, 
approaches  the  vertical  position,  i.e.,  the  position  of  equilibrium  of  a  passive  pen- 
dulum, has  in  this  position  the  largest  amount  of  potential  energy;  as  it  again 
ascends  to  the  highest  point  of  its  excursion  on  the  other  side,  it  again  gradually 
receives  the  maximum  of  potential  energy  at  the  expense  of  the  gradually  diminish- 
ing movement,  and  therefore  of  the  kinetic  energy. 

3.  Heat — Its  Relation  to  Potential  and  Kinetic  Energy. — If  a  lead 
weight  be  thrown  from  a  high  tower  to  the  earth,  and  if  it  strike  an 
unyielding  substance,  the  movement  of  the  mass  of  lead  is  not  only 
arrested,  but  the  kinetic  energy  (which  to  the  eye  appears  to  be  lost), 
is  transformed  into  a  lively  vibratory  movement  of  the  atoms.  When 
the  lead  meets  the  earth,  heat  is  produced.  The  amount  of  heat  pro- 
duced is  proportional  to  the  kinetic  energy,  which  is  transformed 
through  the  concussion.  At  the  moment  when  the  lead  weight 
reaches  the  earth,  the  atoms  are  thrown  into  vibrations ;  they  impinge 
upon  each  other ;  then  rebound  again  from  each  other  in  consequence 
of  their  elasticity,  which  opposes  their  direct  juxtaposition ;  they  fly 
asunder  to  the  maximum  extent  permitted  by  the  attractive  force  of 
the  ponderable  atoms,  and  thus  oscillate  to  and  fro.  All  the  atoms 
vibrate  like  a  pendulum,  until  their  movement  is  communicated  to  the 
ethereal  atoms  surrounding  them  on  every  side,  i.e.,  until  the  heat  of 
the  heated  mass  is  "  radiated."  Heat  is  thus  a  vibratory  movement  of  the 
atoms. 

As  the  amount  of  heat  produced  is  proportional  to  the  kinetic  energy, 
which  is  transformed  through  the  concussion,  we  must  find  an  adequate 
measure  for  both  forces. 

Heat-Unit. — As  a  standard  of  measure  of  heat,  we  have  the  "heat- 
unit"  or  calorie.  The  "heat-unit"  or  calorie  is  the  amount  of  energy 
required  to  raise  the  temperature  of  1  gramme  of  water  1°  centigrade. 
The  "heat-unit"  corresponds  to  425-5  gramme-metres,  i.e.,  the  same 
energy  required  to  heat  1  gramme  of  water  TC.  would  raise  a  weight  of 
425-5  grammes  to  the  height  of  1  metre;  or,  a  weight  of  425-5  grammes, 
if  allowed  to  fall  from  the  height  of  1  metre,  would  by  its  concussion, 
produce  as  much  heat  as  would  raise  the  temperature  of  1  gramme  of 
water  TC.  The  "mechanical  equivalent''  of  the  heat-unit  is,  there- 
fore, 425-5  gramme-metres. 

It  is  evident,  that  from  the  collision  of  moving  masses,  an  immeasurable  amount 
of  heat  can  be  produced.  Let  us  apply  what  has  already  been  said  to  the  earth. 
Suppose  the  earth  to  be  disturbed  in  its  orbit,  and  suppose  further  that,  owing  to 


XXVI  INTRODUCTION. 

the  attraction  of  the  sun,  it  were  to  impinge  on  the  latter  (whereby,  according 
to  J.  R.  Mayer,  its  final  velocity  would  be  85  geographical  miles  per  second),  the 
amount  of  heat  produced  by  the  collision  would  be  equal  to  that  produced  by  the 
combustion  of  a  mass  of  pure  charcoal  more  than  5000  times  as  heavy  (Julius 
Eobert  Mayer,  Helmholtz). 

Thus,  the  heat  of  the  sun  itself  can  be  produced  by  the  collision  of  masses  of  cold 
matter.  If  the  cold  matter  of  the  universe  were  thrown  into  space,  and  there 
left  to  the  attraction  of  its  particles,  the  collision  of  these  particles  would  ulti- 
mately produce  the  light  of  the  stars.  At  the  present  time,  numerous  cosmic  bodies 
collide  in  space,  while  innumerable  small  meteors  (94,000-188,000  billions  of  kilos, 
per  minute)  fall  into  the  sun.  The  force  of  gravity  is  perhaps,  in  fact,  the  only 
source  of  all  heat  (J.  R.  Mayer,  Tyndall). 

We  have  a  homely  example  of  the  transformation  of  kinetic  energy  into  heat  in 
the  fact,  that  a  blacksmith  may  make  a  piece  of  iron  red-hot  by  hammering  it.  Of 
the  conversion  of  heat  into  kinetic  energy,  we  have  an  example  in  the  hot  watery 
vapour  (steam)  of  the  steam-engine  raising  the  piston.  An  example  of  the  conver- 
sion of  potential  energy  into  heat  occurs,  in  a  metallic  spring,  when  it  uncoils  and 
is  so  placed  as  to  rub  against  a  rough  surface,  producing  heat  by  friction. 

4.  Chemical  Affinity :  Relation  to  Heat. — ^Whilst  gravity  acts  upon 
the  particles  of  matter  without  reference  to  the  composition  of  the 
"body,  there  is  another  atomic  force  which  acts  between  atoms  of  a 
chemically  different  nature ;  this  is  chemical  affinity.  This  is  the  force, 
in  virtue  of  which  the  atoms  of  chemically-different  bodies  unite  to 
form  a  chemical  compound.  The  force  itself  varies  greatly  between  the 
atoms  of  different  chemical  bodies ;  thus,  we  speak  of  strong  chemical 
affinities  and  weak  affinities.  Just  as  we  were  able  to  estimate  the 
potential  energy  of  a  body  in  motion,  from  the  amount  of  heat  which 
was  produced  when  it  collided  with  an  unyielding  body,  so  we  can 
measure  the  amount  of  the  chemical  affinity  by  the  amount  of  heat 
which  is  formed,  when  the  atoms  of  chemically-different  bodies  unite  to 
form  a  chemical  compound.  As  a  rule,  heat  is  formed  when  separate, 
chemically-different  atoms,  form  a  compound  body.  When  in  virtue 
of  chemical  affinity,  the  atoms  of  1  kilo,  of  hydrogen  and  8  kilos,  of 
oxygen  unite  to  form  the  chemical  compound  water,  an  amount  of  heat 
is  thereby  evolved  which  is  equal  to  that  produced  by  a  weight  of 
47,000  kilos,  falling  and  colliding  with  the  earth  from  a  height  of 
1000  feet  above  the  surface  of  the  earth.  If  1  gram,  of  H  be  burned 
along  with  the  requisite  amount  of  O  to  form  water,  it  yields  34,460 
heat-units  or  calories;  and  1  gram,  carbon  burned  to  carbonic  acid 
(carbon  dioxide)  yields  8,080  heat-units.  Wherever,  in  chemical  processes, 
strong  chemical  affinities  are  satisfied,  heat  is  set  free — i.e.,  chemical  affinity 
is  changed  into  heat.  Chemical  affinity  is  a  form  of  potential  energy 
obtaining  between  the  most  different  atoms,  which  during  chemical 
processes  is  changed  into  heat.  Conversely,  in  those  chemical  processes 
where  strong  affinities  are  dissolved,  and  chemically-united  atoms 
thereby  pulled  asunder,  there  must  be  a  diminution  of  temperature,  or, 


INTRODUCTION.  XXvil 

as  it  is  said,  heat  becomes  latent — that  is,  the  energy  of  the  heat  which 
has  become  latent  is  changed  into  chemical  energy,  and  this,  after 
decomposition  of  the  compound  chemical  body,  is  again  represented  by 
the  chemical  affinity  between  its  isolated  different  atoms. 


Law  of  the  Conservation  of  Energy. 

Julius  Robert  Mayer  and  Helmholtz  have  established  the  important 
law,  that  in  a  system  which  does  not  receive  any  influence  and  impres- 
sion from  without,  the  sum  of  all  the  forces  acting  within  it  is  always  the 
same.  The  various  fm-ms  of  energy  can  be  transformed  one  into  the  other, 
so  that  Jcinetic  energy  may  be  transfm-med  into  potential  energy  and  vice  versd, 
but  there  is  never  any  part  of  the  energy  lost.  The  transformation  takes 
place  in  such  measure  that,  from  a  certain  definite  amount  of  one  form 
of  energy,  a  definite  amount  of  another  can  be  obtained. 

The  various  forms  of  energy  acting  in  organisms  occur  in  the  follow- 
ing modifications  : — 

1.  Molar  motion  (ordinary  movements),  as  in  the  movements  of  the 
whole  body,  of  the  limbs,  or  of  the  intestines,  and  even  those  observable 
microscopically  in  connection  with  cells. 

2.  Movements  of  Atoms  as  Heat. — We  know,  in  connection  with 
the  vibration  of  atoms,  that  the  number  of  vibrations  in  the  unit  of 
time  determines  whether  the  oscillations  appear  as  heat,  light,  or 
chemically-active  vibrations.  Heat-vibrations  have  the  smallest 
number,  while  chemically-active  vibrations  have  the  largest  number, 
light-vibrations  standing  between  the  two.  In  the  human  body,  we 
only  observe  heat-vibrations,  but  some  of  the  lower  animals  are  capable 
of  exhibiting  the  phenomena  of  light. 

In  the  human  organism,  the  molar  movements  in  the  indi-\ddual 
organs  are  constantly  being  transformed  into  heat,  e.g.,  the  kinetic 
energy  in  the  organs  of  the  circulation  is  transformed  by  friction  into 
heat.  The  measure  of  this  is  the  "unit  of  tcorJc"^:!  gramme-metre, 
and  the  '^iinit  of  heat  ^'^4:25'5  gramme-metres. 

3.  Potential  Energy. — The  organism  contains  many  chemical  com- 
pounds which  are  characterised  by  the  great  complexity  of  their 
constitution,  by  the  imperfect  saturation  of  their  affinities,  and  hence, 
by  their  great  tendency  to  split  up  into  simpler  bodies. 

The  body  can  transform  the  potential  energy  into  heat  as  well  as 
into  kinetic  energy,  the  latter  always  in  conjunction  with  the  former, 
but  the  former  always  by  itself  alone.  The  simplest  measure  of  the 
potential  energy  is  the  amount  of  heat,  which  can  be  obtained  by  complete 
combustion  of   the   chemical   compounds  representing   the  potential 


XXVIU  INTRODUCTION. 

energy.  The  number  of  work-units  can  then  be  calculated  from  the 
amount  of  heat  produced, 

4,  The  phenomena  of  electricity,  magnetism,  and  diamagnetism 
may  be  recognised  in  two  directions,  as  movements  of  the  smallest 
particles,  which  are  recognised  in  the  glowing  of  a  thin  wire  when  it 
is  traversed  by  strong  electrical  currents  (against  considerable  resist- 
ance), and  also  as  molar  movement,  as  in  the  attraction  or  repulsion  of 
the  magnetic  needle.  Electrical  phenomena  are  manifested  in  our 
bodies  by  muscle,  nerve,  and  glands,  but  these  phenomena  are  rela- 
tively small  in  amount  when  compared  with  the  other  forms  of  energy. 
It  is  not  improbable  that  the  electrical  phenomena  of  our  bodies 
become  almost  completely  transformed  into  heat.  As  yet  experiment 
has  not  determined  with  accuracy  a  "unit  of  electricity,"  directly 
comparable  with  the  "heat-unit"  and  the  "work-unit." 

It  is  quite  certain  that  within  the  organism,  one  form  of  energy  can 
be  transformed  into  another  form,  and  that  a  certain  amount  of  one 
form  will  yield  a  definite  amount  of  another  form;  further,  that  new 
energy  never  arises  spontaneously,  nor  is  energy,  already  present,  ever 
destroyed,  so  that  in  the  organism  the  law  of  the  conservation  of 
energy  is  continually  in  action. 


Animals  and  Plants. 

The  animal  body  contains  a  quantity  of  chemically-potential  energy 
stored  up  in  its  constituents.  The  total  amount  of  the  energy  present 
in  the  human  body  might  be  measured,  by  burning  completely  an  entire 
human  body  in  a  calorimeter,  and  thereby  determining  how  many  heat- 
units  are  produced  when  it  is  reduced  to  ashes  (see  Animal  Heat, 
p.  422). 

The  chemical  compounds  containing  the  potential  energy  are 
characterised  by  the  complicated  relative  position  of  their  atoms,  by  a 
comparatively  imperfect  saturation  of  the  affinities  of  their  atoms,  by 
the  relatively  small  amount  of  oxygen  which  they  contain,  by  their 
great  tendency  to  decomposition,  and  the  facility  with  which  they 
undergo  it. 

If  a  man  were  not  supplied  with  food,  he  would  lose  50  grammes  of 
his  body-weight  every  hour;  the  material  part  of  his  body,  which 
contains  the  potential  energy,  is  used  up,  oxygen  is  absorbed,  and  a 
continual  process  of  combustion  takes  place;  by  the  process  of  com- 
bustion, simpler  substances  are  formed  from  the  more  complex 
compounds,  whereby  potential  is  converted  into  kinetic  energy.  It  is 
immaterial  whether  the  combustion  is  rapid  or  slow ;  the  same  amount 


INTRODUCTION.  XXlX 

of  the  same  chemical  substances  always  produces  the  same  amount  of 
kinetic  energy,  i.e.,  of  heat. 

A  person  when  fasting,  experiences  after  a  certain  time,  the  dis- 
agreeable feeling  of  exhaustion  of  his  reserve  of  potential  energy, 
hunger  sets  in,  and  he  takes  food.  All  food  for  the  animal  kingdom  is 
obtained,  either  directly  or  indirectly,  from  the  vegetable  kingdom.  Even 
carnivora,  which  eat  the  flesh  of  other  animals,  only  eat  organised 
matter  which  has  been  formed  from  vegetable  food.  The  existence  of 
the  animal  kingdom  presupposes  the  existence  of  the  vegetable 
kingdom. 

All  substances,  therefore,  necessary  for  the  food  of  animals  occur  in 
vegetables.  Besides  water  and  the  inorganic  constituents,  plants 
contain,  amongst  other  organic  compounds,  the  following  three  chief  re- 
presentatives of  food-stuffs — fats,  carbohydrates,  and  proteids. 

All  these  contain  stores  of  potential  energy,  in  virtue  of  their  com- 
plex chemical  constitution. 

The  fats  contain  :-  j  ^'"'^^^-^^2^'^  =  ^f  ^  "l'^'    \  (§  251). 
(.  +  03X15(011)3    =  glycerine      ) 

The  carbohydrates  contain  : — CgHj^Og  .  .         .     (§  252). 

C.  51  •5-54-5  1 

H.   6-9-  7-3  [  ^ 

The  proteids  contain  per  cent. :—  \  K  15-2-1 7-0  [      ^iq^ 

I  0.  20-9-23-5  I       "     ^' 

[  S.    0-3-  2-0  J 

A  man,  who  takes  a  certain  amount  of  this  food  adds  thereto  oxygen 
from  the  air  in  the  process  of  respiration.  Combustion  or  oxidation 
then  takes  place,  whereby  chemically  potential  energy  is  transformed 
into  heat. 

It  is  evident,  that  the  products  of  this  combustion  must  be  bodies  of 
simpler  constitution — bodies  with  less  complex  arrangement  of  their 
atoms,  with  the  greatest  possible  saturation  of  the  affinities  of  their 
atoms,  of  greater  stability,  partly  rich^in  0,  and  possessing  either  no 
potential  energy,  or  only  very  little.  These  bodies  are  carbanic  acid 
(carbon  dioxide),  CO,;  water,  HgO;  and  as  the  chief  representative  of 
the  nitrogenous  excreta,  urea  (CO(NH2)2),  which  has  still  a  small 
amount  of  potential  energy,  but  which  outside  the  body  readily  splits 
into  CO2  and  ammonia  (NH3). 

The  human  body  is  an  organism  in  which,  by  the  phenomena  of 
oxidation,  the  complex  nutritive  materials  of  the  vegetable  kingdom, 
which  are  highly  charged  -with  potential  energy,  are  transformed  into 
simple  chemical  bodies,  whereby  the  potential  energy  is  transformed 


XXX  INTRODUCTION. 

into  the  equivalent  amount  of  kinetic  energy  (heat,  work,  electrical 
phenomena). 

But  how  do  plants  form  these  complex  food-stuffs  so  rich  in  potential 
energy?  It  is  plain,  that  the  potential  energy  of  plants  must  be 
obtained  from  some  other  form  of  energy.  This  potential  energy 
is  supplied  to  plants  by  the  rays  of  the  sun^  whose  chemical  light-rays 
are  absorbed  by  plants.  Without  the  rays  of  the  sun  there  could  be  no 
plants.  Plants  absorb  from  the  air  and  the  soil,  COg,  HgO,  NH3,  and  N, 
of  which  carbonic  acid,  water,  and  ammonia  (from  urea),  are  also  pro- 
duced by  the  excreta  of  animals.  Plants  absorb  the  kinetic  energy  of 
light  from  the  suns  rays  and  transform  it  into  potential  energy,  which  is 
accumulated  during  the  growth  of  the  plant  in  its  tissues,  and  in  the . 
food-stuffs  produced  in  them  during  their  growth.  This  formation  of 
complex  chemical  compounds  is  accompanied  by  the  simultaneous 
excretion  of  0. 

Occasionally,  kinetic  energy,  such  as  we  universally  meet  with  in  animals,  ia 
liberated  in  plants.  Many  plants  develop  considerable  quantities  of  heat  in  their 
flowers — e.g.,  the  aram  tribe.  We  must  also  remember  that,  during  the  forma- 
tion of  the  solid  parts  of  plants,  when  fluid  juices  are  changed  into  solid  masses, 
heat  is  set  free.  In  plants,  under  certain  circumstances,  0  is  absorbed,  and  CO2 
is  excreted,  but  these  processes  are  so  trivial  as  compared  with  the  typical  condi- 
tion in  the  vegetable  kingdom,  that  they  may  be  regarded  as  of  small  moment. 

Plants,  therefore,  are  organisms  which,  by  a  reduction  process,  trans- 
form simple  stable  combinations  into  complex  compounds,  whereby 
potential  solar  energy  is  transformed  into  the  chemically-potential 
energy  of  vegetable  tissues.  Animals  are  living  beings,  which,  by 
oxidation,  decompose  or  break  up  the  complex  grouping  of  atoms 
manufactured  by  plants,  whereby  potential  is  transformed  into  kinetic 
energy.  Thus,  there  is  a  constant  circulation  of  matter  and  a  constant 
exchange  of  energy  between  plants  and  animals.  All  the  energy  of 
animals  is  derived  from  plants.  All  the  energy  of  plants  arises  from 
the  sun.  Thus  the  sun  is  the  cause,  the  original  source  of  all  energy 
in  the  organism,  i.e.,  of  the  whole  of  life. 

As  the  formation  of  solar  heat  and  solar  light  is  explicable  by  the 
gravitation  of  masses,  gravity  is  joerhaps  the  original  form  of  energy  of 
aU  life. 

We  may  thus  represent  the  formation  of  kinetic  energy  in  the  animal 
body  from  the  potential  energy  of  plants.  Let  us  suppose  the  atoms  of 
the  substances  formed  in  organisms,  as  simple  small  bodies,  balls,  or 
blocks.  As  long  as  these  lie  in  a  single  layer,  or  in  a  few  layers,  upon 
the  surface,  there  is  a  stable  arrangement,  and  they  continue  to 
remain  at  rest.  If,  however,  an  artificial  tower  be  built  of  these 
blocks,  so  that  an  unstable  erection  is  produced,  and  the  same  tower 
be  afterwards  knocked  down,  then  for  this  purpose  we  require — (1) 


INTRODUCTION.  XXXI 

the  motor  power  of  the  workman  who  lifts  and  carries  the  blocks ;  (2) 
a  blow  or  other  impulse  from  without  applied  to  the  unstable  structure- 
when  the  atoms  will  fall  together,  and  as  they  fall  collide  with  each 
other  and  produce  heat.  Thus,  the  energy  employed  by  the  workman 
is  again  transformed  into  the  last-named  form  of  energy. 

In  plants,  the  complex  unstable  building  of  the  groups  of  atoms  is 
carried  on,  the  constructor  being  the  sun.  In  animals,  which  eat 
plants,  the  complex  groups  of  the  atoms  are  tumbled  down,  with  the 
liberation  of  kinetic  energy. 

Vital  Energy  and  Life. 

The  forces  which  act  in  organisms,  in  plants  and  animals  are  exactly 
the  same  as  are  recognisable  as  acting  in  dead  matter.  A  so-called 
"  vital  force,"  as  a  special  force  of  a  peculiar  kind,  causing  and  governing 
the  vital  phenomena  of  living  beings,  does  not  exist.  The  forces  of  all 
matter,  of  organised  as  well  as  unorganised,  exist  in  connection  with 
their  smallest  particles  or  atoms.  As,  however,  the  smallest  particles  of 
organised  matter  are,  for  the  most  part,  arranged  in  a  very  complicated 
way,  compared  with  the  much  simpler  composition  of  inorganic  bodies, 
so  the  forces  of  the  organism,  connected  with  the  smallest  particles, 
yield  more  complicated  phenomena  and  combinations,  whereby  it  is 
excessively  difficult  to  ascribe  the  vital  phenomena  in  organisms  to  the 
simple  fundamental  laws  of  physics  and  chemistry. 

The  Exchange  of  Material,  or  Metabolism  (Stoffwechsel)  as  a  Sign  of 
Life. — Nevertheless,  there  appears  to  be  a  special  exchange  of  matter 
and  energy  peculiar  to  living  beings.  This  consists  in  the  capacity  of 
organisms  to  assimilate  the  matter  of  their  surroundings,  and  to  work 
it  up  into  their  own  constitution,  so  that  it  forms  for  a  time  an  integral 
part  of  the  living  being,  to  be  given  off  again.  The  whole  series  of 
phenomena  is  called  Metabolism  or  StoflFwechsel,  which  consists  in  the 
introduction,  assimilation,  integration,  and  excretion  of  matter. 

We  have  already  shown,  that  the  metabolism  of  plants  and  that  of 
animals  are  quite  different.  The  processes,  as  already  described, 
are  actually  what  occur  in  the  typical  higher  plants  and  animals. 

But  there  is  a  large  group  of  organisms  which,  throughout  their 
entire  organisation,  exhibit  so  low  a  degree  of  development,  that  by 
some  observers  they  are  considered  as  undifferentiated  "  ground-forms." 
They  are  regarded  as  neither  plants  nor  animals,  and  are  the  most 
simple  forms  of  animated  matter.  Haeckel  has  called  these  organisms 
Protistce,  as  being  the  original  and  primitive  forms. 

We  must  assume  that,  corresponding  with  their  simpler  vital  condi- 
tions, their  metabolism  is  also  simpler,  but  on  this  point  we  still 
require  further  observations. 


Physiology  of  tlie  Blood. 


[The  blood  is  aptly  described  by  Claude  Bernard  as  an  internal  7nedium, 
which  acts  as  a  "  go-between  "  for  the  outer  world  and  the  tissues. 
Into  it  are  poured  those  substances  which  have  been  subjected  to  the 
action  of  the  digestive  fluids,  and  in  the  lungs  or  other  respiratory 
organs  it  receives  oxygen.  It  thus  contains  new  substances,  but  in  its 
passage  through  the  tissues  it  gives  up  some  of  these  new  substances, 
and  receives  in  exchange  certain  effete  and  more  or  less  useless  sub- 
stances which  have  to  be  got  rid  of.  Its  composition  is  thus  highly 
complex,  containing,  as  it  does,  things  both  new  and  old.  It  is  at 
once  a  great  pabulum-supplying  medium,  and  a  channel  for  getting  rid 
of  useless  materials.  As  the  composition  of  the  organs  through  which 
the  blood  flows  varies,  it  is  evident  that  its  composition  must  vary 
in  different  pa^ts  of  the  circulatory  system ;  and  it  also  varies  in  the 
same  individual  under  different  conditions.  Still,  with  slight  varia- 
tions, there  are  certain  general  physical,  histological,  and  chemical 
properties  which  characterise  blood  as  a  whole.^ 

1.  Physical  Properties  of  the  Blood. 

(1.)  Colour. — The  colour  of  blood  varies  from  a  bright  scarlet-red 
in  the  arteries  to  a  deep,  dark,  bluish-red  in  the  veins.  Oxygen  (and, 
therefore,  the  air)  makes  the  blood  bright-red ;  want  of  oxygen  makes 
it  dark.  Blood  free  from  oxygen  (and  also  venous  blood)  is  dichroic 
— i.e.,  by  reflected  light  it  appears  dark-red,  while  by  transmitted 
light  it  is  green  (Briicke). 

In  thin  layers  blood  is  opaque,  as  is  easily  shown  by  shaking  blood 
so  as  to  form  bubbles,  or  by  allowing  blood  to  fall  upon  a  plate  with 
a  pattern  on  it,  and  pouring  it  off  again.  Blood  behaves,  therefore, 
like  an  "  opaque  colour  "  (Rollett),  as  its  colouring-matter  is  suspended 
in  the  form  of  fine  particles — the  blood-corpuscles. 

Hence,  it  is  possible  to  separate  the  colouring-matter  from  the  fluid  part  of  the 
blood  by  filtration.  This  is  accomplished  by  mixing  the  blood  with  fluids  which 
render  the  blood-corpuscles  sticky  or  rough.  If  mammalian  blood  be  treated  with 
one-seventh  of  its  volume  of  solution  of  sodic  sulphate,  or  if  frog's  blood  be  mixed 
with  a  two  per  cent,  solution  of  sugar  and  filtered,  the  shrivelled  corpuscles,  now 
robbed  of  part  of  their  water,  remain  upon  the  filter. 


2  PHYSICAL  PROPERTIES  OF  THE  BLOOD. 

(2.)  Eeaction. — The  reaction  is  alkaline,  owing  to  the  presence  of 
disodic  phosphate,  NagjHjPO^  (Maly).  After  blood  is  shed,  its 
alkalinity  rapidly  diminishes,  and  this  occurs  more  rapidly  the  greater 
the  alkalinity  of  the  blood.  This  is  due  to  the  formation  of  an  acid,  in 
which,  perhaps,  the  coloured  corpuscles  take  part,  owing  to  the  decom- 
position of  their  colouring-matter.  A  high  temperature  and  the  addi- 
tion of  an  alkali  favour  the  formation  of  the  acid  (N.  Zuntz). 

The  alkalinity  is  less  in  persons  suffering  from  anaemia,  cachectic  conditions, 
and  chronic  rheumatism  (Lupine).  After  the  prolonged  use  of  soda,  the  alkali 
in  the  ash  of  blood  is  increased  (Dubelir). 

Methods. — Owing  to  the  colour  of  the  blood  we  cannot  employ  ordinary  litmus 
paper  to  test  its  reaction.  One  or  other  of  the  following  methods  may  be  used  : — 
(1.)  Moisten  a  strip  of  glazed  red  litmus  paper  with  solution  of  common  salt,  and 
dip  it  quickly  into  the  blood,  or  allow  a  drop  of  blood  to  fall  on  the  paper,  and 
rapidly  wipe  it  off  before  its  colouring-matter  has  time  to  penetrate  and  tinge  the 
paper  (Zuntz).  (2.)  Kiihne  made  a  small  cup  of  parchment  paper  which  was 
placed  in  water  in  a  watch-glass.  The  colourless  diffusate  was  afterwards  tested 
with  litmus  paper.  (3.)  Liebreich  used  thin  plates  of  plaster-of-Paris  of  a  per- 
fectly neutral  reaction.  These  are  dried,  and  afterwards  moistened  with  a  neutral 
solution  of  litmus.  When  a  drop  of  blood  is  placed  upon  the  porous  plate,  the 
fluid  part  of  the  blood  passes  into  it,  while  the  corpuscles  remain  at  the  surface. 
The  corpuscles  are  washed  off  with  water,  and  the  altered  colour  of  the  litmus - 
stained  slab  is  apparent.  [(4.)  Schafer  uses  dry  faintly-reddened  glazed  litmus 
paper,  and  on  it  is  placed  a  drop  of  blood,  which  is  wiped  off  after  a  few  seconds. 
The  place  where  the  blood  rested  is  indicated  by  a  well-defined  blue  patch  upon 
a  red  or  violet  ground.] 

The  alkaline  reaction  of  blood  is  diminished  :  (a)  By  great  muscular  exertion, 
owing  to  the  formation  of  a  large  amount  of  acid  in  the  muscles ;  {/3)  during 
coagulation ;  (y)  in  old  blood,  or  blood  dissolved  by  water  from  old  blood-stains, 
such  blood  being  usually  acid.  Fresh  cruor  has  a  stronger  alkaline  reaction  than 
serum. 

(3.)  Odour. — Blood  emits  a  peculiar  odour  {Halitus  sanguinis),  which 

differs  in  animals  and  man. 

It  depends  upon  the  presence  of  volatile  fatty  acids.  If  concentrated  sulphuric 
acid  be  added  to  blood,  whereby  the  volatile  fatty  acids  are  set  free  from  their  com- 
binations with  alkalies,  the  characteristic  odour  becomes  much  more  perceptible 
(Barruel). 

(4.)  Taste. — Blood  has  a  saline  taste,  depending  upon  the  salts  dis- 
solved in  the  fluid  of  the  blood. 

(5.)  Specific  Gravity. — The  specific  gravity  is  1,055  (extreme  limits 

1,045-1,075);   in  women    and   young  persons   it  is  somewhat   less. 

The  specific  gravity    of  the    blood-corpuscles  is   1,105,  that  of  the 

plasma  1,027.     Hence,  the  corpuscles  tend  to  sink. 

The  specific  gravity  of  the  red  blood-corpuscles  is  estimated  by  allowing  the 
corpuscles  to  subside  to  the  bottom  (which  occurs  most  readily  in  the  blood  of 
the  horse) ;  but  it  is  more  correctly  estimated  by  placing  the  blood  in  a  tall 
cylindrical  vessel,  and  setting  the  latter  in  the  radius  of  the  revolving 
disc  of  a  centrifugal  apparatus,  the  base  of  the  cylinder  being  directed  out- 
wards.    The  drinking  of  water  and  hunger  diminish  the  specific  gravity  tem- 


MICROSCOPIC  EXAMINATION   OF  THE  BLOOD.  3 

porarily,  while  thirst  and  the  digestion  of  dry  food  raise  it.  If  blood  be  passed 
through  an  organ  artificially,  its  specific  gravity  rises  in  consequence  of  the 
absorption  of  dissolved  matters  and  the  giving  off  of  water.  It  falls  after 
hfemorrhage,  and  is  less  in  badly-nourished  iudividnals. 

2.  Microscopic  Examination  of  the  Blood. 

[Blood,  when  examined  by  the  microscope,  is  seen  to  consist  of  an 
enormous  number  of  corpuscles — coloured  and  colourless — floating  in 
a  transparent  fluid,  the  plasma,  or  liquor  sanguinis.^ 

The  RED  blood-corpuscles  were  discovered  in  frog's  blood  by  Swam- 
raerdam  in  1658,  and  in  human  blood  by  Leeuwenhoek  in  1673. 

Characters  of  Human  Blood — {a)  Form. — The  human  red  blood- 
corpuscles  are  circular,  coin-shaped,  homogeneous  discs,  with  saucer-like 
depressions  on  both  surfaces,  and  with  rounded  margins;  in  other 
words,  they  are  bi-concave,  circular  discs. 

(h.)  Size. — According  to  "Welcker  the  diameter  {a  h)  is  7"7  //,*  the 
greatest  thickness  (c  (T)  1"9  ^  (Fig.  1,  C)  \i.e.,  it  is  ^jxoo  to  Tj^nro  of 
an  inch  in  diameter,  and  about  one-fourth  of  that  in  thickness]. 

The  corpuscles  are  slightly  diminished  in  size  by  septic  fever,  inanition,  after  the 
subcutaneous  injection  of  morphia,  increased  bodily  temperature,  and  CO2  ;  while 
they  are  increased  by  0,  watery  condition  of  the  blood,  cold,  consumption  of 
alcohol,  quinine,  hydrocyanic  acid,  and  acute  anfemia  (Manassein). 

A  B 


A,  Human  coloured  blood-corpuscles — 1,  seen  on  the  flat;  2,  on  edge;  3, 
rouleau  of  coloured  corpuscles  slightly  separated.  B,  Coloured  amphibian 
blood-corpuscles — 1,  seen  on  the  flat,  and  2,  on  edge.  C,  Ideal  transverse 
section  of  a  human  coloured  blood-corpuscle  magnified  5,000  times  linear ; 
a  b,  diameter ;  c  d,  thickness, 

*  The  Greek  letter  /x  represents  one-thousandth  of  a  millimetre  Ou= 0*001  mm.), 
and  is  the  sign  of  a  micro-millimetre,  or  a  micron. 


4  MICROSCOPIC  EXAMINATION  OF  THE  BLOOD. 

If  the  total  amount  of  blood  in  a  man  be  taken  at  4,400  cubic  centimetres,  the 
corpuscles  therein  contained  have  a  surface  of  2,816  square  metres,  which  is  equal 
to  a  square  surface  with  a  side  of  80  paces  ;  176  cubic  centimetres  of  blood  pass 
throuf^h  the  lungs  in  a  second,  and  the  blood-corpuscles  in  this  amount  of  blood 
have  a  superficies  of  81  square  metres,  equal  to  a  square  surface  with  a  side  of  13 
paces  (Welcker). 

(c.)  Weight. — The  weight  of  a  blood-corpuscle,  according  to  Welcker, 
is  0-00008  milligranunes. 

(d.)  Number. — According  to  Vierordt,  the  number  exceeds  5,000,000 
per  cubic  millimetre  in  the  male,  and  4.500,000  in  the  female;  so  that, 
in  10  lbs.  of  blood,  there  are  25  billions  of  corpuscles. 

The  venous  blood  of  the  small  cutaneous  veins  contains  more  red 
corpuscles  than  arterial  blood.  As  a  general  rule,  the  number  is  in 
inverse  ratio  to  the  amount  of  plasma ;  hence,  the  number  must  vary 
with  the  state  of  contraction  of  the  blood-vessels,  the  pressure-diflfusion 
currents,  and  other  conditions.     The  use  of  solid  food  increases  their 


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Apparatus  of  Malassez  for  estimating  the  number  of  blood-corpuscles.  A,  the 
melanrjeur,  or  pipette,  for  mixing  the  blood  with  the  artificial  serum,  f,  tube 
for  sucking  up  these  fluids.  B,  the  artificial  capillary  tube,  with  an  elastic 
tube,  /,  attached  for  filling  it.  C,  appearance  of  B  under  the  microscope 
when  it  is  filled  with  blood.  The  squares  are  due  to  a  piece  of  glass  divided 
into  squares,  which  is  put  in  the  ocular  of  the  microscope. 


NUMBER  OF  BLOOD-CORPUSCLES.  5 

number,  copious  draughts  of  water  reduce  it;  during  inanition  the 
number  is  relatively  increased,  because  the  blood  plasma  undergoes 
decomposition  sooner  than  the  blood-corpuscles  themselves  (Buntzen). 
The  blood  of  the  newly-born  child  contains  a  considerably  larger  number 
of  red  corpuscles  than  the  blood  of  the  mother  (Panum),  while  Hayem 
found  that  the  number  diminished  after  the  fourth  day.  In  persons  of 
robust  constitution  the  number  is  larger  than  in  the  weakly,  and  those 
who  live  in  the  country  have  more  than  those  who  live  in  town. 

(The  pathological  conditions  which  affect  the  number  of  corpuscles 
are  given  at  p.  22). 

a,  Malassez^s  Method  of  Estimating  the  number  of  Blood-Corpuscles. — The 
pointed  end  of  a  glass  pipette  (Fig.  2,  A),  the  mixer,  is  dipped  into  the  blood,  and 
by  sucking  the  elastic  tube,  /,  blood  is  drawn  into  the  tube  until  it  reaches  the 
mark,  \,  on  the  stem  of  the  pipette,  or  until  the  mark,  1,  is  reached.  The 
carefully-cleaned  point  of  the  pipette  is  dipped  into  the  artificial  serum,  and  this 
is  sucked  into  the  pipette  until  it  reaches  the  mark,  101.  The  artificial  serum 
consists  of  1  vol.  of  solution  of  gum  arable  (S.  G.  1,020)  and  3  vols,  of  a  solution 
of  equal  parts  of  sodic  sulphate  and  sodic  chloride  (S.  G.  1,020).  The  process  of 
mixing  the  two  fluids  is  aided  by  the  presence  of  a  little  glass  ball  (a)  in  the  bulb 
of  the  pipette.  If  blood  is  sucked  up  to  the  mark,  ^,  the  strength  of  the  mixture 
is  1:200;  if  to  the  mark,  1,  it  is  1:100,  A  small  drop  of  the  mixture  is 
allowed  to  run  into  the  artificial  capillary  tube  (c  c)  (the  first  portions  are  not 
used  in  order  to  obtain  a  uniform  sample  from  the  bulb  of  the  pipette).  The 
mixture  passes  by  capillarity  into  the  capillary  tube,  which,  when  full,  is  emptied 
by  blowing  through  the  thin  caoutchouc  tube,  /,  and  then  again  filled  to  f , 
and  the  mixture  sucked  into  the  middle  of  the  capillary  tube.  The  capillary  tube 
is  firmly  fixed  to  a  glass  slide  (B)  with  Canada  balsam,  and  on  it  is  inscribed  the 
following  numbers  : — 

Length.  Volume. 

COO/u  .  .  ..  .  89 

500  M  .  .  .  .  107 

400/11  .  .  .  .  134 

i.e.,  a  length  of  the  capillary  tube  of  600,  500,  and  400  m  contains  ^\,  ^J^,  rii, 
cubic  millimetre. 

In  order  to  count  the  corpuscles,  the  same  combination  of  lenses  must  always  be 
used.  Select  Hartnack'a  objective,  No.  5  (Nachet,  No.  2) ;  the  ocular  contains  a 
piece  of  glass  divided  into  100  squares.  The  tube  of  the  microscope  must  be  so 
made  that  it  can  be  pulled  out  and  in.  A  micrometer,  divided  into  x^  milli- 
metre, is  placed  upon  the  stage  of  the  microscope :  1  division,  therefore,  =  10  m 
(fi.  =  xiHj^  millimetre).  The  tube  is  now  pulled  out  until  the  outer  lines  of  the 
divided  ocular  {t  t,  i  i)  exactly  cover  600,  500,  or  400  /u.  (500  m  =  4  i^ii"-  is  most 
convenient).  A  mark  is  made  on  the  tube  of  the  microscope  to  indicate  how  far 
it  must  be  drawn  out  to  accomplish  this  object,  and,  having  been  made,  it  indicates, 
once  for  all,  how  far  the  tube  must  be  drawn  out  to  indicate  exactly  500  <«.  The 
capUlary  tube  is  then  filled  and  placed  on  the  stage,  instead  of  the  micrometer, 
when  a  picture  like  C  is  obtained.  The  length  of  the  capillary  tube,  from  tt  to  i  i, 
is  500  fx.  All  the  corpuscles  observable  between  t  t  and  i  i  are  now  counted. 
Suppose  315  corpuscles  to  be  counted  between  1 1  and  i  i,  the  number,  315,  is  then 
multiplied  by  107  (which  stands  opposite  500  on  B)  aud  also  by  100  (when  the 
mixture  of  blood  and  serum  was   1 :  100),  or  by  200  as  the  case  may  be — i.e.. 


6  NUMBER  OF  BLOOD-CORPUSCLES. 

315  X  107  X  100  =  3,370,000  blood-corpuscles  in  1  cubic  millimetre.     (After  the 
experiment  the  instruments  must  be  carefully  washed  with  distilled  water.) 

To  estimate  the  colourless  corpuscles  only,  mix  the  blood  with  10 
parts  of  0*5  per  cent,  solution  of  acetic  acid,  which  destroys  all  the  red 
corpuscles  (Thoma). 

Various  forms  of  apparatus  for  the  same  purpose  have  been  devised  by  Thoma, 
Zeiss,  Abb^,  and  Gowers. 

[The  following  is  a  description  of  Gowers'  instrument  (Fig.  3): — "The 
Hcemacytometer  consists  of — (1.)  A  small  pipette,  which,  when  filled  to  the 
mark  on  its  stem,  holds  exactly  995  cubic  millimetres.  It  is  furnished  with 
an  India-rubber  tube  and  mouthpiece  to  facilitate  filling  and  emptying.  (2.)  A 
capillary  tube  marked  to  contain  exactly  5  cubic  millimetres,  with  India-rubber 
tube  for  filling,  &c.  (3.)  A  small  glass  jar  in  which  the  dilution  is  made.  (4.)  A 
glass  stirrer  for  mixing  the  blood  and  solution  in  the  glass  jar.  (5.)  A  brass  stage 
plate,  carrying  a  glass  slip,  on  which  is  a  cell,  ^  of  a  millimetre  deep.  The  bottom 
of  this  is  divided  into  -^  millimetre  squares.  Upon  the  top  of  the  cell  rests  the 
cover  glass,  which  is  kept  in  its  place  by  the  pressure  of  two  springs  proceeding 
from  the  ends  of  the  stage  plate. " 

The  diluting  solution  used  is  a  solution  of  sodic  sulphate  in  distilled  water, 
S.  G.  1,025,  or  the  following — sodic  sulphate,  104  grains;  acetic  acid,  1  drachm; 
distilled  water,  4  ozs. 


Fig.  3. 

Gowers'  apparatus,  made  by  Hawksley,  London.  A,  Pipette  for  measuring  the 
diluting  solution.  B,  Capillary  tube  for  measuring  the  blood.  C,  Cell  with 
divisions  on  the  floor,  mounted  on  a  slide,  to  which  springs  are  fixed  to  secure 
the  cover  glass.  I),  Vessel  in  which  the  solution  is  made.  E,  Spud  for 
mixing  the  blood  and  solution.     F,  Guarded  spear-pointed  needle. 

"  995  cubic  millimetres  of  the  solution  are  placed  in  the  mixing  jar;  5  cubic 
millimetres  of  blood  are  drawn  into  the  capillary  tube  from  a  puncture  in  the 


HISTOLOGY  OF  THE  RED  BLOOD-CORPUSCLES.  7 

finger,  and  tlieu  blown  into  the  solution.  The  two  fluids  are  well  mixed  by 
rotating  the  stirrer  between  the  thumb  and  finger,  and  a  small  drop  of  this  dilution 
is  placed  in  the  centre  of  the  cell,  the  covering  glass  gently  put  upon  the  cell,  and 
secured  by  the  two  springs,  and  the  plate  jjlaced  upon  the  stage  of  the  microscope. 
The  lens  is  then  focussed  for  the  squares.  In  a  few  miuutes  the  corpuscles  have 
sunk  to  the  bottom  of  the  cell,  and  are  seen  at  rest  on  the  squares.  The  number 
in  ten  squares  is  then  counted,  and  this,  multiplied  by  10,000,  gives  the  number 
in  a  cubic  millimetre  of  blood. " 

Welcker  attempted  to  ascertain  the  number  of  corpuscles  by  estimating  the 
colouring-power  of  the  blood.  His  method  was  not  exact,  but  other  observers 
have  constructed  apparatus  for  determining  the  amount  of  hiemoglobiu. 

(e.)  Ked  blood-corpuscles  are  characterised  by  their  great  elasticity, 
FLEXIBILITY,  and  SOFTNESS.  [The  elastic  property  is  shown  by  the 
great  extent  to  which  red  corpuscles  still  within  the  circulation  may  be 
distorted,  and  yet  resume  their  original  form  as  soon  as  the  pressure 
is  removed.] 


3.  Histology  of  the  Human  Red  Blood- Corpuscles. 

When  observed  singly,  blood-corpuscles  have  a  yellow  colour  with 
a  slight  tinge  of  green ;  they  seem  to  be  devoid  of  an  envelope,  are 
certainly  non-nucleated,  and  appear  to  be  homogeneous  throughout. 
Each  corpuscle  consists  (1.)  of  a  fmmeworic,  an  exceedingly  pale,  trans- 
parent, soft  protoplasm — the  stroma  (RoUett);  and  (2.)  of  the  red 
pigment,  or  haemoglobin,  which  impregnates  the  stroma,  much  as 
fluid  passes  into  and  is  retained  in  the  interstices  of  a  bath-sponge. 
Some  observers  (Bottcher,  Eberhardt,  Strieker),  maintain  that  the 
corpuscles  contain  a  nucleus,  but  this  is  certainly  a  mistake. 

4.  Effects  of  Reagents. 

(A.)  Vital  Phenomena. — Blood-corpuscles  contained  in  shed  blood — 
or  even  in  defibrinated  blood,  when  it  is  reintroduced  into  the  circula- 
tion— retain  their  vitality  and  functions  undiminished.  Heat  acts 
powerfully  on  their  vitality,  for  if  blood  be  heated  to  52°C.,  the 
vitality  of  the  red  corpuscles  is  extinguished.  Mammalian  blood  may 
be  kept  for  four  or  five  days  in  a  vessel  under  iced  Avater,  and  still 
retain  its  functions ;  but  if  it  be  kept  longer,  and  reintroduced  into 
the  circulation,  the  corpuscles  rapidly  break  up — a  proof  that  they 
have  lost  their  vitality  (Landois).  Blood  freshly  shed  from  an  artery, 
frequently  shows  a  transformation  of  the  corpuscles  into  a  peculiar 
mulberry-shape.  [This  is  the  so-called  crenatiou  of  the  coloured  cor- 
puscles. It  is  produced  by  poisoning  with  Calabar  bean  (T.  E.  Fraser), 
and  also  by  the  addition  of  a  2  per  cent,  solution  of  common  salt].    The 


8  HISTOLOGY  OF  THE  RED   BLOOD-CORPUSCLES. 

blood  of  many  persons  crenates  spontaneously — a  condition  ascribed 
to  an  active  contraction  of  the  stroma  (Klebs),  but  it  is  doubtful  if 
this  is  the  cause.  Max  Schultze  observed  that  the  red  corpuscles 
of  the  embryo-chick  undergo  active  contraction. 

(B.)  External  Characters. — Many  agents  affect  the  external  char- 
acters of  the  corpuscles. 

(a.)  The  Colour  is  changed  by  many  gases,  0  makes  blood  scarlet, 
want  of  0  renders  it  dark  bluish-red,  CO  makes  it  cherry-red,  NO 
violet-red.  There  is  no  difference  between  the  shape  of  corpuscles  in 
arterial  and  venous  blood,  as  was  supposed  by  Harless.  All  reagents 
(e.g.,  a  concentrated  solution  of  sodic  sulphate),  which  cause  great 
shrinking  of  the  coloured  corpuscles,  produce  a  very  bright  scarlet  or 
brick-red  colour  (Bartholinus,  1661).  The  red  colour  so  produced 
is  quite  different  from  the  scarlet-red  of  arterial  blood.  Eeagents 
which  render  blood-corpuscles  globular  darken  the  blood,  e.g.,  water, 
[The  contrast  is  very  striking,  if  we  compare  blood  to  which  a  10  per 
cent,  solution  of  common  salt  has  been  added  with  blood  to  which 
water  has  been  added.  With  reflected  light  the  one  is  bright-red, 
and  the  other  a  very  dark  deep  crimson,  almost  black.] 

(b.)  Change  of  Position  and  Form. — A  very  common  phenomenon 
in  shed  blood  is  the  tendency  of  the  corpuscles  to  run  into  rouleaux 
(Fig.  1,  A,  3). 

Conditions  that  increase  the  coagulability  of  the  blood  favour  this  phenomenon, 
which  is  ascribed  by  Dogiel  to  the  attraction  of  the  discs  and  the  formatioa  of  a 
sticky  siibstance.  [The  cause  of  the  arrangement  of  the  red  corpuscles  into 
rouleaux  is  by  no  means  clear.  They  may  be  detached  from  each  other  by  gently 
touching  the  cover-glass,  but  the  rouleaux  may  reform.  Lister  suggested  that 
the  surfaces  of  the  corpuscles  were  so  altered  that  thej"-  became  adhesive,  and  thus 
cohered.  Norris  has  made  some  ingenious  experiments  with  corks  weighted  with 
tacks  or  pins,  so  as  to  produce  partial  submersion  of  the  cork  discs.  These  discs 
rapidly  cohere,  owing  to  capillarity,  and  form  rouleaux.  If  the  discs  be  com- 
pletely submerged  they  remain  apart,  as  occurs  with  unaltered  blood-corpusclea 
within  the  blood-vessels.  If,  however,  the  corpuscles  be  dipped  in  petroleum, 
and  then  placed  in  water,  rouleaux  are  formed].  If  reagents  which  cause  the 
corpuscles  to  swell  up  be  added  to  the  blood,  the  corpuscles  become  globular  and 
the  rouleaux  break  up.  According  to  E.  Weber  and  Suchard,  the  uniting  medium 
is  not  fibrin  (although  it  may  sometimes  assume  a  fibrous  form),  but  belongs  to  the 
peripheral  layer  of  the  corpuscles. 

(c.)  The  Changes  of  Form  which,  after  blood  is  shed,  the  red  corpuscles 
undergo  until  they  are  gradually  dissolved,  are  important.  Some  reagents 
rapidly  produce  this  series  of  events — e.g.,  the  discharge  of  a  Leyden  jar 
causes  the  corpuscles  to  crenate,  so  that  their  surfaces  are  beset  with 
large  or  small  projections  (Fig.  4,  c,  d,  e,  g,  h);  it  also  causes  the  corpuscles 
to  assume  a  spherical  form  {i,i),  when  they  are  smaller  than  normal. 
The  corpuscles  so  altered  are  sticky,  and  run  together  like  drops  of  oil, 


CHANGES   IN   THE  FORM  OF  THE  RED   BLOOD-CORPUSCLES.  9 

forming  larger  spheres.  The  prolonged  action  of  the  electrical  spark 
causes  the  haemoglobin  to  separate  from  the  stroma  ik),  whereby  the 
fluid  part  of  the  blood  is  reddened,  while  the  stroma  is  recognisable 
only  as  a  faint  shadow  (l).  Similar  forms  are  to  be  found  in  decom- 
posing blood,  as  well  as  after  the  action  of  many  other  reagents. 


Fig.  4. 

Red  blood-corpuscles,  showing  various  changes  of  shape — a,  h,  normal  human  red 
corpuscles,  with  the  central  depression  more  or  less  in  focus;  c,  d,  e,  mulberry 
forms;  g,  h,  crenated  corpuscles;  k,  pale  decolourised  corpuscles;  I,  stroma; 
/,  a  frog's  blood- corpuscle,  partly  shrivelled,  owing  to  the  action  of  a  strong 
saline  solution. 


Action  of  Heat. — When  blood  is  heated,  on  a  warm  stage,  to  52°C. 
the  corpuscles  begin  to  undergo  remarkable  changes.  Some  of  them 
become  spherical,  others  biscuit-shaped  ;  some  are  perforated,  while  in 
others  small  portions  become  detached  and  swim  about  in  the  surround- 
ing fluid,  a  proof  that  heat  destroys  the  histological  individuality  of 
the  corpuscles  (Max  Schultze).  If  the  heat  be  continued,  the  corpuscles 
are  ultimately  dissolved. 

Cytozoon  or  Wiirmchen— Gaule's  Experiment.— The  following  remarkable 

observation  made  by  Gaule  deserves  mention  here : — A  few  drops  of  freshly- 
shed  frog's  blood  are  mixed  with  5  cc,  of  0'6  per  cent,  solution  of  common  salt, 
and  the  mixture  defibrinated  by  shaking  it  along  with  a  few  cc.  of  mercury.  A 
drop  of  the  defibrinated  blood  is  examined  on  a  hot  stage  (30°-32°C.)  under  a 
microscope,  when  a  protoplasmic  mass,  the  so-called  "wiirmchen,"  escapes  with 
a  lively  movement  from  many  corpuscles,  and  ultimately  dissolves.  Similar 
"cytozoa"  were  discovered  by  Gaule  in  the  epithelium  of  the  cornea,  of  the 
stomach  and  intestine,  in  connective  tissue,  in  most  of  the  large  glands,  and  in  the 
retina  (frog,  triton).  In  mammals  also  he  found  similar  but  smaller  structures. 
Most  probably  these  structures  are  parasitic  in  their  nature,  as  suggested  by 
Ray  Lankester,  who  called  the  parasite  Drepanklium  ranarum. 

If  a  finger  moistened  with  blood  be  rapidly  drawn  across  a  warm 
slip  of  glass,  so  that  the  fluid  dries  rapidly,  very  remarkable  corpuscle- 
shapes,  showing  their  great  ductility  and  softness,  are  observed  under 
the  microscope. 


10  LAKE-COLOURED   BLOOD. 

If  blood  be  mixed  with,  concentrated  gum,  and  if  concentrated  salt  solution  be 
added  to  it  under  tlie  microscope,  the  corpuscles  assume  elongated  forms 
(Lindwurm).  Similar  forms  are  obtained  by  mixing  blood  with  an  equal  volume 
of  gelatine  at  36°C.,  allowing  it  to  cool,  and  then  making  sections  of  the  coagulated 
mass  (RoUett).  The  corpuscles  may  be  broken  up  by  pressing  firmly  on  the 
cover-glass.     In  all  these  experiments  no  trace  of  an  envelope  is  observed. 

6.  Preparation  of  the  Stroma— Making  Blood 
"Lake-Coloured." 

There  are  many  reagents  which  separate  the  hsemoglobin  from  the 
stroma.  The  heemoglobin  dissolves  in  the  serum;  the  blood  then 
becomes  transparent,  as  it  contains  its  colouring  matter  in  solution,  and 
hence  it  is  called  "  lake-coloured  "  by  Eollett.  Lake-coloured  blood  is 
dark-red.  The  aggregate  condition  of  the  haemoglobin  is  not  altered, 
when  the  corpuscles  are  dissolved — it  only  changes  its  place,  leaving  the 
stroma  and  passing  into  the  serum.  Hence,  the  temperature  of  the 
blood  is  not  lowered  thereby  (Landois).  To  obtain  a  large  quantity 
of  the  stroma,  add  ten  volumes  of  a  solution  of  common  salt  {1  vol. 
concentrated  solution,  and  15  to  20  vols,  of  water)  to  one  volume  of 
defibrinated  blood,  when  the  stromata  are  thrown  down  as  a  whitish 
precipitate. 

The  following  reagents  cause  a  separation  of  the  stroma  from  the  haemo- 
globin : — 

(a.)  Physical  Agents. — l-  Heating  the  blood  to  60°C.  (Schultze);  the  tempera- 
ture, however,  varies  for  the  blood  of  different  animals.  2.  Repeated  freezing 
and  thawing  of  the  blood  (Eollett).  3.  Sparks  from  an  electrical  machine  (but 
not  after  the  addition  of  salts  to  the  blood)  (Eollett);  the  constant  and  induced 
currents  (Neumann). 

(&.)  Chemically  active  Substances  produced  within  the  Body.— 4.  Bile 

(Hiinefeld),  or  bile  salts  (Plattner,  v.  Dusch).  5.  Serum  of  other  species  of 
animals  (Landois);  thus  dog's  serum  and  frog's  serum  dissolve  the  blood-corpuscles 
of  the  rabbit  in  a  few  minutes.  6.  The  addition  of  lake-coloured  blood  of  many 
species  of  animals  (Landois). 

(c.)  Other  Chemical  Eeagents.— 7.  Water.  8.  Conduction  of  vapour  of 
chloroform  (BOttcher);  ether  (v.  Wittich);  amyls,  small  quantities  of  alcohol 
(Eollett);  thymol  (Marchand);  nitrobenzol,  ethylic  ether,  aceton,  petroleum 
ether,  etc.  (L.  Lewin).  9.  Antimonuretted  hydrogen,  arseniuretted  hydrogen ; 
carbon  disulphide  (Hiinefeld,  Hermann);  boracic  acid  (2  per  cent.),  added  to  amphi- 
bian blood,  causes  the  red  mass  (which  also  encloses  the  nucleus  when  such  is  pre- 
sent), the  so-called  zooid,  to  separate  from  the  cecoid.  The  zooid  may  shrink  from 
the  periphery  of  the  corpuscle,  or  it  may  even  pass  out  of  the  corpuscle  altogether 
(Brltcke) ;  Briicke  regards  the  stroma  in  a  certain  sense  as  a  house,  in  which  the 
remainder  of  the  substance  of  the  corpuscle,  the  chief  part  endowed  with  vital 
phenomena,  lives.  11.  Strong  solutions  of  acids  dissolve  the  corpuscles;  more 
dilute  solutions  cause  precipitates  in  the  htemoglobin.  This  is  easily  seen  with 
carbolic  acid  (Hiils  and  Landois;  Stirling  and  Eannie).  12.  Alkalies  of  moderate 
strength  cause  sudden  solution.  A  10  per  cent,  solution  of  potash,  placed  at  the 
margin  of  a  cover-glass,  shows  the  process  of  solution  going  on  under  the  micro- 


FORM  AND  SIZE  OF  THE  BLOOD-CORPUSCLES. 


11 


scope.     At  first  the  corpuscles  become  globular,  and  so  appear  smaller,  but  after- 
wards they  burst  like  soap-bubbles. 

[Tannic  Acid.  — A  freshly  prepared  solution  of  tannic  acid  has  a  remarkable 
eflfect  on  the  coloured  blood-corpuscles  of  man  and  animals  —  causing  a  separa- 
tion of  the  hcemoglobin  and  the  stroma.  The  usual  effect  is  to  produce  one  or 
more  granular  buds  of  ha3moglobin  on  the  side  of  the  corpuscles ;  more  rarely 
the  hsemoglobin  collects  around  the  nucleus,  if  such  be  present  (W.  Roberts).] 

[Ammonium  or  Potassium  Sulpho-cyanide  removes  the  haemoglobin,  and 

reveals  a  reticular  structure — iwira-nuclear  plexus  of  fibrils  (Stirling  and  Eannie).] 

The  quantity  of  gases  contained  in  the  blood-corpuscles  exercises 
an  important  influence  on  their  solubility.  The  corpuscles  of  venous 
blood,  which  contains  much  CO.^,  are  more  easily  dissolved  than 
those  of  arterial  blood;  while  between  both  stands  blood  containing 
CO  (Landois,  Litterski).  When  the  gases  are  completely  removed 
from  the  blood,  it  becomes  lake-coloured. 


6.  Form  and  Size  of  the  Blood-Corpuscles  of 
Different  Animals. 

All  mammals  (with  the  exception  of  the  camel,  llama,  alpaca,  and 
their  allies),  and  the  cyclostomata  amongst  fishes — e.g.,  Petromyzon, 
possess  circular  disc-shaped  corpuscles. 

Elliptical  corpuscles  without  a  nucleus  are  found  in  the  above-named 
mammals,  while  all  birds,  reptiles,  amphibians  (Fig.  1,  B,  1,  2),  and  fishes 
(except  cyclostomata)  have  nucleated  elliptical  bi-convex  corpuscles. 


Size  (m  =  0-001  Millimetre) 


Of  the  Disc-shaped 
Corpuscles. 


Of  the  Elliptical  Corpuscles. 


Short  Diameter. 


Long  Diameter. 


Elephant, 

Man,    . 

Dog,      . 
Rabbit, 
Cat,  .     . 
Sheep,  . 
Goat, 


.  0-0094  Mm. 
.0-0077,, 

.  0-0073  ,, 
.  0-0069  ,, 
.  0-0065  ,, 
.  0-0050  „ 
.  0-0041   „ 


Llama,    0-0040  Mm. 
Dove,      0-0065  ,, 
Frog,       0-0157   „ 
Triton,    0-0195   „ 
Proteus,  0-035     ,, 


0-0080  Mm, 
0-0147   „ 
0-0223   „ 
0-0293   „ 
0-058     ,, 


Musk-deer,  0-0025 


The  corpuscles  of   Amphiuma  are  nearly   one- 
third  larger  than  those  of  Proteus  (Riddel). 


Amongst  vertebrates,  amphioxus  has  colourless  h\oo(\.— invertebrates  generally 
have  colourless  blood,  with  colourless  corpuscles ;  but  the  earth-worm,  and  the 
larva  of  the  large  gnats,  &c.,  have  red  blood  whose  plasma  contains  htemoglobin, 
while  the  blood-corpuscles  themselves  are  colourless. 

[Elaborate  measurements  of  the  blood-corpuscles  have  been  made  in 


1^  ORIGIN   OF  THE  RED  BLOOD-CORPtJSCLES. 

this  country  by  Gulliver,  but  the  relative  size  may  be  best  appreciated 
by  compariug  the  corpuscles  from  various  vertebrates.] 

Many  invertebrates  possess  red,  violet,  brown,  or  green  opalescent  blood  with 
colourless  corpuscles  (amoeboid  cells).  In  cephalopods,  and  some  crabs,  the  blood 
is  blue,  owing  to  the  presence  of  a  colouring-matter  (Hcemo-cyanin)  which  con- 
tains copper,  and  combines  with  0  (Bert,  Eabuteau  &  Papillon,  Fr^d^ricq,  and 
Krukenberg).  The  large  blood-corpuscles  of  many  amphibia,  e.gr.,  amphiuma,  are 
visible  to  the  naked  eye.  The  blood-corpuscles  of  the  frog  contain,  in  addition  to 
a  nucleus,  a  nucleolus  (Auerbach,  Eanvier),  [and  the  same  is  true  of  the  coloured 
corpuscles  of  the  newt  (Stirling).  The  nucleolus  is  revealed  by  acting  on  the 
corpuscles  with  dilute  alcohol  (I,  alcohol;  2,  water;  E-anvier's  '^  alcool  au  iiers").] 
It  is  evident  that  the  larger  the  blood-corpuscles  are,  the  smaller  must  be  the  number 
and  total  superficies  of  corpuscles  in  a  given  volume  of  blood.  In  birds,  how- 
ever, the  number  is  relatively  larger  than  in  other  classes  of  vertebrates,  notwith- 
standing the  larger  size  of  their  corpuscles  ;  this,  doubtless,  has  a  relation  to  the 
very  energetic  metabolism  that  takes  place  in  birds  (Malassez). 

Amongst  mammals,  carnivora  have  more  blood-corpuscles  than  herbivora. 
Welcker  has  ascertained  that  goat's  blood  contains  9,720,000  corpuscles  per  cubic 
millimetre;  the  llama's,  13,000,000;  the  bullfinch's,  3,600,000;  the  lizard's, 
1,420,000;  the  frog's,  404,000;  the  proteus',  36,000.  In  liyhernating  animals, 
Vierordt  found  that  the  number  of  corpuscles  diminished  from  7,000,000  to 
2,000,000  per  cubic  millimetre  during  hybernation. 


7.  Origin  of  the  Red  Blood-Corpuscles. 

(A.)  Origin  of  the  Nucleated  Red  Corpuscles  during  Embryonic 
Life. — Blood-corpuscles  are  developed  in  the  fowl  during  the  first  days 
of  embryonic  life.  [They  appear  in  groups  within  the  large  branched 
cells  of  the  mesoblast,  in  the  vascular  area  of  the  blastoderm  outside 
the  developing  body  of  the  chick  or  embyro,  where  they  form  the 
"  blood-islands  "  of  Pander.  The  mother-cells  form  an  irregular  net- 
work by  the  union  of  the  processes  of  adjoining  cells,  and  meantime 
the  central  masses  split  up,  and  the  nuclei  multiply.  The  small 
nucleated  masses  of  protoplasm,  which  represent  the  blood-corpuscles, 
acquire  a  reddish  hue,  while  the  surrounding  protoplasm,  and  also  that 
of  the  processes,  becomes  vacuolated  or  hollowed  out,  constituting  a 
branching  system  of  canals ;  the  outer  part  of  the  cells  remaining  with 
their  nuclei  to  form  the  waUs  of  the  future  blood-vessels.  A  fluid 
appears  within  this  system  of  branched  canals  in  which  the  corpuscles 
lie,  and  gradually  a  communication  is  established  with  the  blood- 
vessels developed  in  connection  with  the  heart.] 

[According  to  Klein,  the  nuclei  of  the  protoplasmic  wall  may  also 
proliferate,  and  give  rise  to  new  corpuscles,  which  are  washed  away  to 
form  blood-corpuscles.]  At  first  the  corpuscles  are  devoid  of  pigment, 
nucleated,  globular,  larger  and  more  irregular  than  the  permanent 
corpuscles,  and  they  also  exhibit  amoeboid  movements.     They  become 


ORIGIN  OF  THE    RED  BLOOD-CORPUSCLES.  13 

coloured,  retain  their  nucleus,  and  are  capable  of  undergoing  multipli- 
cation by  division ;  and,  in  fact,  Remak  observed  all  the  stages  of  the 
process  of  division.  The  process  of  division  is  best  seen  from  the  3rd 
— 5th  day  of  incubation.  Increase  by  division  also  takes  place  in  the 
larvae  of  the  salamander,  triton,  and  toad  (Flemming,  Peremeschko). 

After  the  liver  is  developed,  blood-corpuscles  seem  to  be  formed  in  it 
(E.  H.  Weber,  KoUiker).  Protoplasmic,  nucleated,  colourless  cells  are 
carried  by  the  vena  porta  from  the  spleen  into  the  liver,  where  they 
take  up  pigment.  Neumann  found  in  the  liver  of  the  embryo  proto- 
plasmic cells  containing  red  blood-corpuscles.  The  spleen  is  also 
regarded  as  a  centre  of  their  formation,  but  this  seems  to  be  the  case 
only  during  embryonic  life  (Neumann).  Here  the  red  corpuscles  are 
said  to  arise  from  yellow,  round,  nucleated  cells,  which  represent 
transition  forms.  Foa  and  Salvioli  found  red  corpuscles  forming 
endogenously  within  large  protoplasmic  cells  in  lymphatic  glands.  In 
the  later  period  of  embryonic  life,  the  characteristic  non-nucleated 
corpuscles  seem  to  be  developed  from  the  nucleated  corpuscles.  The 
nucleus  becomes  smaller  and  smaller,  breaks  up,  and  gradually  dis- 
appears. In  the  human  embryo  at  the  fourth  week  only  nucleated 
corpuscles  are  found ;  at  the  third  month  their  number  is  still  i-i-  of 
the  total  corpuscles,  while  at  the  end  of  foetal  life  nucleated  blood- 
corpuscles  are  very  rarely  found.  Of  course,  in  animals  with  nucleated 
blood-corpuscles,  the  nucleus  of  the  embryonic  blood-corpuscles  remains. 

(B.)  Development  of  Blood-Vessels,  Formation  of  Blood- Vessels  and 
Blood-Corpuscles  during  Post-embryonic  Life.  —  Kolliker  assumed 
that,  in  the  tail  of  the  tadpole,  capillaries  are  formed  by  the  anasto- 
moses of  the  processes  of  branched  and  radiating  connective  tissue- 
corpuscles.  These  corpuscles  lose  their  nuclei  and  protoplasm,  become 
hollowed  out,  join  with  neighbouring  capillaries,  and  thus  form  new 
blood-channels.  Von  Golubew,  on  the  other  hand,  opposes  this  view. 
He  assumes  that  the  blood  capillaries  in  the  tail  of  the  tadpole  give  off 
solid  buds  at  different  places,  which  grow  more  and  more  into  the 
surrounding  tissues,  and  anastomose  with  each  other ;  their  protoplasm 
and  contents  disappearing,  they  become  hollow  and  a  branched 
system  of  capillaries  is  formed  in  the  tissues.  Ranvier,  be  it  remarked, 
noticed  the  same  mode  of  growth  in  the  omentum  of  newly-born 
kittens. 

The  latter  observer  has  recently  studied  the  development  of  blood- 
vessels and  blood-corpuscles  in  the  omentum  of  young  rabbits.  These 
animals,  when  a  week  old,  have,  in  their  omentum,  little  white  or 
milk  spots  ("  taches  laiteiises,"  Ranvier),  in  which  lie  "  vaso-formative  " 
cells,  i.e.,  highly  refractive  cells  of  variable  shape,  with  long  cylindrical 
protoplasmic  processes  (Fig.  5).     In  its  refractive  power  the  protoplasm 


u 


ORIGIN   OF  THE   RED   BLOOD-CORPUSCLES. 


of  these   cells   resembles  that   of   lymph- corpuscles.      Long  rod-like 

nuclei  lie  within  these 
cells  (K,  K),  and  also 
red  blood  -  corpuscles 
(r,  r),  and  both  are  sur- 
rounded with  proto- 
plasm. These  vaso- 
formative cells  give  off 
protoplasmic  points 
and  processes  (a,  a), 
some  of  which  end 
free,  while  others  form 
a  network.  Here  and 
there  elongated  con- 
nective tissue-corpus- 
cles lie  on  the  branches, 
and    ultimately    form 


Formation  of  red  blood-corpuscles  within  "vaso- 
formative cells,"  from  the  omentum  of  a  rabbit 
seven  days  old.  r,  r,  the  formed  corpuscles,  K,  K, 
nuclei  of  the  vaso-formative  cell,  a,  a,  processes 
which  ultimately  unite  to  form  capillaries. 


the  adventitia  of  the  blood-vessel. 

The  vaso-formative  cells  have  many  forms :  they  may  be  elongated 
cylinders  ending  in  points,  or  more  round  and  oval,  resembling 
lymph  cells,  or  they  may  be  modified  connective  tissue-corpuscles,  as 
observed  by  Schafer  in  the  subcutaneous  tissue  of  young  rats.  These 
cells  are  always  the  seat  of  origin  of  non-nucleated  red  blood-corpuscles, 
which  arise  in  the  protoplasm  of  vaso-formative  cells,  as  chlorophyll 
grains  or  starch  granules  arise  within  the  cells  of  plants.  The 
corpuscles  escape  and  are  washed  into  the  circulation,  when  the  cells 
form  connections  with  the  circulatory  system  by  means  of  their  pro- 
cesses. It  is  probable  that  the  vessels  so  formed  in  the  omentum  are 
only  temporary.  May  it  not  be  that  there  are  many  other  situations 
in  the  body  where  blood  is  regenerated  ? 

[The  observations  of  Schafer  also  prove  the  intra-cellular  origin  of 
red  blood-corpuscles,  and  although  this  mode  usually  ceases  before 
birth,  still  it  is  found  in  the  rat  at  birth.  The  protoplasm  of  the 
subcutaneous  connective  tissue-corpuscles,  which  are  derived  from  the 
mesoblast,  has  in  it  small  coloured  globules  about  the  size  of  a 
coloured  corpuscle.  The  mother-cells  elongate,  become  pointed  at 
their  ends,  and  unite  with  processes  from  adjoining  cells.  The  cells 
become  vacuolated ;  fluid  or  plasma,  in  which  the  liberated  corpuscles 
float,  appears  in  their  interior,  and  ultimately  a  communication  is 
established  with  the  general  circulation.] 

Similar  observations  have  been  made  by  Neumann  in  the  embryonic  liver ;  by 
Wissotzky  in  the  rabbit's  amnion ;  by  Klein  in  the  embryo  chick ;  and  by  Leboucq 
and  Hayem  in  various  animals ;  all  of  which  go  to  show  that  at  a  certain  early 


ORIGIN   OF  THE   RED  BLOOD-CORPUSCLES.  15 

period  of  development  blood-corpuscles  ai-e  formed  within  other  large  cells  of  the 
mesoblast,  and  that  part  of  the  protoplasm  of  these  blood-forming  cells  remains  to 
form  the  wall  of  the  future  blood-vessel. 

(C.)  Later  Formation  of  Eed  Blood-Corpuscles. — There  is  much 
diversity  of  opinion  as  to  how  coloured  blood-corpuscles  are  formed  in 
mammals  at  a  later  period.  [They  have  been  described  as  derived  from 
colourless  corpuscles,  one  set  of  observers  (including  Kolliker)  main- 
taining that  the  nucleus  of  these  corpuscles  disappears,  while  the 
peri-nuclear  portion  remains,  becomes  flattened  and  coloured,  and 
assumes  the  characters  of  the  mammalian  blood-corpuscles.  On  the 
other  hand,  other  observers  (including  Wharton  Jones,  Gulliver,  Busk, 
Huxley,  and  Balfour)  are  of  opinion  that  the  nucleus  becomes  pigmented, 
and  forms  the  future  blood-corpuscle.  It  is  still  doubtful,  however, 
whether  coloured  corpuscles  are  developed  in  either  of  these  ways.] 
Neumann  and  Bizzozero  described  peculiar  corpuscles  occurring  in  the 
red  marrow  of  bone,  which  they  maintain  become  developed  into 
coloured  blood-corpuscles,  undergoing  a  series  of  changes,  and  forming 
a  series  of  intermediate  forms,  which  may  be  detected  in  the  red 
marrow.  Bizzozero  holds  that  it  is  the  nucleus  of  the  marrow-cell 
which  is  coloured,  while  Neumann  thinks  it  is  the  perinuclear  part 
which  becomes  coloured,  and  forms  the  blood-corpuscle.  Schafer's 
observations  on  the  red  marrow  of  the  guinea-pig  rather  tend  to  con- 
firm Neumann's  view. 

These  transition  cells  are  said  by  Erb  to  be  more  numerous  after 
severe  haemorrhage,  the  number  of  them  occurring  in  the  blood 
corresponding  with  the  energy  of  the  formative  process.  In  dogs 
and  guinea-pigs  which  he  had  rendered  an?emic,  Bizzozero  found  in  the 
marrow  and  spleen  nucleated  red  blood-corpuscles,  which  increased  by 
division. 

According  to  Neumann,  the  bone-marrotv  of  adults  contains  all  transi- 
tion forms,  from  nucleated  coloured  corpuscles  to  true  red  blood- 
corpuscles.  After  copious  hsemorrhage,  these  transition  forms  appear 
in  numbers  in  the  blood-stream. 


Fed  or  blood-forming  marrow  occurs  in  the  bones  of  the  skull,  and  in  most  of  the 
bones  of  the  trunk,  while  the  bones  of  the  extremities  either  contain  yellow 
marrow  (which  is  essentially  fatty  in  its  nature),  or,  at  most,  it  is  only  the  heads 
of  the  long  bones  that  contain  red  marrow.  Where  the  blood  regeneration  process 
is  very  active,  however,  the  yellow  marrow  may  be  changed  into  red,  even  through- 
out all  the  bones  of  the  extremities  (Neumann). 

Rindiieisch  also  regards  the  connective  substance  of  the  red  marrow  and  the 
spleen  as  the  mother-tissue  of  the  red  blood-corpuscles,  the  connective  substance 
or  the  hgematogenous  connective  tissue  either  temporarily  or  permanently  forming 
red  blood-corpuscles.  Once  the  red  corpuscles  are  formed,  they  easily  enter  the 
blood-stream,  as  the  capillaries  and  veins  of  the  red  marrow  have  either  no  walls 


16  DECAY  OF  THE  RED  BLOOD-CORPUSCLES. 

(Hoyer,  KoUmann),  or  exceedingly  thin  perforated  walls.  Similar  conditions 
obtain  in  the  spleen. 

Bizzozero  and  Torre  found  that  after  severe  haemorrhage  in  birds,  the  marrow  of 
the  bones  contained  globular,  granular,  nucleated  cells,  whose  protoplasm  was 
coloured  with  hEemoglobin,  while  between  these  and  the  oval  biconvex  nucleated 
corpuscles  of  the  bird,  there  were  numerous  transition  stages.  The  spleen  of  the 
bird  seems  to  be  of  much  less  importance  in  the  formation  of  blood-corpuscles 
(Korn).  All  these  observations  prove  that  the  red  marrow  of  the  bones  is  a  great 
manufactory  for  coloured  blood-corpuscles. 

v.  Recklinghausen  observed  the  direct  transformation  of  these  intermediate 
forms  into  blood-corpuscles  in  frog's  blood,  which  was  kept  for  several  days  in  a 
moist  chamber,  A.  Schmidt  and  Semmer  found  large  lymph  cells  in  the  blood, 
filled  with  granules  of  hsemogoblin,  and  they  regard  these  as  intermediate  forms 
between  colourless  and  coloured  corpuscles. 

[Malassez,  from  an  investigation  of  the  red  marrow  of  young  kids, 
finds  that  the  cells  of  the  red  marrow  and  certain  cells  in  the  spleen 
form  rounded  coloured  projections  or  buds  on  their  surface.  These 
get  detached  and  form  young  blood-corpuscles,  which  soon  become 
disc-shaped;  while  the  mother-cell  itself  continues  to  produce  other 
coloured  corpuscles.  Thus  gemmation  of  the  splenic  and  medullary  cells 
constitutes  one  great  process  in  the  manufacture  of  blood-corpuscles. 
Hence  it  is  apparent  why  diseases  of  bone  in  children  lead  to  aneemia, 
and  soon  bring  about  a  cachectic  condition.] 

8.  Decay  of  tlie  Red  Blood-Corpuscles. 

The  blood-corpuscles  must  positively  undergo  decay  within  a  limited 
time,  and  the  liver  is  regarded  as  one  of  the  chief  places  in  which 
their  disintegration  occurs,  because  bile-pigments  are  formed  from 
haemoglobin,  and  the  blood  of  the  hepatic  vein  contains  fewer  red 
corpuscles  than  the  blood  of  the  portal  vein. 

The  splenic  pulp  contains  cells  which  seem  to  indicate  that  coloured 
corpuscles  are  broken  up  within  it.  These  are  the  so-called  "blood- 
corpuscle-containing  cells."  Quincke's  observations  go  to  show  that  the 
red  corpuscles — which  may  live  from  three  to  four  weeks — when  about 
to  disintegrate,  are  taken  up  by  white  blood-corpuscles,  and  by  the  cells 
of  the  spleen  and  the  bone-marrow,  and  are  stored  up  chiefly  in  the 
spleen  and  marrow  of  bone.  They  are  transformed,  partly  into 
coloured,  and  partly  into  colourless  proteids  which  contain  iron,  and 
are  either  deposited  in  a  granular  form,  or  are  dissolved.  Part  of  the 
products  of  decomposition  is  used  for  the  formation  of  new  blood- 
corpuscles  in  the  marrow  and  in  the  spleen,  and  also  perhaps  in  the 
liver,  while  a  portion  of  the  iron  is  excreted  by  the  liver  in  the  bile. 

That  the  normal  red  blood-corpuscles  and  other  particles  suspended  in  the  blood- 
stream are  not  taken  up  in  this  way,  may  be  due  to  their  being  smooth  and  polished. 


THE   COLOURLESS   BLOOD-CORPUSCLES.  17 

As  the  corpuscles  grow  older  and  become  more  rigid,  they,  as  it  were,  are  caught 
by  the  amceboid  cells.  As  cells  containing  blood-corpuscles  are  very  rarely  found 
in  the  general  circulation,  one  may  assume  that  the  occurrence  of  these  cells  within 
the  spleen,  liver,  and  marrow  of  bone  is  favoured  by  the  slowness  of  the  circulation 
in  these  organs  (Quincke). 

Pathological-  —  In  certain  pathological  conditions,  ferruginous  substances 
derived  from  the  red  blood-corpuscles  ai'e  found  in  the  spleen,  in  the  marrow  of 
bone,  and  in  the  capillaries  of  the  liver  : — (1.)  When  the  disintegration  of  blood- 
corpuscles  is  increased,  as  in  ansemia  (Stahel).  (2.)  When  the  formation  of  red 
blood-corpuscles  from  the  old  material  is  diminished.  If  the  excretion  from  the 
liver  cells  be  prevented,  iron  accumulates  within  them ;  it  is  also  moi-e  abundant  in 
the  blood-serum,  and  it  may  even  accumulate  in  the  secretory  cells  of  the  cortex  of 
the  kidney  and  pancreas,  in  gland  cells,  and  in  the  tissue  elements  of  other  organs 
(Quincke).  When  the  amount  of  blood  is  greatly  increased  (in  dogs),  after  four 
weeks  an  enormous  number  of  granules  containing  iron  occur  in  the  leucocytes  of 
the  liver  capillaries,  the  cells  of  the  spleen,  bone-marrow,  lymph-glands,  the  liver 
cells,  and  the  epithelium  of  the  cortex  of  the  kidney  (Quincke).  The  iron  reaction 
in  the  two  last  situations  occurs  after  the  introduction  of  haemoglobin,  or  of  salts 
of  iron  into  the  blood  (Glaeveck  and  v.  Stark). 

When  we  reflect  how  rapidly  (relatively)  large  quantities  of  blood 
are  replaced  after  haemorrhage  and  after  menstruation,  it  is  evident 
that  there  must  be  a  brisk  manufactory  somewhere.  As  to  the  number 
of  corpuscles  which  daily  decay,  we  have  in  some  measure  an  index 
in  the  amount  of  bile-pigment  and  urine-pigment  resulting  from  the 
transformation  of  the  liberated  haemoglobin. 

9.  The  Colourless  Corpuscles  (Leucocytes). 

Blood,  like  many  other  tissues,  contains  a  number  of  cells  or  cor- 
puscles which  reach  it  from  without;  the  corpuscles  vary  somewhat 
in  form,  and  are  called  colourless  or  tohiie  hlood-corpusdes,  or  "  leucocytes  " 
(Hewson,  1770).  Similar  corpuscles  are  found  in  lymph,  adenoid 
tissue,  marrow  of  bone,  as  wandering  cells  or  leucocytes,  in  connective 
tissue,  ami  also  between  glandular  and  epithelial  cells.  They  all  con- 
sist of  more  or  less  spherical  masses  of  protoplasm,  which  is  sticky, 
highly  refractile,  soft,  capable  of  movement,  and  devoid  of  an  envelope 
(Fig.  6).  When  they  are  quite  fresh  (A)  it  is  difficult  to  detect  the 
nucleus,  but  after  they  have  been  shed  for  some  time,  or  after  the 
addition  of  Avater  (B),  or  acetic  acid,  the  nucleus  (which  is  usually 
a  compound  one)  appears ;  acetic  acid  clears  up  the  perinuclear  proto- 
plasm, and  reveals  the  presence  of  the  nuclei,  of  which  the  number 
varies  from  one  to  four,  although  generally  three  are  found.  The 
subsequent  addition  of  magenta  solution  stains  the  nuclei  deeply. 
Water  makes  the  contents  more  turbid,  and  causes  the  cor- 
puscles to  swell  up.  One  or  more  nucleoli  may  be  present  in  the 
nucleus.  The  corpuscles  contain  proteids,  but  they  also  contain  fats, 
lecithin,  and  salts  (p.  37).     The  size  of  the  corpuscles  varies  from  four 

2 


18 


THE  COLOURLESS  BLOOD-CORPUSCLES. 


^"    5 


li      ^     7 


to  thirteen  /x,  and  as  a  rule  they  are  about  2^  of  an  inch  in  diameter, 

and    in    the    smallest 
"  the  layer  of  the  pro- 

toplasm is  extremely 
thin.  They  all  have 
the  property  of  ex- 
hibiting amoeboid 
movements  which  are 
very  apparent  in  the 
larger  corpuscles. 
These  movements  were 
discovered  by  Wharton 
Jones  in  the  skate,  and 
by  Davine  in  the  cor- 
puscles of  man.  Max 
Schultze  describes 
three  different  forms 
in  human  blood  : — 

Fig.  6. 

(1.)    The    smallest. 

White  blood-corpuscles-A,  Human,  without  the  addi-  ^^^^^^  ^  j^^^  ^^^^ 

tion  of  any  reagent.      B,   after  the  addition  of 

water,  nuclei  visible.    C,  after  the  action  of  acetic  ^^^  ^ed  corpuscles,  With 

acid.      D,  Frog's  corpuscles  showing  changes  of  one  to  tAVO  nuclei,  and 

shape  due  to  amoeboid  movement.     E,  Fibrils  of  ^  ygj.y  gniall  amount  of 

fibrin  from  coagulated    blood.       F,   Elementary  , 

1  protoplasm . 

granules.  r         i.  1 

(2.)  Round  forms, 
the  same  size  as  the  coloured  blood-corpuscles  ; 

(3.)  The  large  amoeboid  corpuscles,  with  much  protoplasm  and 
distinctly  evident  movements, 

[When  a  drop  of  human  blood  is  examined  under  the  microscope, 
i'^fere  especially  after  the  coloured  blood-corpuscles  have  run  into 
rouleaux,  the  colourless  corpuscles  may  readily  be  detected,  there 
being  usually  three  or  four  of  them  visible  in  the  field  at  once. 
They  adhere  to  the  glass  slide,  for  if  the  cover-glass  be  moved,  the 
coloured  corpuscles  readily  glide  over  each  other,  while  the  colourless 
can  be  seen  still  adhering  to  the  slide. 

White  Corpuscles  of  Newt's  Blood. — The  characters  of  the  colourless 
corpuscles  are  best  studied  in  a  drop  of  newt's  blood.  Cut  off  the  tip 
of  the  tail  and  express  a  drop  of  blood  on  to  a  slide,  cover  it  with  a 
thin  glass,  and  examine. 

Neglecting  the  coloured  corpuscles,  search  for  the  colourless,  of  which 
there  are  three  varieties  : — 

(1.)  The  Large  Finely  Granular  Corpuscle,  which  is  about  ydtt  of  an 


THE   COLOURLESS   BLOOD-CORPUSCLES.  19 

inch  in  diameter,  irregular  in  outline,  with  fine  processes  or  pseudo- 
podia,  projecting  from  its  surface.  It  rapidly  changes  its  shape  at  the 
ordinary  temperature,  and  in  its  interior  a  bi-  or  tri-partite  nucleus 
may  be  seen,  surrounded  with  fine  granular  protoplasm,  whose  outline 
is  continually  changing.  Sometimes  vacuoles  are  seen  in  the  proto- 
plasm. 

(2.)  The  Coarsely  Granular  Variety  is  less  common  than  the  first- 
mentioned,  but  when  detected  its  characters  are  distinct.  The  proto- 
plasm contains,  besides  a  nucleus,  a  large  number  of  highly  refractive 
granules,  and  the  corpuscle  usually  exliibits  active  amoeboid  movements ; 
suddenly  the  granules  may  be  seen  to  rush  from  one  side  of  the 
corpuscle  to  the  other.  The  processes  are  usually  more  blunt  than 
those  emitted  by  (1).  The  relation  between  these  two  kinds  of 
corpuscles  has  not  been  ascertained. 

(3.)  The  Small  Colourless  Corpuscles  are  more  like  the  ordinary 
human  colourless  corpuscle,  and  they,  too,  exhibit  amoeboid  move- 
ments. 

Two  kinds  of  colourless  corpuscles  like  (1.)  and  (2.)  exist  in  frog's 
blood.  In  the  coarsely  granular  corpuscles  the  glancing  granules  may 
be  of  a  fatty  nature,  since  they  dissolve  in  alcohol  and  ether,  but  other 
granules  exist  which  are  insoluble  in  these  fluids,  and  the  nature  of 
which  is  unknown.  Very  large  colourless  corpuscles  exist  in  the 
axolotl's  blood  (Kanvier). 

Action  of  Reagents. — (a.)  TFater,  when  added  slowly,  causes  the 
colourless  corpuscles  to  become  globular,  and  the  granules  within  them 
to  exhibit  Brownian  movements  (Eichardson,  Strieker),  (h.)  Pigments, 
such  as  magenta  or  carmine,  stain  the  nuclei  very  deeply,  and  the 
protoplasm  to  a  less  extent,  (c.)  Dilute  Acetic  Acid  clears  up  the 
surrounding  protoplasm  and  brings  clearly  into  view  the  composite 
nucleus,  which  may  be  stained  thereafter  with  magenta,  (d.)  Iodine 
gives  a  faint  port-wine  colour  (horse's  blood  indicating  the  presence  of 
glycogen  best),  (e.)  Dilute  Alcohol  causes  the  formation  of  clear  blebs 
on  the  surface  of  the  corpuscles,  and  brings  the  nuclei  clearly  into  view 
(Eanvier,  Stirling).] 

[A  delicate  plexus  of  fibrils — intra-nuclear  plexus — exists  within  the 
nucleus  just  as  in  other  cells.  It  is  very  probable  that  the  protoplasm 
itself  is  pervaded  by  a  similar  plexus  of  fibrils,  and  that  it  is  continuous 
with  the  intra-nuclear  plexus.] 

The  colourless  corpuscles  divide,  and  in  this  way  reproduce  them- 
selves (Klein). 

The  Number  of  Colourless  Blood-Corpuscles  is  very  much  less  than 
that  of  the  red  corpuscles,  and  is  subject  to  considerable  variations. 

It  is  certain  that  the  colourless  corpuscles  are  very  much  fewer  in 


20         AMOEBOID  MOVEMENTS   OF  THE   COLOURLESS   COEPUSCLES. 


shed  blood  than  in  blood  still  within  the  circulation.  Immediately 
after  blood  is  shed,  an  enormous  number  of  white  corpuscles  disappear 
(see  Formation  of  Fibrin,  p.  47). 

Al.  Schmidt  estimates  tlie  number  that  remain  at  jV  of  the  whole  originally 
present  in  the  circulating  blood.  The  proportion  is  greater  in  children  than  in 
adults  (Bouchut  and  Dubrisay). 

The  following  table  gives  the  number  in  shed  blood  : — 


Number  of  White  Corpuscles  in  Proportion  to  Eed  Corpuscles- 


In  Noi-mal  Conditions. 


In  Different  Places. 


In  Different  Conditions. 


1  :  335  (Welcker). 
1  :  357  (Moleschott). 


Splenic  Vein,      1 :  60 
Splenic  Artery,  1  :  2,260 
Hepatic  Vein,    1  :  170 
Portal  Vein,       1  :  740 
Generally  more  numerous 
in  Veins  than  Arteries. 


Increased  by 
Digestion,  Loss  of  Blood, 
Prolonged  Suppuration, 
Parturition,  Leuksemia, 
Quinine,  Bitters. 
Diminished  by 
Hunger,  Bad  Nourishment. 


The  old  method  of  Welcker  for  estimating  the  number  of  colourless  corpuscles  is 
unsatisfactory.  The  blood  was  defibrinated,  placed  in  a  tall  vessel,  and  allowed  to 
subside,  when  a  layer  of  colourless  corpuscles  was  obtained  immediately  under 
a  layer  of  serum.  [It  is  better  to  use  the  hsemocytometer  (p.  6)  as  improved  by 
Gowers.] 

The  Amoeboid  Movements  of  the  white  corpuscles  (so-called  because 
they  resemble  the  movements  of  amoeba)  consist  in  an  alternate  con- 
traction and  relaxation  of  the  protoplasm  surrounding  the  nucleus. 
Processes  are  given  off  from  the  surface,  and  are  retracted  again  (like 
the  pseudopodia  of  amoeba). 

There  is  an  internal  current  in  the  protoplasm,  and  the  nucleus  has 
also  been  observed  to  change  its  form  (Lavdowsky).  Two  series  of 
phenomena  result  from  these  movements: — (1.)  The  '^wandering"  or 
locomotion  of  the  corjDuscles  due  to  the  extension  and  retraction  of 
their  processes  ;  (2.)  the  ahorjjtion  of  small  particles  into  their  interior 
(fat,  pigment,  foreign  bodies).  The  particles  adhere  to  the  sticky 
external  surface,  are  carried  into  the  interior  by  the  internal  currents 
(Preyer),  and  may  eventually  be  excreted,  just  as  particles  are 
taken  up  by  amoeba  and  the  effete  particles  excreted.  [Max  Schultze 
observed  that  coloured  particles  were  readily  taken  up  by  these 
corpuscles.] 

On  a  hot  stage  (35°-40^C.)  the  colourless  corpuscles  of  mammals 
retain  their  movements  for  a  long  time ;  at  40°C.  for  two  to  three  hours; 
at  50°C.  the  proteids  are  coagulated  and  cause  "heat-rigor"  and  death. 
In  cold-blooded  animals  (frogs)  colourless  corpuscles  may  be  seen  to  crawl 


THE  BLOOD-PLATES. 


21 


out  of  small  coagula,  in  a  moist  chamber,  and  move  about  in  the 
serum.  Indiidion  shocks  cause  them  to  withdraw  their  processes  and 
become  spherical,  and,  if  the  shocks  be  not  too  severe,  their  movements 
recommence.  Strong  shocks  kill  them.  0  is  necessary  for  their 
movements.  These  amoeboid  movements  are  of  special  interest  on 
account  of  the  "  wandering  out "  (diapedesis)  of  colourless  blood- 
corpuscles  through  the  walls  of  the  blood-vessels  (Waller,  Cohnheim). 

The  chyle  contains  leucocytes,  which  are  more  resistant  than  those  of  the  blood, 
but  less  so  than  those  of  the  coagulable  transudations  (Heyl).  The  leucocytes 
of  the  lymphatic  glands  may  also  be  dissolved  (Rauschenbach). 

Relation  to  Aniline  Pigments.— Ehrlich  has  observed  a  remarkable  relation 
of  the  white  corpuscles  to  acid  (eosin,  picric  acid,  aurantia),  basic  (dahlia,  acetate 
of  rosanilin),  or  neutral  (picrate  of  rosanilin)  reactions.  The  smallest  protoplasmic 
granules  of  the  cells  have  different  chemical  affinities  for  these  pigments.  Thus 
Ehrlich  distinguishes  "eosinophile,"  "basophile,"  and  "  neutrophile "  granules 
within  the  cells.  Eosinophile  granules  occur  in  the  leucocytes  of  amphibia,  and 
in  the  marrow  of  their  bones.  Human  leucocytes  exhibit  a  neutrophile  reaction, 
except  in  the  case  of  those  corpuscles  that  have  large  ovoid  nuclei :  the  former 
are  said  to  be  the  early  stage  of  the  latter.  The  eosinophile  corpuscles  are  greatly 
increased  in  leukaemia.  The  basophile  granules  occur  chiefly  in  connective  tissue- 
corpuscles  and  in  the  neighbourhood  of  epithelium — they  are  always  greatly 
increased  where  chronic  inflammation  occurs. 

III.  Special  attention  has  recently  been  directed  to  a  ihircl  element 


5 


i    a 


^     0 


Fig.  7. 

"Blood-plates"  and  their  derivatives,  partly  after  Bizzozero  and  Laker.  1,  Red 
blood-corpuscles  on  the  flat.  2,  From  the  side.  3,  Unchanged  blood-plates. 
4,  A  lymph-corpuscle,  surrounded  with  blood-plates.  5,  Blood-plates 
variously  altered.  6,  A  lymph-corpuscle  with  two  heaps  of  fused  blood- 
plates  and  threads  of  fibrin.  7,  Group  of  blood-plates  fused  or  run  together. 
8,  A  similar  small  heap  of  partially  dissolved  blood-plates  with  fibrils  of  fibrin. 


'22  CHANGES    OF   THE   RED    AND   WHITE  BLOOD-CORPUSCLES. 

of  the  blood,  the  "  blood-plates  "  of  Bizzozero ;  pale,  colourless,  biconcave 

discs  of  variable  size  (mean,  3  fx).     According  to  Hay  em  (who  called 

these  structures  hl^matoblasts,  supposing  that  they  were  an  early 

stage  in  the  development  of  the  red  blood-corpuscles),  they  are  forty 

times  as  numerous  as  the  leucocytes.       These   blood-plates  may  be 

recognised  in  circulating  blood,  as  in  the  mesentery  of  the  guinea-pig. 

They  are  precipitated  in  enormous  numbers  upon  threads  suspended  in 

fresh-shed   blood   (Bizzozero).      They   may   be   obtained   from  blood 

flowing  directly  from  a  blood-vessel,  on  mixing  it  with  1  per  cent. 

solution  of  osmic  acid  or  Hayem's  fluid  (mercury  bichloride  0*5,  sodium 

carbonate  5,  sodium  chlorate  1,  distilled  water  200 — ^Laker).     They 

undergo  a  rapid  change   in   shed  blood   (Fig.   7,   5),   disintegrating, 

forming  small  particles,  and  ultimately  dissolving.    When  several  occur 

together  they  rapidly  unite,  form  small  groups  (7),  and  collect  into 

masses  resembling  "  stroma-fibrin "   (p.    48).      These  masses  may  be 

associated  in  coagulated  blood  with  fibrils  of  fibrin. 

Bizzozero  believes  that  they  yield  the  material  for  the  formation  of  fibrin  during 
coagulation  of  the  hlood.  It  is  not  yet  determined  whether  they  are  derived  from 
partially  disintegrated  leucocytes,  or  whether  they  are  independent  formations. 
Along  with  the  leucocytes  they  are  concerned  in  the  formation  of  fibrin  (Hlava). 
These  structures  were  known  to  earlier  observers  (Max  Schultze,  Riess,  and 
others) ;  but  their  significance  has  been  variously  interj)reted, 

IV.  Blood,  especially  after  a  microscopic  preparation  has  been  made 
for  a  short  time,  is  seen  to  contain  elementary  granules  (Fig.  6,  F), 
[i.e.,  the  elementary  particles  of  Zimmermann  and  Beale.  They  are 
irregular  bodies,  much  smaller  than  the  ordinary  corpuscles,  and  appear 
to  consist  of  masses  of  protoplasm  detached  from  the  surface  of 
leucocytes,  or  derived  from  the  disintegration  of  these  corpuscles,  or 
of  the  blood-plates.  Others,  again,  are  completely  spherical  granules, 
either  consisting  of  some  proteid  substance  or  fatty  in  their  nature. 
The  protoplasmic  and  the  proteid  granules  disappear  on  the  addition 
of  acetic  acid,  while  the  fatty  granules  (which  are  most  numerous  after  a 
diet  rich  in  fats)  dissolve  in  ether]. 

V,  In  coagulated  blood,  deHcate  fibrils  or  threads  of  fibrin  (Fig. 
6,  E  and  6,  8,  G)  are  seen,  more  especially  after  the  corpuscles  have 
run  into  rouleaux.  At  the  nodes  of  these  fibres  are  found  granules 
which  closely  resemble  those  described  under  III. 

[These  granules  and  fibres  are  stained  by  magenta  and  iodine,  bvit 
not  by  carmine  or  picro-carmine  (Ranvier).] 

10.  Abnormal  Changes  of  the  Red  and  White 
Blood-Corpuscles. 

{!•)  All  haemorrhages  diminish  the  number  of  red  corpuscles  (at  most  one- 
half  J,  and  so  does  menstruatiov.     The  loss  is  partly  covered  by  the  absorption  of 


CHANGES   OF   THE   RED   AND   WHITE   BLOOD-CORPUSCLES.  23 

fluid  from  the  tissues.  Menstruation  shows  us  that  a  moderate  loss  of  red  cor- 
puscles is  replaced  within  twenty-eight  days.  When  a  large  amount  of  blood  is 
lost,  so  that  all  the  vital  processes  are  lowered,  the  time  may  be  extended  to  five 
weeks.  In  acute  fevers,  as  the  temperature  increases,  the  number  of  red  corpuscles 
diminished,  while  the  wJiite  corpuscles  increase  in  number  (Riegel  &  Boeckmann). 

(2.)  Diminished  production  of  new  red  corpuscles  causes  a  decrease,  since 
blood-corpuscles  are  continually  being  used  up.  In  chlorotic  girls  there  seems  to 
be  a  congenital  wealmess  in  the  blood-foi-ming  and  blood-propelling  apparatus,  the 
cause  of  which  is  to  be  sought  for  in  some  faulty  condition  of  the  meso-blast.  In 
them  the  heart  and  the  blood-vessels  are  small,  and  the  absolute  number  of  cor- 
puscles may  be  diminished  one-half,  although  the  relative  number  may  be  retained, 
while  in  the  corpuscles  themselves  the  hiemoglobin  is  diminislied  almost  one-third 
(Duncan,  Quincke)  ;  but  it  rises  again  after  the  administration  of  iron  (Haj'em). 
The  administration  of  iron  increases  the  amount  of  haemoglobin  in  the  blood 
(Scherpf).  The  amount  of  iron  in  the  blood  maybe  diminished  one-half.  [The 
action  of  iron  in  anamic  persons  has  been  known  since  the  time  of  Sydenham. 
Hayem  also  finds  that  in  certain  forms  of  anemia  there  is  considerable  variation 
in  the  size  of  the  red  corpuscles,  and  that  in  chronic  anaemia  the  mean  diameter 
of  the  corpuscles  is  always  less  than  normal  (7  M  to  6  m)-  There  is,  moreover,  a 
persistent  alteration  in  the  volume,  colouring  j^oiuer,  and  consistence  of  the  cor- 
puscles, consequently  a  want  of  accord  between  the  number  of  the  corpuscles  and 
their  colouring  power — i.e.,  the  amount  of  haemoglobin  which  they  contain,  as  was 
pointed  out  by  Johann  Duncan.]  In  so-called  jiernicious  ancemia,  in  which  the 
continued  decrease  in  the  red  corpuscles  may  ultimately  produce  death,  there  is 
undoubtedly  a  severe  affection  of  the  blood-forming  apparatus.  The  corpuscles 
assume  many  abnormal  and  bizarre  forms  (microcytes),  often  being  oval  or  tailed, 
irregularly  shaped,  and  sometimes  very  pale ;  while  numerous  cells  containing 
blood-corpuscles  are  found  in  the  marrow  of  bone  (Riess).  Curiously  enough  in 
this  disease,  although  the  red  blood-corpuscles  are  diminished  in  number,  some 
may  be  larger  and  contain  more  haemoglobin  than  do  normal  corpuscles  (Laache). 
The  number  of  coloured  corpuscles  is  also  diminished  in  chronic  poisoning  by  lead 
or  miasmata,  and  also  by  the  poison  of  syphilis. 

(3.)  Abnormal  forms  of  the  red  corpuscles  have  been  observed  after  severe 
burns  (Lesser) ;  the  corpuscles  are  much  smaller,  and  under  the  influence  of  the 
heat,  particles  seem  to  be  detached  from  them  just  as  can  be  seen  happening  under 
the  microscope  as  the  effect  of  heat  (Wertheim).  Disintegration  of  the  corpuscles 
into  fine  droplets  has  been  observed  in  various  diseases,  as  in  severe  malarial 
fevers.  The  dark  granules  of  a  pigment  closely  related  to  hsematin  are  derived  from 
the  granules  arising  from  the  disintegration  of  the  blood-corpuscles,  and  these 
particles  float  in  the  blood  (Jlelancemia).  They  are  partly  absorbed  by  the  colour- 
less corpuscles,  but  they  are  also  deposited  in  the  spleen,  liver,  brain,  and  bone- 
marrow  (Arnstein).  Sometimes  the  red  corpuscles  are  abnormally  soft,  and 
readily  yield  to  pressure. 

The  white  corpuscles  are  enormously  increased  in  number  in  Leukcemia 
(J.  H.  Bennett  and  Vnchovv) ;  sometimes  even  to  the  extent  of  the  red  corpuscles. 
In  some  cases  the  blood  looks  as  if  it  were  mixed  with  milk.  The  colourless  cor- 
puscles seem  to  be  formed  chiefly  in  bone-marrow  (Neumann),  but  also  in  the 
spleen  and  Ij'mphatic  glands. 

11.  Chemical  Constituents  of  the  Red 
Blood-Corpuscles. 

(1.)  The  colouring-matter  or  haemoglohin  (Hb)  (Ha^mato-globulin, 
Hsemato-crystallin)  is  the  cause  of  the  red  colour  of  blood  ;  it  also  occurs 


24 


PREPARATION   OF  HEMOGLOBIN   CRYSTALS. 


in  muscle,  and  in  traces  in  the  fluid  part  of  blood,  but  in  this  last  case 
only  as  the  result  of  the  solution  of  some  red  corpuscles.  Its  per- 
centage coraposition  is: — C  53-85,  H  7-32,  N  16-17,  Fe  0-42,  S  0-39, 
0  21-84  (dog).  Its  rational  formula  is  unknown,  but  Preyer  gives 
the  empirical  formula  CggQ,  HggQ,  Nj^^,  Fe,  Sg,  Oi^g.  Although  it  is  a 
colloid  substance  it  crystallises  (Hiinefeld  1840,  Reichert)  in  all  classes 
of  vertebrates,  according  to  the  rhombic  system,  and  chiefly  in  rhombic 
plates  or  prisms ;  in  the  guinea-pig  in  rhombic  tetrahedra  (v.  Lang)  ; 
in  the  squirrel,  however,  it  yields  hexagonal  plates.  The  varying 
forms,  perhaps,  correspond  to  slight  diff'erences  in  the  chemical  com- 
position in  different  cases. 

Crystals  separate  from  the  blood  of  ail  classes  of  vertebrata  during 
the  slow  evaporation  of  lake-coloured  blood,  but  with  varying  facility. 

The  coloiiring-matter  crystallises  very  readily  from  the  blood  of  man,  dog, 
mouse,  guinea-pig,  rat,  cat,  hedgehog,  horse,  rabbit,  birds,  fishes  ;  with  difficulty 
from  that  of  the  sheep,  ox,  and  pig.  Coloured  crystals  are  not  obtained  from  the 
blood  of  the  frog.  More  rarely  a  crystal  is  formed  from  a  single  corpuscle 
enclosing  the  stroma.  Crystals  have  been  found  near  the  nucleus  of  the  large 
corpuscles  of  fishes,  and  in  this  class  of  vertebrates  colourless  crystals  have  been 
observed. 

Haemoglobin     crystals    are    doubly 

refractive     and    pleo-chromatic ;     they 

are  bluish-red  with  transmitted  light, 

scarlet-red  by  reflected  light.      They 

contain  from  3  to   9  per  cent,  water 

of  crystallisation,   and  are  soluble  in 

water,  but  more  so  in  dilute  alkalies. 

They  are  insoluble  in  alcohol,  ether, 

chloroform,  and  fats.      The  solutions 

are  dichroic;   red  in    reflected    light, 

and  green  in  transmitted  light. 


; 


In  the  act  of  crystallisation  the  hajmoglobin 

seems   to    undergo   some    internal    change. 

Before  it  crystallises  it  does  not  diffuse  like 

a  true  colloid,  and  it  also  rapidly  decomposes 

Fio-.  8.  hydric  peroxide.     If  it  be  redissolved  after 

Haemoglobin  cr/stals-a,  b,   from   crystallisation  it  diffiises,   although  only  to 

human  blood  ;  c,  from  the  cat ;    t  ''"^"  '''*'''>  b^^^^.^'^^^^^f  ^  deconiposes 
,      o    _     . ,  .  .  hydric  peroxide,  and  is  decolourised   by  it. 

d,    from    the    gumea-pig;     e,     /,     ,  ^,.,  •  ■■  ■    •,        -4.  j  ^        i, 

A  body  like  an  acid  is  deposited  from  hsemo- 

globin  at  the  positive  pole  of  a  battery. 


hamster;  f,  squirrel. 


12,  Preparation  of  Hsemoglolbin  Crystals. 

Method  of  Eollett.— Place  defibrinated  blood  in  a  platinum  capsule,   allow 
the  capsule  and  the  blood  to  freeze  by  setting  them  in  a  freezing-mixture,  and 


ESTIMATION    OF   HEMOGLOBIN.  25 

then  gradually  to  thaw ;  pour  the  lake-coloured  blood  into  a  plate,  until  it 
forms  a  stratum  not  more  than  Ik  m.m.  in  thickness,  and  allow  it  to  evaporate 
slowly  in  a  cool  place,  when  crystals  will  separate. 

Method  of  Hoppe-Seyler.— ^lix  defibrinated  blood  with  ten  volumes  of  a  20 
per  cent,  salt  solution,  and  allow  it  to  stand  for  two  days.  Remove  the  clear 
upper  fluid  with  a  ])ipette,  wash  the  thick  deposit  of  blood-corpuscles  with 
water,  and  afterwards  shake  it  for  a  long  time  with  an  equal  volume  of  ether, 
which  dissolves  the  blood-corpuscles.  Remove  the  ether,  filter  the  lake-coloured 
blood,  add  to  it  |  of  its  volume  of  cold  (0")  alcohol,  and  allow  the  mixture 
to  stand  in  the  cold  for  several  days.  The  numerous  crystals  can  be  collected  in 
a  filter  and  pressed  between  folds  of  blotting-paper. 

Method  of  Gscheidlen.— Crystals  several  centimetres  in  length  were  obtained 
by  taking  defibrinated  blood  which  had  been  exposed  for  twenty-four  hours  to  the 
air,  and  keeping  it  in  a  closed  tube  of  narrow  calibre  for  several  days  at  37°C. 
When  the  blood  is  spread  on  glass,  the  crystals  form  rapidly.  [Vaccine  tubes 
answer  very  well.] 

[Method  of  Stirling  and  BritO. — It  is  in  many  cases  sufficient  to  mix  a  drop 
of  blood  with  a  few  drops  of  water  on  a  microscopic  slide,  and  to  seal  up  the 
preparation.  After  a  few  days  beautiful  crystals  ai-e  developed.  The  addition  of 
water  to  the  blood  of  some  animals,  such  as  the  rat  and  guinea-pig,  is  rapidlj' 
followed  by  the  formation  of  crystals  of  hemoglobin.  Very  large  crj'stals  may 
be  obtained  from  the  stomach  of  the  leech  several  days  after  it  has  sucked  blood.] 

13.  Quantitative  Estimation  of  Haemoglobin. 

(«.)  From  the  Amount  of  Iron-— As  dry  (100°C.)  haemoglobin  contains  0*42 
per  cent,  of  iron,  the  amount  of  iron  may  be  calculated  from  the  amount  of 
haimoglobin.  If  m  represents  the  percentage  amount  of  metallic  iron,  then  the 
percentage  of  htemoglobin  in  blood  is 

_  100j?j 

~   0*42 

The  procedure  is  the  following : — Calcine  a  weighed  quantity  of  blood,  and  exhaust 
the  ash  with  HCl  to  obtain  ferric  chloride,  which  is  transformed  into  ferrous 
chloride.     The  solution  is  then  titrated  with  potassic  permanganate. 

(b.)  Colorimetric  Method. — Prepare  a  dilute  watery  solution  of  haemoglobin 
crystals  of  a  known  strength.  With  this  compare  an  aqueous  dilution  of  the 
blood  to  be  investigated,  by  adding  water  to  it  until  the  colour  of  the  test 
solution  is  obtained.  Of  course,  the  solutions  must  be  compared  in  vessels  with 
parallel  sides  and  of  exactly  tlie  same  width,  so  as  to  give  the  same  thickness  of 
fluid  (Hoppe-Seyler).  [In  the  vessel  with  parallel  sides,  or,  hcvmaiinometer,  the  sides 
are  exactly  one  centimetre  apart.  Instead  of  using  a  standard  solution  of  oxyhee- 
moglobin,  a  solution  of  picro-carminate  of  ammonia  may  be  used  (Rajewsky, 
Malassez.)  ] 

(c.)  By  the  Spectroscope- — Preyer  found  that  a  0*8  per  cent,  watery  solution 
(1  cm.  thick),  allowed  the  red,  the  yellow,  and  the  first  strip  of  green  to  be  seen 
(Fig.  11,  1).  Take  the  blood  to  be  investigated  (about  O'o  cm.),  and  dilute  it  with 
water  until  it  shows  exactly  the  same  optical  eff"ects  in  the  spectroscope.  If  k  is 
the  percentage  of  Hb,  which  allows  green  to  pass  through  (O'S  per  cent.),  b,  the 
volume  of  blood  investigated  (about  0'5  cm.),  ic,  the  necessary  amount  of  water 
added  to  dilute  it,  then  x  -  the  percentage  of  Hb  in  the  blood  to  be  investi- 
gated— 

k  (lu  +  b) 
^~  b 


26 


THE    HiEMOGLOBINOMETER. 


[  (d. )  The  HSBmOglobinOineter  of  Gowers  is  used  for  tlie  clinical  estimation  of 
lifemoglobin.] 

"The  tint  of  the  dilution  of  a  given  volume  of  blood  with  distilled  water  is 
taken  as  the  index  of  the  amount  of  haemoglobin.  The  distilled  water  rapidly 
dissolves  out  all  the  hasmoglobin,  as  is  shown  by  the  fact  that  the  tint  of  the 
dilution  undergoes  no  change  on  standing.  The  colour  of  a  dilution  of  average 
normal  blood  one  hundred  times  is  taken  as  the  standard.  The  quantity  of 
haemoglobin  is  indicated  by  the  amount  of  distilled  water  needed  to  obtain  the 
tint  with  the  same  volume  of  blood  under  examination  as  was  taken  of  the 
standard.  On  account  of  the  instability  of  a  standard  dilution  of  blood,  tinted 
glycerine -jelly  is  employed  instead.  This  is  perfectly  stable,  and  by  means  of 
carmine  and  picrocarmine  the  exact  tint  of  diluted  blood  can  be  obtained. 

The  apparatus  consists  of  two  glass  tubes  of  exactly  the  same  size.  One  contams 
(D)  a  standard  of  the  tint  of  a  dilution  of  20  cubic  m.m.  of  blood,  in  2  cubic  centi- 
metres of  water  (1  in  100). 

The  second  tube  (C)  is  graduated,  100  degrees  =  two  centimetres  (100  times 
twenty  cubic  millimetres). 

The  twenty  cubic  millimetres  of  blood  are  measured  by  a  capiUary  pipette  (B) 
(similar  to,  but  larger  than  that  used  for  the  haemacytometer).  This  quantity  of 
the  blood  to  be  tested  is  ejected  into  the  bottom  of  the  tube,  a  few  drops  of  distilled 
water  being  first  placed  in  the  latter.  The  mixture  is  rapidly  agitated  to  prevent 
the  coagulation  of  the  blood.  The  distilled  water  is  then  added  drop  by  drop 
(from  the  pipette  stopper  of  a  bottle  [A]  supplied  for  that  purpose)  until  the  tint  of 
the  dilution  is  the  same  as  that  of  the  standard,  and  the  amount  of  water  which  has 
been  added  {i.e.,  the  degree  of  dilution)  indicates  the  amount  of  haemoglobin. 

Since  average  normal  blood  yields  the  tint  of  the  standard  at  100  degrees  of 
dilution,  the  number  of  degrees  of  dilution  necessary  to  obtain  the  same  tint  with 

a  given  specimen  of  blood 
is  the  percentage  propor- 
tion of  the  haemoglobin 
contained  in  it,  compared 
to  the  normal. 

For  instance,  the  20 
cubic  millimetres  of 
blood  from  a  patient 
with  anaemia  gave  the 
standard  tint  at  30 
degrees  of  dilution. 
Hence  it  contained  only 
30  per  cent,  of  the  normal 
quantity  of  haemoglobin. 
By  ascertaining  with  the 
haemacytometer  the  cor- 
puscular richness  of  the 
blood,  we  are  able  to 
compare  the  two.  A 
fraction,  of  which  the 
numerator  is  the  per- 
A,  pipette  bottle  for  distilled  water;  B,  capillary  pipette;  rentage  of  haemoglobm, 
C,  graduated  tube  ;  U,  tube  with  standard  dilution ;  ^nd  the  denommator 
F,  lancet  for  pricking  the  finger.  *^e   percentage   of  cor- 

puscles, gives  at  once 
the  average  value  per  corpuscle.  Thus  the  blood  mentioned  above  containing  30 
per  cent,  of  haemogloljin,  contained  60  per  cent,  of  corpuscles  ;  hence  the  average 


USE   OF  THE   SPECTROSCOPE.  27 

value  of  each  corpuscle  was  ^§  or  ^  of  the  normal.  Variations  in  the  amount  of 
hremoglobin  may  be  recorded  on  the  same  chart  as  that  employed  for  the  corpuscles. 

In  using  the  instrument,  the  tint  may  be  estimated  by  holding  the  tubes  between 
the  eye  and  the  window,  or  by  placing  a  piece  of  white  paper  behind  the  tubes  ; 
the  former  is  perhaps  the  best.  Care  must  be  taken  that  the  tubes  are  always 
held  in  the  line  of  light,  not  below  it.  In  the  latter  case  some  light  is  reflected 
from  the  suspended  corpuscles  from  which  the  hjemoglobin  has  been  dissolved. 
If  the  value  of  the  corpuscles  is  small,  then  a  perceptibly  paler  tint  is  seen  when 
the  tubes  are  held  below  the  line  of  illumination.  If  all  the  light  is  transmitted 
directly  through  the  tubes,  the  corpuscles  do  not  interfere  with  the  tint. 

In  using  the  instrument  it  will  be  found  that,  during  6  or  8  degrees  of  dilution, 
it  is  difficult  to  distinguish  a  difference  between  the  tint  of  the  tubes.  It  is  there- 
fore necessary  to  note  the  degree  at  which  the  colour  of  the  dilution  ceases  to  be 
deeper  than  the  standard,  and  also  that  at  which  it  is  distinctly  paler.  The  degree 
midway  between  these  two  will  represent  the  haemoglobin  percentage. 

The  instrument  is  only  expected  to  yield  approximate  results,  accurate  within 
2  or  3  per  cent.  It  has,  however,  been  found  of  much  utility  in  clinical  observa- 
tion."] 

The  amount  of  haemoglobin  in  man  is  12  to  15  per  cent.,  in  the 
woman  12  to  14  per  cent.,  during  pregnancy  9  to  12  per  cent. 
(Preyer).  According  to  Leichtenstern,  Hb  is  in  greatest  amount  in 
the  blood  of  the  newly-born  infant,  but  after  ten  weeks  the  excess 
disappears.  Between  six  months  and  five  years,  it  becomes  least  in 
amount,  reaches  its  second  highest  maximum  between  twenty-one 
and  forty-five,  and  then  sinks  again.  From  the  tenth  year  onwards 
the  blood  of  the  female  is  poorer  in  Hb.  The  taking  of  food  causes  a 
temporary  decrease  of  the  Hb,  owing  to  the  dilution  of  the  blood. 

PathologicaL — A  decrease  is  observable  during  recovery  from  febrile  condi- 
tions, and  also  during  phthisis,  cancer,  ulcer  of  the  stomach,  cardiac  disease, 
chronic  diseases,  chlorosis,  leukagmia,  pernicious  antemia,  and  during  the  rapid 
mercurial  treatment  of  syphilitic  persons. 


14,  Use  of  the  Spectroscope. 

As  the  spectroscope  is  frequently  used  in  the  investigation  of  blood  and  other 
substances  of  the  body,  it  will  be  convenient  to  give  a  short  description  of  the 
instrument  here  (Fig.  10).  It  consists  of — (1.)  a  tube.  A,  which  has  at  its  peripheral 
end  a  slit,  S  (that  can  be  narrowed  or  widened).  At  the  other  end  a  collecting  lens, 
C  (called  a  collimator)  is  placed,  so  that  its  focus  is  in  exact  line  with  the  slit. 
Light  (from  the  sun  or  a  lamp)  passes  through  the  slit,  and  thus  goes  parallel 
through  C  to — (2.)  the  prism,  P,  which  decomposes  the  parallel  rays  into  a 
coloured  spectrum,  r  -  v. — (3.)  An  astronomical  telescope  is  directed  to  the  spectrum, 
r-v,  and  the  observer,  B,  with  the  aid  of  the  telescope,  sees  the  spectrum  magnified 
from  six  to  eight  times ; — (4.)  a  third  tube,  D,  contains  a  delicate  scale,  M,  on  glass, 
whose  image,  when  illuminated,  is  reflected  from  the  prism  to  the  eye  of  the 
observer,  so  that  he  sees  the  spectrum,  and  over  or  above  it  the  scale.  To  keep 
out  other  rays  of  light  the  inner  ends  of  the  three  tubes  are  covered  by  metal  or 
by  a  dark  cloth  (see  also  Blood  In  urine). 

[The  micro-spectroscope,  e.g.,  that  known  as  the  "  Sorby-Browning "  micro- 
spectroscope  is  very  useful  when  small  quantities  of  a  solution  arc  to  be  exaniined.] 


28 


ABSORPTION   AND    FLAME   SPECTRA. 


[Every  spectroscope  ought  to  give  two  spectra,  so  that  the  position  of  any  absorp- 
tion band  may  be  definitely  ascertained.  The  spectroscope  is  fitted  into  the 
ocular  end  of  the  tube  of  a  microscope  instead  of  the  eye-piece.  Small  cells  for 
containing  the  fluid  to  be  examined  are  made  from  short  pieces  of  barometer-tubes 
cemented  to  a  plate  of  glass.  ] 


Fig.  10. 

Scheme  of  a  spectroscope  for  observing  the  spectrum  of  blood — A,  tube  ;  S,  slit ; 
m  m,  layer  of  blood  with  flame  in  front  of  it ;  P,  prism ;  M,  scale ;  B,  eye  of 
observer  looking  through  a  telescope  ;  r  v,  spectrum. 


Absorption  Spectra. — If  a  coloured  medium  {e.g.,  a  solution  of  blood) 
be  placed  between  the  slit  and  a  source  of  light,  all  the  rays  of  coloured 
light  do  not  pass  through  it — some  are  absorbed  ;  many  yellow  rays  are 
absorbed  by  blood,  hence  that  part  of  the  spectrum  appears  dark  to 
the  observer.  On  account  of  this  absorption,  such  a  spectrum  is  called 
an  "  absorption  siJednmi." 

Flame  Spectra. — If  mineral  substances  be  burned  on  a  platinum- 
wire  in  a  non-luminous  flame  (Bunsen's  burner)  in  front  of  the  slit,  the 
elements  present  in  the  mineral  or  ash  give  special  coloured  band  or 
bands,  which  have  a  definite  position.  Sodium  gives  a  yellow, 
potassium  a  red  and  a  violet  line.  These  substances  are  found  in 
burning  the  ashes  of  almost  all  organs. 

If  sunlight  be  allowed  to  fall  upon  the  slit,  the  spectrum  shows 
a  large  number  of  lines  (Fmunhofers  lines)  which  occupy  definite  posi- 
tions in  the  coloured  spectrum.  These  lines  are  indicated  by  the 
letters  A,  B,  C,  D,  etc.,  a,  b,  c,  etc.  (Fig.  11), 


COMPOUNDS   OF   HAEMOGLOBIN, 


29 


16»  Compounds  of  Hsemoglobin  with  0 ;  Oxyhsemoglobin, 
and  Methsemoglobin. 

(1.)  Oxyhaemoglobin  (0„H^j)  behaves  as  a  weak  acid,  and  occurs  to 
the  extent  of  86-78  to  94:"30  per  cent,  in  dry  red  human  corpuscles 
(Jiidell).  It  is  formed  very  readily  whenever  Hb  comes  into 
contact  with  0  or  atmospheric  air.  1  gramme  Hb  unites  with 
1-6  to  rs  cubic  centimetres  of  0  at  0°  and  760  mm.  Hg  pressure. 
Oxyhsemoglobin  is  a  very  loose  chemical  com-pound,  and  is  slightly  less 
soluble  than  Hb ;  its  spectrum  shows  in  the  yellow  and  the  green,  two 
(lark  ahsorption-bands  (Hoppe-Seyler)  whose  length  and  breadth  in  a 
0"18  per  cent,  solution  are  given  in  Fig.  11  (2). 


Red.     Orange. 


Yellow. 


Green. 


Blue. 


I  Mill  llimi  llll  illlLilil,-!  Mil  LIMLI  III  l|l|  I  I  I  II  111  llh  I  111  l^ljlLTn 
40  Bo  6o  70  80  ()o  loo  110 


A     a      B     C  D  F  F 

Fig.  11. 

Various  spectra  of  hjemoglobin  and  its  compounds. 


Bamoglobin 
0.8  V, 


0  = 
Hanio;;Iobin 


Cfl  rbonic 

Oxide 

Hamofflobin. 


Hamatin  in 

an  Alkaline 

Solution. 


Rednced 
Hamatin. 


30  REDUCTION    OF  HEMOGLOBIN. 

[The  two  absorption-bands  lie  between  the  lines  D  and  E,  the  band 
nearer  D  being  more  sharply  defined  and  narrower  than  the  second 
band,  which  is  wider  and  less  clearly  marked-off,  and  lies  nearer  E.] 

It  occurs  in  the  blood-corpuscles,  circulating  in  arteries  and  capillaries, 
as  was  shown  by  the  spectroscopic  examination  of  the  ear  of  a  rabbit,  of 
the  prepuce  and  the  web  of  the  fingers  (Vierordt). 

Reduction  of  Oxyhsemoglobin. — It  gives  up  its  0  very  readily,  how- 
ever, even  when  means  which  set  free  absorbed  gases  are  used.  It  is 
reduced  by  the  removal  of  the  gases  by  the  air-pump,  by  the  conduction 
through  its  solution  of  other  gases  (CO  &  NO),  and  by  heating  to  the 
boiling  point.  In  the  circulating  blood  its  0  is  very  rapidly  given  up 
to  the  tissues,  so  that  in  suffocated  animals  only  reduced  hcemoghhin 
is  found  in  the  arteries.  Some  constituents  of  the  serum  and  sugar 
use  up  0.  By  adding  to  a  solution  of  oxyhsemoglobin  reducing  sub- 
stances— e.g.,  ammonium  sulphide,  ammoniated  tartarate  of  zinc  oxide 
solution,  iron  filings,  or  Stokes's  fluid  [tartaric  acid,  iron  proto-sulphate, 
and  excess  of  ammonia] — the  two  absorption  bands  of  the  spectrum  dis- 
appear, and  reduced  hcemoglohin  (gas-free)  (Fig.  11,  4),  with  one  absorp- 
tion band  is  formed  (Stokes,  1864).  [The  single  band  which  is  obtained 
from  reduced  haemoglobin  lies  between  D  and  E,  and  its  most  deeply 
shaded  portion  is  opposite  the  interval  between  the  two  bands  of  oxy- 
hsemoglobin.  Its  edges  are  less  sharply  defined.  The  colour  of  the 
blood  changes  from  a  bright  red  to  a  brownish  tint.  Hoppe-Seyler 
applies  the  term  Hcemoglohin  to  the  reduced  substance  to  distinguish  it 
from  oxyhsemoglobin.] 

The  two  bands  are  reproduced  by  shaking  the  reduced  haemoglobin 
with  air,  whereby  OgHb  is  again  formed.  Solutions  of  oxyhsemoglobin 
are  readily  distinguished  by  their  scarlet  colour  from  the  purplish  tint 
of  reduced  haemoglobin. 

If  a  string  be  tied  round  the  base  of  two  fingers  so  as  to  interrupt  the  circulation, 
the  spectroscopic  examination  shows  that  the  oxyhfemoglobin  rapidly  passes  into 
reduced  Hb  (Vierordt) .     Cold  delays  this  reduction  (Filehne). 

The  spectroscopic  examination  of  small  blood-stains  is  often  of  the  utmost 
forensic  importance.  A  minimal  drop  is  sufficient.  Dissolve  in  a  few  drops  of 
distilled  water,  and  place  in  a  thin  glass  tube  in  front  of  the  slit  of  the  spectroscope. 

(2.)  Methsemoglobin    (Hoppe-Seyler)  contains   more   0   than   oxy- 

haemoglobin  (Fig.  11,  5).    Chemically  it  is  fairly  stable,  contains  0,  and 

crystallises  (Hiifner  and  J.  Ott).     It  is   obtained  by  acting  upon  a 

solution  of  reduced  or  oxyhaemoglobin  with  oxidising  reagents ;  best, 

however,  by  adding  crystals  of  potassic  ferridcyauide.     It  shows  four 

absorption  bands  like  an  acid  solution  of  haematin,  that  between  C  and 

D  being  the  only  one  sharply  defined. 

If  a  trace  of  ammonia  be  added  to  such  a  solution,  it  gives  an  alkaline  solution 
of  methsemoglobin,  which  shows  two  bands  like  oxyhaemoglobin,  of  which  the  first 


CARBONIC   OXIDE-HiflMOGLOBIN,  31 

one  is  the  broader,  and  extends  more  into  the  red.  If  ammonium  sulphide  be 
added  to  the  methaemoglobin  solution,  reduced  Hb  is  formed  (Jaderholm).  Methse- 
raoglobin  is  produced  in  old  brown  blood-stains,  in  the  crusts  of  bloody  wounds,  in 
blood  cysts — farther  by  the  addition  of  minute  traces  of  acid  to  blood,  or  by 
heating  blood  with  a  trace  of  alkali.  Sorby  and  Jaderholm  regard  it  as  a  per- 
oxidised  haemoglobin,  but  this  view  is  opposed  by  Hoppe-Seyler.  It  may  also 
be  prepared  by  acting  upon  blood  with  potassic  chlorate  and  nitrate,  or  nitrate  of 
amyl,  which  gives  to  blood  a  chocolate-brown  colour  (Saarbach,  Gamgee). 

16.  Carbonic  Oxide-HsemogloMn. 

(3.)  CO-Hsemoglobin  is  a  more  stable  chemical  compound  than  the 
foregoing,  and  is  produced  at  once  when  carbonic  oxide  is  brought  into 
contact  with  pure  Hb  or  OgHb  (CI.  Bernard,  1857).  It  has  an 
intensely  florid  or  cherry-red  colour,  and  gives  two  absorption-bands, 
very  like  those  of  OoHb,  but  they  are  slightly  closer  together  and  lie 
more  towards  the  violet  (Fig.  11,  3).  Reducing  substances  (which  act 
upon  HbO.,)  do  not  affect  these  bands,  i.e.,  they  cannot  convert  the  CO 
compound  into  reduced  Hb.  Another  good  test  to  distinguish  it  from 
HbO.2  is  the  soda  test.  If  a  10  per  cent,  solution  of  caustic  soda  be 
added  to  a  solution  of  CO-Hb,  and  heated,  it  gives  a  cinnahar-red  colour; 
Avhile,  Avith  an  HbO.,  solution,  it  gives  a  dark-brown,  greenish,  greasy 
mass  (Hoppe-Seyler).  Oxidising  substances  [solutions  of  potassic 
permanganate  (0"025  per  cent),  potassic  chlorate  (5  per  cent.),  and 
dilute  chlorine  solution]  make  solutions  of  CO-Hb,  cherry-red  in 
colour,  while  they  turn  solutions  of  HbO.,  pale  yellow.  After  this 
treatment  both  solutions  show  the  absorption-bands  of  methaemoglobin. 
If  ammonium  sulphide  be  added,  HbO„  and  CO-Hb  are  re-formed. 

On  account  of  its  stability  CO-Hb  resists  external  influences  and  even  putre- 
faction for  a  long  time  (Hoppe-Seyler),  and  the  two  bands  of  the  spectrum  may  be 
visible  after  many  months.  Landois  obtained  the  soda  test  and  spectroscopic 
bands  in  the  blood  of  a  woman  poisoned  18  months  previously  by  CO,  and  after 
great  putrefaction  of  the  body  had  taken  place. 

If  CO  is  breathed  by  man,  or  if  air  containing  it  be  inspired,  it 
gradually  displaces  the  0,  volume  for  volume,  out  of  the  Hb  (L.  Meyer), 
and  death  soon  occurs;  1,000  ccm  inspired  at  once  will  kill  a  man. 
A  very  small  quantity  in  the  air  (t^o-toVo)  suflSces,  in  a  relatively 
short  time,  to  form  a  large  quantity  of  CO-Hb  (Gr^hant).  As 
continued  contact  with  other  gases  (such  as  the  passing  of  0  through 
it  for  a  very  long  time)  gradually  separates  the  CO  from  the  Hb 
(with  the  formation  of  02Hb — Bonders),  it  happens  that,  in  very  partial 
poisoning  with  CO,  the  blood  gradually  gets  rid  of  the  latter.  A 
high  degree  of  poisoning  necessitates  the  transfusion  of  blood  (p.  61). 

[Gamgee  and  Zuntz  also  find  that  although  the  CO-Hb  compound  is  very  stable, 
yet  it  may  be  reduced  by  passing  air  or  neutral  gases  through  it  for  a  lengthened 
period ;  it  is  also  reduced  when  blood  is  boiled  in  the  mercurial  pump.] 


32  POISONING  BY   CARBONIC   OXIDE, 

17.  Phenomena  of  Poisoning  by  Carbonic  Oxide.     Other 
Compounds  of  Haemoglobin. 

Carbonic  oxide  is  formed  during  incomplete  combustion  of  coal  or  coke,  and 
passes  into  the  air  of  the  room,  provided  there  is  not  a  free  outlet  for  the 
products  of  combustion.  It  occurs  to  the  extent  of  12-28  per  cent,  in  ordinary 
gas,  which  largely  owes  its  poisonous  x)roperties  to  the  presence  of  CO.  If  the  0 
be  gradually  displaced  from  the  blood  by  the  respiration  of  air  containing  CO,  life 
can  only  be  maintained  as  long  as  sufficient  O  can  be  obtained  from  the  blood  to 
support  the  oxidations  necessary  for  life.  Death  occurs  before  all  the  0  is  dis- 
placed from  the  blood.  CO  has  no  effect  when  directly  applied  to  muscle  and 
nerve.  When  it  is  inhaled,  there  is  first  stimulation  and  afterwards  paralysis  of 
the  nervous  system,  as  shown  by  the  symptoms  induced,  e.g.,  violent  headache, 
great  restlessness,  excitement,  increased  activity  of  the  heart  and  respiration, 
salivation,  tremors,  and  spasms.  Later,  unconsciousness,  weakness,  and  paralysis 
occur,  laboured  respiration,  diminished  heart-beat,  and  lastly,  complete  loss  of 
sensibility,  cessation  of  the  respiration  and  heart-beat,  and  death.  At  first 
the  temperature  rises  several  tenths  of  a  degree,  but  it  soon  falls  1°  or  more.  The 
pulse  is  also  increased  at  first,  but  afterwards  it  becomes  very  small  and  frequent. 

In  poisoning  with  pure  CO  there  is  no  dyspnoea,  but  sometimes  muscular  spasms 
occur,  the  coma  not  being  very  marked.  There  is  also  temporary  but  pronounced 
paralysis  of  the  limbs,  followed  by  violent  spasms.  After  death  the  heart  and 
brain  are  congested  with  intensely  florid  blood.  In  poisoning  with  the  vapour  of 
charcoal,  where  CO  and  CO2  both  occur,  there  is  a  varying  degree  of  coma ;  pro- 
nounced dyspnoea,  muscular  spasms  which  may  last  several  minutes,  gradual 
paralysis  and  asphyxia,  moniliform  contractions  and  subsequent  dilatation  of  the 
blood-vessels,  with  congestion  of  various  organs,  occur,  accompanied  by  a  fall  of  the 
blood-pressure  (Klebs),  indicating  initial  stimulation  and  subsequent  paralysis  of 
the  vaso-motor  centre.  This  also  explains  the  variations  in  the  temperature  and 
the  occasional  occurrence  of  sugar  in  the  urine  after  poisoning  with  CO.  After 
death,  the  blood-vessels  are  found  to  be  filled  with  fluid  blood  of  an  exquisitely 
bright  cherry-red  colour,  while  all  the  muscles  and  viscera  and  exposed  parts  of 
the  body  (such  as  the  lips)  have  the  same  colour.  The  brain  is  soft  and  friable, 
there  are  catarrh  of  the  respiratory  oi'gans  and  degeneration  of  the  muscles,  and 
great  congestion  and  degeneration  of  the  liver,  kidneys,  and  spleen.  The  spots  of 
lividity,  post-mortem,  are  bright  red.  After  recovery  from  poisoning  with  CO, 
there  may  be  paraplegia  and  (although  more  rarely)  disturbances  of  the  cerebral 
activity.  The  poisonous  action  of  the  vapours  of  combustion  was  known  to 
Aristotle. 

(4.)    Nitric   Oxide-Haemoglobin  (NO-Hb) — is  formed  when  NO  is 

brought  into  contact  with  Hb  (L.  Hermann). 

As  NO  has  a  great  affinity  for  0,  red  fumes  of  nitrogen  peroxide  (NO2)  being 
formed  whenever  the  two  gases  meet,  it  is  clear  that,  in  order  to  prepare  NO-Hb, 
the  0  must  first  be  removed.  This  may  be  done  by  passing  H  through  it,  [or 
ammonia  may  be  added  to  the  blood,  and  a  stream  of  NO  passed  through  it  ;  the 
ammonia  combines  with  all  the  acid  formed  by  the  uuion  of  the  NO  with  the 
O  of  the  blood].  NO-Hb  is  a  more  stable  chemical  comjiound  than  CO-Hb, 
which,  as  we  have  seen,  is  again  more  stable  than  02Hb.  It  has  a  bluish-violet 
tint,  and  also  gives  two  absorption-bands  in  the  spectrum  similar  to  those  of  the 
other  two  compounds,  but  not  so  intense.  These  bands  are  not  abolished  by  the 
action  of  reducing  agents. 

The  three  compounds  of  Hb,  with  0,  CO,  and  NO,  are  crystalline; 
like  Hb,  they  are  isomorphous,  and  their  solutions  are  not  dichroic.     One 


DECOMPOSITION   OF   HAEMOGLOBIN.  33 

gramme  Hb  unites  with   r33-l*35  c.c.m.  of  each  of  the  gases  at  0" 
and  1  metre  pressure  (Preyer,  L.  Hermann). 

(5.)  Cyanogen,  CNH  (Hoppe-Seyler),  and  acetylene,  C2H2  (Bistrow  and 
Liebreich),  form  easily  decomposable  compounds  with  Hb.  The  former  occurs  in 
poisoning  with  hydrocyanic  acid,  and  has  a  spectrum  identical  with  that  of  OoHb, 
and,  like  OoHb,  it  is  reduced  by  special  agents.  [The  existence  of  these  com- 
pounds is,  however,  highly  doubtful  (Gamgee).] 

(6.)  If  CO3  be  passed  through  a  sokition  of  oxyhaemoglobin  for  a  con- 
siderable time,  reduced  Hb  is  first  formed ;  but  if  the  process  be 
prolonged  the  Hb  is  decomposed,  a  precipitate  of  globulin  is  thrown 
down,  and  an  absorption-band,  similar  to  that  obtained  when  Hb  is 
decomposed  with  acids,  is  observed  (see  p.  33). 

18.  Decomposition  of  Haemoglobin. 

In  solution  and  in  the  dry  state  Hb  gradually  becomes  decomposed,  whereby 
the  iron-containing  pigment  haematin,  along  with  certain  bye-products,  formic, 
lactic,  and  butyric  acids  are  formed. 

Haemoglobin,  however,  may  be  decomposed  at  once  into — (1)  a  body 
containing  iron  hamiatin,  and — (2)  a  colourless  proteid  closely  related  to 
globulin  ; — by  (a.)  the  addition  of  all  acids,  even  by  CO2  in  the  presence 
of  plenty  of  water ;  (b.)  strong  alkalies ;  (c.)  all  reagents  which  coagulate 
albumin,  and  by  heat  at  70°-80°C. ;  (d.)  by  ozone. 

(A.)  H^MATiN  (Cgg,  H^Q,  Ng,  Fe^,  Ojo)  forms  about  4  per  cent,  of  ha3mo- 
globin  (dog).  It  is  insoluble  in  water,  alcohol,  and  ether;  soluble  in 
dilute  alkalies  and  acids,  and  in  acidulated  ether  and  alcohol. 

When  Hb  containing  0  is  decomposed,  hsematin  is  formed  at  once ;  while  Hb 
free  from  0  on  being  decomposed  forms  first  a  purplish-red  body,  HyEMOCHROMOGExV 
(C34,  H3G,  N4,  Fe  O5),  which  contains  less  0,  and  is  a  precursor  of  haematin.  In 
the  presence  of  0  it  becomes  oxidised,  and  passes  into  htematin.  In  solution  it 
gives  the  spectrum  shown  in  Fig.  II,  7  (Hoppe-Seyler).  Dilute  acids  in  an 
alkaline  solution  deprive  haemochromogen  of  its  iron,  and  h^emato-pokpiiybin,  a 
substance  which  remains  stable  in  contact  with  air,  is  produced.  It  may  also  be 
produced  from  hsematin  by  the  action  of  acids,  so  that  haematin  is  an  oxidation 
stage  of  ha3mochromogen. 

(a)  Hcematin  in  acid  solution. — Lecanu  extracted  it  from  dry  blood-corpuscles 
by  using  alcohol  containing  sulphuric  and  tartaric  acids.  If  acetic  acid  be  added 
to  a  solution  of  Hb,  a  mahogany-brown  fluid  is  obtained,  containing  hcematin  in  acid 
solution,  which  gives  a  spectrum  with  four  absorption-bands  in  the  yellow  and 
green  (Fig.  11,  5). 

(/3)  If  this  solution  be  treated  with  excess  of  ammonia,  hmmatin  in  alkaline  solu- 
tion is  formed,  which  gives  one  absorption-band  on  the  boundary  line  between  red 
and  yellow  (Fig.  11,  6). 

(y)  Reducing  agents  cause  this  band  to  disappear,  and  produce  in  the  yellow 
two  broad  bands,  which  are  due  to  the  presence  of  •'  reduced  hcematin  "  (Fig. 
11,7). 

(S)  When  haemoglobin  is  extravasated  into  the  subcutaneous  tissue,  it  becomes 
BO  altered  that  ultimately  hydrated  oxide  of  iron  appears  in  its  place. 

3 


34  HiEMIN   AND   BLOOD   TESTS.  . 

19.  Hsemin  and  Blood  Tests. 

In  1853  Teichmann  prepared  crystals  from  blood,  which  Hoppe- 
Seyler  showed  to  be  chloride  of  luematin  or  hydrochlorate  of  hsematin. 
The  presence  of  these  crystals  is  used  as  a  test  for  blood-stains  or 
blood  in  solution.  These  crystals  of  hsemin  (Fig.  1 2)  are  prepared  by 
adding  a  small  crystal  of  common  salt  to  dry  blood  on  a  glass  slide, 
and  then  an  excess  of  glacial  acetic  acid ;  the  whole  is  gently  heated 
until  bubbles  of  gas  are  given  off.  On  allowing  the  preparation  to 
cool,  the  characteristic  hsemin  crystals  are  obtained  (Hsematin,  +  2HC1). 

Characters. — When  well-formed,  the  crystals  are  small  microscopic 
rJiomUc plates,  or  rhombic  rods;  sometimes  they  are  single — at  other  times 
they  are  aggregated  in  groups,  often  crossing  each  other.  Some  kinds 
of  blood  (ox  and  pig)  yield  very  irregular,  scarcely  crystalline,  masses. 
The  crystalline  forms  of  hsemin  are  identical  in  all  the  different  kinds 
of  blood  that  have  been  examined  (Jahnke,  Hogyes).  They  are  doubly 
refractive  and  pleo-chromatic ;  by  transmitted  light  they  are  mahogany- 
brown,  and  by  reflected  light  bluish-black,  glancing  like  steel.  They 
give  a  brown  streak  on  porcelain. 

(1.)  Preparatiojl  from  Dry  Blood-Stains. — Place  a  few  particles 
of  the  blood-stain  on  a  glass  slide,  add  2  to  3  drops  of  glacial  acetic 
acid  and  a  small  crystal  of  common  salt;  cover  with  a  cover-glass, 
and  heat  gently  over  the  flame  of  a  spirit-lamp  until  bubbles  of  gas 
are  given  off.  On  cooling,  the  crystals  appear  in  the  preparation 
(Fig.  13). 


^V^  S\^ 


,.        V     , 


^  X^^^  i     '  ■        --^-^  .^./ 


Fig.  12.  Fig.  13. 

Hjemm  Crystals  of  various  forms.  Hsemin  Crystals  prepared  from 

traces  of  blood. 

(2.)  From  Stains  on  Porous  Bodies. — The  stained  object  (cloth, 
wood,  blotting-paper,  earth)  is  extracted  with  a  small  quantity  of  dilute 
caustic  potash,  and  afterwards  with  water  in  a  watch-glass.  Both 
solutions  are  carefully  filtered,  and  tannic  acid  and  glacial  acetic  acid 
are  added  until  an  acid  reaction  is  obtained.  The  dark  precipitate 
which  is  formed  is  collected  on  a  filter  and  washed.     A  small  part  of 


H^MIN   AND   BLOOD   TESTS,  35 

it  is  placed  on  a  microscope  slide,  a  granule  of  common  salt  is  added, 
and  the  whole  dried;  the  dry  stain  is  treated  as  in  (1.)   (Struwe). 

(3.)  From  Fluid  Blood. — Dry  the  blood  slowly  at  a  low  temperature, 
and  proceed  as  in  (1.) 

(4.)  From  very  Dilute  Solutions  of  Haemoglobin. — (a.)  Strmve's 
Method — Add  to  the  fluid,  ammonia,  tannic  acid,  and  afterwards  glacial 
acetic  acid,  until  it  is  acid;  soon  a  black  precipitate  of  tannate  of 
hsematin  is  thrown  down.  This  is  isolated,  washed,  dried,  and  treated 
as  in  (1.),  but  instead  of  NaCl  a  granule  of  ammonium  chloride  is  added. 

(6.)  Guning  and  r-an  Geuns  recommend  the  addition  of  zinc  acetate,  ■which  gives 
a  reddish  precipitate;  this  precipitate  is  to  be  treated  as  in  (1.) 

H?emin  crystals  may  sometimes  be  prepared  from  putrefying  or 
lake-coloured  blood,  but  they  are  very  small,  and  here  the  test  often 
fails.  "When  mixed  with  iron-rust,  as  on  iron-weapons,  the  blood- 
crystals  are  generally  not  formed.  In  such  cases,  scrape  off  the  stains 
and  boil  them  with  dilute  caustic  potash.  If  blood  be  present,  the 
dissolved  hsematiy  forms  a  fluid,  which  in  a  thin  layer  is  green  ;  in  a 
thick  layer  red  (H.  Eose). 

Chemical  Characters. — Hasmin  crystals  have  been  prepared  from  all  classes  of 
vertebrates  and  from  the  blood  of  the  earth-worm. 

They  are  insoluble  in  water,  alcohol,  ether,  chloroform  ;  but  H2SO4  dissolves 
them,  expelling  the  HCl,  and  giving  a  violet-red  colour.  Ammonia  also  dissolves 
them,  and  if  the  resulting  solution  be  evaporated,  heated  to  130°C.,  and  treated 
■with  boiling  water  (which  extracts  the  ammonium  chloride),  pure  hcematin  is 
obtained  (Hoppe-Seyler)  as  a  bluish-black  substance,  which  on  being  pounded  forms 
a  brown  and  amorphous  powder.  Its  solutions  in  caustic  alkalies  are  dichroic;  in 
reflected  light,  brownish-red;  in  transmitted  light,  in  a  thick  stratum,  red — in  a 
thin  one,  olive-green.     The  acid  solutions  are  monochromatic  and  brown. 

An  alcoholic  solution  of  hsematin,  when  reduced  by  tin  and  hydro- 
chloric acid,  yields  tirobilin  (Hoppe-Seyler),  (compare  Bile). 

20.  Haematoidin. 

VirchoAV  discovered  this  important  derivative  from  haemoglobin.  It 
.  occurs  in  the  body  wherever  blood  stagnates  outside  the  circulation,  and 
becomes  decomposed — as  when  blood  is  extravasated  into  the  tissues 
— e.g.,  the  brain — in  solidified  blood-plugs  (thrombus);  invariably  in  the 
Graafian  follicles.  It  contains  no  iron  (C3,,  Hgg,  N^,  Og),  and  crystallises 
in  clinorhombic  prisms  (Fig.  14)  of  a 
yeUowish-brown  colour.  It  is  soluble  in 
warm  alkalies,  carbon  disulphide,  benzol,  and 
chloroform.  Very  probably  it  is  identical  "with 
one  of  the  bile  pigments — hili-ruhin  (Valen- 
teiner).  [When  acted  upon  by  impure  nitric  IL;^  ^^  (\ 
acid  (Gmelin's  reaction),  it  gives  the  same  -p-^   14 

play  of  colours  as  bile.]  H^matoidln  Crystals. 


86  OTHER   CONSTITUENTS   OF   RED   CORPUSCLES. 

In  casevS  where  a  large  amount  of  blood  has  undergone  solution 
within  the  blood-vessels  (as  by  injecting  foreign  blood),  hsematoidin 
crystals  have  been  found  in  the  urine  (v.  Kecklinghausen,  Landois). 

21.    (B.)  The  Colourless  Proteid  of  Haemoglobin. 

It  is  closely  related  to  globulin ;  but,  while  the  latter  is  precipitated 
by  all  acids,  even  by  CO.,,  and  re-dissolved  on  passing  0  through  it, 
the  proteid  of  haemoglobin,  on  the  other  hand,  is  not  dissolved  after 
precipitation  on  passing  through  it  a  stream  of  0. 

As  crystals  of  haenioglobin  can  be  decolourised  under  special  circumstances,  it 
is  probable  that  these  owe  their  crystalline  form  to  the  proteid  which  they 
contain.  Landois  placed  crystals  of  h?emoglobin  along  with  alcohol  in  a  dialyser, 
putting  ether  acidulated  Avith  sulphuric  acid  outside,  and  thereby  obtained 
colourless  crystals.  [If  frog's  blood  be  sealed  up  on  a  microscopic  slide,  along 
with  a  few  drops  of  water  for  several  days,  long  colourless  acicular  crystals  are 
developed  in  it  (Stirling  and  Brito).] 

22.    II.  Proteids  of  the  Stroma. 

Dry  red  human  blood-corpuscles  contain  from  5'1 0-1 2*24  per  cent, 
of  these  proteids,  but  little  is  known  about  them  (Jiidell).  One  of 
them  is  glohuUn,  which  is  combined  with  a  body  resembling  nuclein 
(Wooldridge),  and  traces  of  a  diastatic  ferment  (v.  Wittich).  The 
stroma  tends  to  form  masses  which  resemble  fibrin  (Landois). 

L.  Brunton  found  a  body  resembling  mucin  in  the  nuclei  of  red  blood- corpuscles, 
and  Miescher  detected  nuclein. 


23.  The  Other  Constituents  of  Red  Blood-Corpuscles. 

III.  Lecithin  (0 •.35-0-72  per  cent.)  in  dry  blood-corpuscles  (Jiidell), 
and  also  in  brain,  yelk,  and  seminal  fluid. 

It  is  regarded  as  a  glycero-phosphate  of  neurin,  in  which,  in  the  radical  of 
glycero-phosphoric  acid,  two  atoms  of  H  are  replaced  by  two  of  the  radical  of 
stearic  acid.  By  gentle  heat  glycero-phosphoric  acid  is  split  up  into  glycerine  and 
phosphoric  acid. 

Cholesterin  (0-2.5  per  cent.); — no  Fats. 

These  substances  are  obtained  by  extracting  stromata  or  blood  itself  with  ether. 
When  the  ether  evaporates,  the  characteristic  globular  forms  ("  myelin-forms  ")  of 
lecithin  and  crystals  of  cholesterin  are  recognised.  The  amount  of  lecithin  may 
be  determined  from  the  amount  of  phosphorus  in  the  ethereal  extract. 

IV.  Water  (681 -03  per  1,000— C.  Schmidt). 

V.  Salts  (7*28   per    1,000, — C.    Schmidt),  chiefly  compounds   of 


ANALYSIS  OF  BLOOD.  37 

potash  and  phosphoric  add;  the  phosphoric  acid  is  derived  only  from 
the  burned  lecithin ;  Avhile  the  greater  part  of  the  sulphuric  acid  in 
the  analysis  is  derived  from  the  burning  of  the  haemoglobin. 

Analysis  of  Blood. — 1,000  parts,  by  weight,  of  horse's  blood  contain  :  — 

344'18  blood-corpuscles  (containing  about  128  per  cent,  of  solids). 
655'S2  plasma  (containing  about  10  per  cent,  of  solids). 

1,000  parts,  by  vveigbt,  of  moist  blood-coepuscles  contain: — 


Solids,  367*9 

(pig);  400-1  (ox). 

Water,  632  "1 

„      599-9    „ 

The  solids  are : — 

Pig. 

Ox. 

Haemoglobin, 

261- 

280-5 

Albumin, 

86-1 

107 

Lecithin,    Cholesterin,    and 

other  )        ^c,.n 

".- 

Organic  Bodies, 

.         .\         ^^" 

/  o 

Inorganic  Salts,     . 

8-9 

4-8 

/  Potash, 

5-543 

0-747 

1   Magnesia, 

0-158 

0-017 

Including     <    Chlorine, 

1-504 

1-635 

1  Phosphoric  Acid,             2-067 

0-703 

V  Soda,      . 

0 

2-093  (Bunge), 

24.  Chemical  Composition  of  the  Colourless 

Corpuscles. 

Investigations  have  been  made  on  pus  cells,  which  closely  resemble 
colourless  blood-corpuscles.  They  contain  several  protekls  ;  alkali  albu- 
minate, a  proteid  which  coagulates  at  48°C.,  and  another  resembling 
myosin,  fibrino-plastin,  and  a  coagulating  ferment;  nude'm  in  the 
nuclei  (!Miescher);  perhaps  also  glycogen  (Salomon),  lecithin,  and 
extractives. 

100  parts,  by  weight,  of  dry  PUS  contain: — 

Earthy  Phosphates,         .         .         0-416  |  Potash, 0-201 

Sodic  Phosphate,     •        .         .         0-606  I  Sodic  Chloride,        .         .         .         0-143 

25.  Blood-Plasma  and  its  Relation  to  Serum. 

The  imaltered  fluid  in  which  the  blood-corpuscles  float  is  called  ^^/asma, 
or  llqxior  sanguinis.  This  fluid,  however,  after  blood  is  withdrawn  from  the 
vessels,  rapidly  undergoes  a  change,  owing-  to  the  formation  of  a  solid 
fibrous  substance,  fibrin,  which  seems  to  be  produced  by  the  coming 
together  of  three  special  substances,  the  so-called  Jibriti-fadors.  After  this 
occurs,  the  new  fluid  which  remains  no  longer  coagulates  spontaneously 
(it  is  plasma,  ynimis  the  fibrin-factors),  and  is  called  serum.     Apart  from 


38  PREPAKATION   OF  PLASMA. 

the  presence  of  the  fibrin-factors,  the  chemical  composition  of  plasma 
and  serum  is  the  same. 

[When  blood  coagulates,  the  following  rearrangement  of  its  ele^ients  takes 
place : — 

Blood. 


Plasma.  Corpuscles,  ]  ^^^: 


Serum.  Fibrin. 


Fibrin,  Corpuscles,  and  some  Serum  (Blood  Clot).] 

The  serum,  however,  still  contains  a  portion  of  the  fibrin-ferment, 
and  also  some  of  the  fibrino-plastin  or  fibrino-plastic  substance. 
Plasma  is  a  clear,  transparent,  slightly  thickish  fluid,  which,  in  most 
animals  (rabbit,  ox,  cat,  dog),  is  almost  colomiess;  in  man  it  is 
yellow,  and  in  the  horse  citron-yellow. 

26.  Preparation  of  Plasma. 

(A.)  Without  Admixture. — Taking  advantage  of  the  fact  that 
plasma,  when  cooled  to  0°  outside  the  body,  does  not  coagulate  for  a 
considerable  time,  Briicke  prepares  the  plasma  thus: — Selecting  the 
blood  of  the  horse  (because  it  coagulates  slowly,  and  its  corpuscles  sink 
rapidly  to  the  bottom),  he  receives  it,  as  it  flows  from  an  artery,  in  a 
tall  narrow  glass,  placed  in  a  freezing-mixture,  and  cooled  to  0°.  The 
blood  remains  fluid,  and,  the  coloured  corpuscles  subsiding  in  a  few 
hours,  the  plasma  remains  above  as  a  clear  layer,  which  can  be  removed 
with  a  cooled  pipette.  If  this  plasma  be  then  passed  through  a  cooled 
filter,  it  is  robbed  of  all  its  colourless  corpuscles. 

[Burdon-Sanderson  uses  a  vessel  consisting  of  three  compartments 
— the  outer  and  inner  contain  ice,  while  the  blood  of  the  horse  is 
caught  in  the  central  compartment,  which  does  not  exceed  lialf-an-inch 
in  diameter.] 

The  quantity  of  plasma  may  be  roughly  (but  only  roughly)  estimated 
by  using  a  tall,  graduated  measuring-glass.  If  the  plasma  be  warmed, 
it  soon  coagulates  (owing  to  the  formation  of  fibrin),  and  passes  into 
a  trembling  jelly.  If,  however,  it  be  beaten  with  a  glass-rod,  the 
fibrin  is  obtained  as  a  white  stringy  mass,  adhering  to  the  rod.  The 
quantity  of  fibrin  in  a  given  volume  of  plasma  is  about  0'7  — 1  per 
cent.,  although  it  varies  much  in  different  cases. 


COAGULATION   OF  THE  BLOOD.  39 

(B.)  With  Admixture. — Blood  flowing  from  an  artery  is  caught  in  a 
tall  graduated  measure  containing  |tli  of  its  volume  of  a  concentrated 
solution  of  sodic  sulphate  (Hewson) — or  in  a  25  per  cent,  solution  of 
magnesic  sulphate  (1  vol.  to  4  vols,  blood :  Semmer) — or  1  vol.  blood 
with  2  vols,  of  a  4  per  cent,  solution  of  monophosphate  of  potash 
(Masia).  When  the  blood  is  mixed  Avith  these  fluids  and  put  in  a 
cool  place,  the  corpuscles  subside,  and  the  clear  stratum  of  plasma 
mixed  Avith  the  salts  may  be  removed  with  a  pipette.  If  the  salts  be 
removed  by  dialysis,  coagulation  occurs;  or  it  may  be  caused  by  the 
addition  of  water  (Joh.  MiiUer).  Blood  which  is  mixed  with  a  4  per 
cent,  solution  of  common  salt  does  not  coagulate,  so  that  it  also  may 
be  used  for  the  preparation  of  plasma.  [For  frog's  blood  Johannes 
Miiller  used  a  ^  per  cent,  solution  of  cane  sugar,  which  permits  the 
corpuscles  to  be  separated  from  the  plasma  by  filtration.  The  plasma 
mixed  Avith  the  sugar  coagulates  in  a  short  time.] 

27.  Fibrin— Coagulation  of  the  Blood. 

General  Characters. — Fibrin  is  that  substance  wliich,  becoming 
solid  in  shed  blood,,  in  plasma  and  in  lymph  causes  coagulation.  In 
these  fluids,  when  left  to  themselves,  fibrin  i^  formed,  consisting  of 
innumerable,  excessively  delicate,  closely-packed,  microscopic,  doubly 
refractive  (Hermann)  fibrils  (Fig.  6,  E).  These  fibrils  entangle  the 
blood-corpuscles  as  in  a  spider's  web,  and  form  with  them  a  jelly-like, 
solid  mass  called  the  blood-clot  {placenta  sanguinis).  At  first  the 
clot  is  very  soft,  and  after  the  first  2  to  15  minutes  a  few  fibres  may  be 
found  on  its  surface;  these  may  be  removed  with  a  needle,  while  the 
interior  of  the  clot  is  still  fluid.  The  fibres  ultimately  extend  throughout 
the  entire  mass,  which,  in  this  stage,  has  been  called  cruo7\  After 
from  12  to  15  hours  the  fibrin  contracts,  or,  at  least,  shrinks  more 
and  more  closely  around  the  corpuscles,  and  a  fairly  solid,  trembling, 
jelly-like  clot,  which  can  be  cut  with  a  knife,  is  formed.  During  this 
time  the  clot  has  expressed  from  its  substance  a  fluid — the  blood-serum. 
The  clot  takes  the  shape  of  the  vessel  in  which  the  blood  coagulates. 
Fibrin  may  be  obtained  by  washing  away  the  corpuscles  from  the 
clot  with  a  stream  of  water. 

Crnsta  Phlogistica. — If  the  corpuscles  subside  very  rapidly,  and  if 
the  blood  coagulates  slowly,  the  upper  stratum  of  the  clot  is  not  red, 
but  only  yellowish,  on  account  of  the  absence  of  coloured  corpuscles. 
This  is  regularly  the  case  in  horse's  blood,  and  in  human  blood  it  is 
observed  especially  in  inflammations ;  hence  this  layer  has  been  called 
crusta  plilogistica.  Such  blood  contains  more  fibrin,  and  so  coagulates 
more  slowly. 


40  PHENOMENA  OF   COAGULATION. 

The  crusta  is  fonnecl  under  other  circumstances,  but  the  cause  of  its  formation 
is  not  always  clear — e.g.,  with  increased  S.G.  of  the  corpuscles,  or  diminished  S.G. 
of  the  plasma  (as  in  hydremia  and  chlorosis),  whereby  the  corpuscles  sink  more 
rapidly,  and  also  during  pregnancy.  The  taller  and  narrower  the  glass,  the  thicker 
is  the  crusta  (compare  §  41).  The  upper  end  of  the  clot,  where  there  are  few 
corpuscles,  shrinks  more,  .and  is  therefore  smaller  than  the  rest  of  the  clot.  This 
upper,  lighter-coloured  layer  is  called  the  "  buffy"  coat ;  this,  however,  gradually 
passes  both  as  to  size  and  colour  into  the  normal  dark-coloured  clot.  [Sometimes 
the  upper  surface  of  the  clot  is  concave  or  cupped.  The  older  physicians  used  to 
attribute  great  importance  to  this  condition,  and  also  to  the  occurrence  of  the 
crusta  phlorjistica,  or  buffy  coat.  ] 

Defil)rmated  Blood. — If  freslily-shecl  blood  be  beaten  or  whipped 
with  a  glass-rod  or  with  a  bundle  of  twigs,  fibrin  is  deposited  on  the' 
rod  or  twigs  in  the  form  of  a  solid,  fibrous,  yellowish-white,  elastic 
mass,  and  the  blood  which  remains  is  called  "  defibrinated  blood."  [The 
twigs  and  fibrin  must  be  washed  in  a  stream  of  water  to  remove 
adhering  corpuscles.] 

Coagulation  of  Plasma. — Plasma  shows  phenomena  exactly  analogous, 
save  that  there  is  no  well-defined  clot,  owing  to  the  absence  of  the 
resisting  corpuscles ;  there  is,  however,  always  a  soft,  trembling  jelly 
formed,  when  plasma  coagulates. 

Properties  of  Fibrin. — Although  the  fibrin  appears  voluminous,  it 
only  occurs  to  the  extent  of  0'2  per  cent.  (O'l  to  0'3  per  cent.)  in  the 
blood.  The  amount  varies  considerably  in  two  samples  of  the  same 
blood  (Sig.  Mayer).  It  is  insoluble  in  water  and  ether;  alcohol  shrivels 
it  by  extracting  water ;  dilute  hydrochloric  acid  (O'l  per  cent.)  causes 
it  to  swell  up  and  become  clear,  and  changes  it  into  syntonin  or  acid- 
albumin.  When  fresh,  it  has  a  grayish-yellow  fibrous  appearance,  and 
is  elastic ;  when  dried,  it  is  horny,  transparent,  brittle,  and  friable. 

When  fresh  it  dissolves  in  6  to  8  per  cent,  solutions  of  sodium  nitrate  or 
sulphate,  in  dilute  alkalies,  and  in  ammonia — thus  forming  alkali-albuminate. 
Heat  does  not  coagulate  these  solutions.  If,  however,  to  a  solution  of  fibrin  in 
0'05  per  cent,  soda  solution,  there  be  added  acids,  or  (the  faintly  alkaline)  lactate, 
formate,  butyrate,  acetate,  or  valerianate  of  ammonia  or  soda,  coagulation  occurs 
(Deutschmann).     Hydric  peroxide  is  rapidly  decomposed  by  fibrin  (Thenard). 

According  to  H.  Nasse,  the  first  appearance  of  a  coagulum  occurs  in  man's 
blood  after  3  min.  45  sec,  in  woman's  blood  after  2  min.  20  sec.  Age  has  no  effect; 
withdrawal  of  food  accelerates  coagulation  (H.  Vierordt). 

28.  General  Phenomena  of  Coagulation. 

I.  Blood  which  is  in  direct  contact  with  the  living  and  unaltered 
blood-vessels  does  not  coagulate  (Briicke,  1857).  This  important  fact 
was  proved  by  Briicke,  who  filled  the  heart  of  a  tortoise  with  blood  which 
had  stood  15  minutes  exposed  to  the  air  at  0°,  and  kept  it  in  a  moist 
chamber.     The  blood  was  still  fluid  at  the  end  of  5^  hours,  while  the 


PHENOMENA  OF  COAGULATION.  41 

heart  itself  still  continued  to  beat.  He  observed  that  at  0°  the  blood 
was  uncoagulated  in  the  contracting  heart  of  a  tortoise  after  eight  days. 
Blood  inside  a  contracting  frog's  heart  preserved  under  mercury  does 
not  coagulate.  If  the  wall  of  the  vessel  be  altered  by  ])athological  pro- 
cesses {e.g.,  if  the  intima  becomes  rough  and  uneven,  or  undergoes 
inflammatory  change)  coagulation  is  apt  to  occur  at  these  places. 
Blood  rapidly  coagulates  in  a  dead  heart,  or  in  blood-vessels  (but  not 
in  capillaries)  or  other  canals  {e.g.,  the  ureter)  (Virchow). 

If  blood  stagnates  in  a  living  vessel,  coagulation  begins  in  the  central 
axis,  because  here  there  is  no  contact  with  the  wall  of  the  living  blood- 
vessel. This  influence  of  the  wall  of  blood-vessels  was,  to  some  extent, 
known  to  Thackrah  (1819)  and  to  Sir  Astley  Cooper. 

II.  Conditions  which  Hinder  or  Delay  Coagulation. — {a.)  The 
addition  of  small  quantities  of  alkalies  and  ammonia,  or  of  con- 
centrated solutions  of  neutral  salts  of  the  alkalies  and  earths  (alkaline 
chlorides,  sulphates,  phosphates,  nitrates,  carbonates).  Magnesic 
sulphate  acts  most  favourably  in  delaying  coagulation  (1  vol.  solution 
of  28  per  cent,  to  3^  vol.  blood  of  the  horse). 

(5.)  The  precipitation  of  the  fibrinoplastin  by  adding  weak  acids,  or 
by  CO^. 

By  the  addition  of  acelic  acid  until  the  reaction  is  acid,  the  coagulation  is  com- 
pletely arrested.  A  large  amount  of  COo  delays  it,  and  hence  venous  blood 
coagulates  more  slowly  than  arterial.  Heuce,  also,  the  blood  of  siijj'ocated  persons 
remains  fluid. 

(c.)  The  addition  of  egg-albumin,  syrup,  glycerine,  and  much  icater. 
If  uncoagulated  blood  be  brought  into  contact  with  a  layer  of  already- 
formed  fibrin,  coagulation  occurs  later. 

{(l.)  By  cold  at  0°  coagulation  may  be  delayed  for  one  hour 
(J.  Davy.)  If  blood  is  frozen  at  once,  after  thawing,  it  is  still  fluid, 
and  then  coagulates  (Hewson).  When  shed  blood  is  under  high 
pressure  it  coagulates  slowly  (Landois). 

(e.)  ^\oo^  oi  embryo-fowls  does  not  coagulate  before  the  12th  or  14th 
day  of  incubation  (Boll);  that  of  the  hepatic  vein  very  slightly; 
menstrual  blood  shows  little  tendency  to  coagulate  when  alkaline  mucus 
from  the  vagina  is  mixed  with  it.  If  it  be  rapidly  discharged,  it 
coagulates  in  masses. 

(/.)  Blood  rich  in  fibrin  from  inflamed  parts  coagulates  slowly.  In  "  bleeders  " 
(hsemophilia),  coagulation  seems  not  to  take  place,  owing  to  a  want  of  the  sub- 
stances producing  fibrin  ;  hence,  in  these  cases,  wounds  of  vessels  are  not  plugged 
with  fibrin.  Albertoni  observed  that  if  tryptic  pancreas  ferment  (dissolved  in 
glycerine),  be  injected  into  the  blood  of  an  animal,  blood  does  not  coagulate. 
Schmidt-Miilheim  found  that  after  the  injection  of  ^5«ve  ijeptone  into  the  blood 
(0"3  to  0*6  grammes  per  kilo. )  of  a  dog,  the  blood  lost  its  power  of  coagulating. 
A  substance  is  formed  in  the  plasma,  which  prevents  coagulation,  but  which  is 


42  PHENOMENA  OF  COAGULATION. 

precipitated  by  COg.    Lymph  behaves  similarly  (Fano),   After  peptones  are  injected, 
there  is  a  great  solution  of  leucocytes  in  the  blood  (v,  Samson-Himmelstjerna). 

III.  Coagulation  is  Accelerated — (a.)  By  Contact  with  Foreign 
Substances  of  all  kinds;  hence,  threads  or  needles  introduced  into 
arteries  are  rapidly  covered  with  fibrin.  Even  the  introduction  of 
air-bubbles  into  the  circulation  accelerates  it,  and  the  pathologically 
altered  wall  of  a  vessel  acts  like  a  foreign  body.  Blood  shed  from 
an  artery  rapidly  coagulates  on  the  walls  of  vessels,  on  the  surfaces 
exposed  freely  to  air,  and  on  the  rods  or  twigs  by  which  it  is  beat. 
The  passage  through  it  of  indifferent  gases,  such  as  N.  and  H.,  and 
the  addition  of  HgO  have  the  same  effect. 

(5.)  Heating  from  39°  to  55°C.,  rapidly  facilitates  coagulation 
(Hewson). 

(c.)  Agitation  of  the  blood,  as  shown  by  Hewson  and  Hunter. 

IV.  (Eapidity  of  Coagulation. — Amongst  vertebrates,  the  blood  of 
birds  (especially  of  the  pigeon),  coagulates  almost  momentarily;  in 
cold-blooded  animals,  coagulation  occurs  much  more  slowly,  while 
mammals  stand  midway  between  the  two.  [The  blood  of  a  fowl  begins 
to  coagulate  in  a-haif  to  one  and  a-half  minute ;  that  of  a  pig,  sheep, 
rabbit,  in  a-half  to  one  and  a-half  minute ;  of  a  dog,  one  to  three 
minutes ;  of  a  horse  and  ox,  five  to  thirteen  minutes ;  of  man,  three 
to  four  minutes ;  solidification  is  completed  in  nine  to  eleven  minutes, 
but  rather  sooner  in  the  case  of  women  (Nasse)  ].  The  blood  of 
invertebrates,  which  is  usually  colourless,  forms  a  soft  whitish  clot  of 
fibrin.     Even  in  lymph  and  chyle,  a  small  soft  clot  is  formed. 

v.  When  coagulation  occurs,  the  aggregate  condition  of  the  fibrin- 
factors  is  altered,  so  that  heat  must  he  set  free  (Valentin,  1884,  Schiffer, 
L6pine).  The  rise  in  the  temperature  may  be  ascertained  with  a  very 
delicate  thermometer. 

VI.  In  blood  shed  from  an  artery,  the  degree  of  alkalinity  diminishes 
from  the  time  of  its  being  shed  until  coagulation  is  completed  (Pfliiger 
and  Zuntz).  This  is  probably  due  to  a  decomposition  in  the  blood, 
whereby  an  acid  is  developed,  which  diminishes  the  alkalinity  (p.  2). 

VII-  Whether  or  not  elect7'icity  is  developed,  is  not  positively  proved.  Hermann 
supposes  that  the  parts  already  coagulated  are  negative,  while  non-coagulated 
parts  are  positive;  but  this  has  not  been  clearly  shown. 

VIII.  During  coagulation  there  is  a  diminution  of  the  0  in  the  blood, 
although  a  similar  decrease  also  occurs  in  non-coagulated  blood.  Traces 
of  ammonia  are  also  given  off,  which  Eichardson  erroneously  supposed 
to  be  the  cause  of  the  coagulation  of  the  blood.  [This  is  refuted — (1.) 
by  the  fact  that  blood,  when  collected  under  mercury  (whereby  no 
escape  of  ammonia  is  possible),  also  coagulates ;  and  (2.)  by  the  follow- 


CAUSES   OF   COAGULATION.  43 

ing  experiment  of  Lister : — He  placed  two  ligatures  on  a  vein  con- 
taining blood,  moistening  one-half  of  the  outer  surface  of  the  vein 
with  ammonia,  and  leaving  the  other  half  intact.  The  blood  coagu- 
lated in  the  first  half,  and  not  in  the  other^  owing  to  the  properties  of 
the  wall  of  the  vein  of  the  former  being  altered.  Lister  also  proved 
that  blood  will  remain  fluid  for  hours  in  a  vein  after  it  has  been 
freely  exposed  to  the  air,  and  even  after  it  has  been  poured  in  a  thin 
stream  from  one  vein  to  another.]  Neither  the  decrease  of  0  nor  the 
evolution  of  ammonia  seems  to  have  any  causal  connection  with  the 
formation  of  fibrin. 

29.  Cause  of  the  Coagulation  of  the  Blood, 

Alexander  Schmidt  stated  that  fibrin  is  formed  by  the  coming 
together  of  two  jjroteid  substances  which  occur  dissolved  in  the  plasma 
or  liquor  sanguinis,  viz. : — (1.)  Fibrinogen,  i.e.,  the  substance  which  yields 
the  chief  mass  of  the  fibrin,  and  (2.)  Fibrino])lastic  substance  or  fibrino- 
plastin.  In  order  to  determine  the  coagulation  a  ferment  seems  to  be 
necessary,  and  this  is  supplied  by  (3.)  the  fibrin-ferment. 

[The  serous  sacs  of  the  body  contain  a  fluid  which  in  some  respects  closely 
resembles  lymph.  The  pericardium  contains  pericardial  fluid,  which  in  some 
animals  coagulates  spontaneously  [e.g.,  in  the  rabbit,  ox,  horse,  and  sheep),  if 
the  fluid  be  removed  immediately  after  death.  If  this  be  not  done  till  several 
hours  after  death,  the  fluid  does  not  coagulate  sjjontaneously.  The  fluid  of 
the  tunica  vaginalis  of  the  testis,  again,  sometimes  accumulates  to  a  great 
extent,  and  constitutes  hydrocele,  but  this  fluid  shows  no  tendency  to  coagulate 
spontaneously.  Andrew  Buchanan  found,  however,  that  if  to  the  fluid  of  ascites, 
to  pleuritic  fluid,  or  to  hydrocele  fluid,  there  be  added  clear  blood-serum,  then 
coagulation  takes  place,  i.e.,  two  fluids — neither  of  which  shows  any  tendency  hy 
itself  to  coagulate — form  a  clot  when  they  are  mixed.  He  also  found  that  if 
"washed  blood  clot"  (which  consists  of  a  mixture  of  fibrm  and  colourless  cor- 
puscles) be  added  to  hydrocele  fluid,  coagulation  occurred.  Denis  mixed  unco- 
agulated  blood  with  a  saturated  solution  of  sodic  sulphate,  allowed  the  corpuscles 
to  subside,  and  decanted  the  clear  fliud  which  was  mixed  with  sodic  chloride, 
until  a  lai-ge  amount  of  precipitate  had  been  obtained.  The  precipitate,  when 
washed  with  a  saturated  solution  of  sodic  chloride,  he  called  J3las7nine.  If  plas- 
mine  be  mixed  with  water,  it  coagulates  spontaneously,  resulting  in  the  formation 
of  fibrin,  while  another  proteid  remains  in  solution.  According  to  the  view  of 
Denis,  fibrin  is  produced  by  the  splitting  up  of  plasmine  into  two  bodies — fibrin 
and  an  insoluble  proteid.] 

[Besearches  of  A.  Schmidt- —This  observer  rediscovered  the  chief  facts 
already  known  to  Buchanan,  viz.,  that  some  fluids  which  do  not  coagulate 
spontaneously,  clot  when  mixed  with  other  fluids,  which  also  show  no  tendency 
to  coagulate  spontaneously,  e.g.,  hydrocele  fluid  and  blood-serum.  He  pi'oceeded 
to  isolate  from  these  fluids  the  bodies  which  are  described  as  fibrinogen  and 
fibriuoplastin.  The  bodies  so  obtained  were  not  pure,  but  Schmidt  supposed  that 
the  formation  of  fibrin  was  due  to  the  interaction  of  these  two  proteids.  The 
reason  why  hydrocele  fluid  did  not  coagulate,  he  said,  was  that  it  contained 
fibrinogen  and  no  fibriuoplastin,  while  blood -serum  contained  the  latter,  but  not 


44  THE   FIBRIN-FACTORS. 

the  former.  Schmidt  afterwards  discovered  that  these  two  substances  may  be 
present  in  a  fluid,  and  yet  that  coagulation  may  not  occur  [e.g.,  occasionally  in 
hydrocele  fluid).  He  supposed,  therefore,  that  blood  or  blood-serum  contained 
some  other  constituent  necessary  for  coagulation.  This  he  afterwards  isolated 
in  an  impure  condition  and  c&WeA.  fihrin-ferment  (Gamgee).  ] 

Properties  of  these  Substances. — Fibrinogen  and  fibrinoplastin  are 
iiot  distinguished  from  each  other  by  well-marked  chemical  characters. 
Still  they  differ  as  follows  : — 

(a.)  Fibrinoplastin  is  more  easily  precipitated  from  its  solutions  than 
fibrinogen. 

(b)  It  is  more  readily  redissolved  when  once  it  is  precipitated. 

(c.)  It  forms  when  precipitated  a  very  light  granular  powder. 

(d)  Fibrinogen  adheres  as  a  sticky  deposit  to  the  side  of  the  vessel. 
It  coagulates  at  56°C. 

Both  substances  closely  resemble  globulin  in  their  chemical  composi- 
tion (Kiihne  called  fibrinoplastin  faraglobulin),  and  in  their  reactions 
they  are  not  unlike  myosin.  Like  all  globulins,  they  require  a  trace  of 
common  salt  for  their  solution. 

On  account  of  their  great  similarity,  both  substances  are  not  usually 
prepared  from  blood-plasma.  Fibrinogen  is  prepared  from  serous  trans- 
udations (pericardial,  abdominal,  or  pleuritic  fluid,  or  the  fluid  of 
hydrocele),  which  contain  no  fibrinoplastin.  Fibrinoplastin  is  most 
readily  prepared  from  serum,  in  which,  there  is  still  plenty  of .  fibrino- 
plastin, but  no  fibrinogen. 

Preparation  of  Fibrinoplastin. — (a.)  Dilute  blood-serum  with  twelve 
times  its  volume  of  ice-cold  water,  and  almost  neutralise  it  with  acetic 
acid,  [add  4  drops  of  a  25  per  cent,  solution  of  acetic  acid  to  every 
120  CO.  of  diluted  serum];  or  (b.)  pass  a  stream  of  carbonic  acid  through 
the  diluted  serum,  which  soon  becomes  turbid;  and  after  a  time  a 
fine  white  powder,  copious  and  granular,  is  precipitated  (Schmidt, 
1862). 

[(c. )  The  serum  may  be  dialysed  for  a  day  ;  at  the  end  of  this  time  the  contents 
of  the  dialyser  have  become  turbid,  and  when  a  current  of  CO2  is  passed  through 
them,  a  precipitate  of  fibrinoplastin  is  obtained.  Schmidt's  fibrinoplastin  has 
also  been  called  serum-globulin  (Hammarsten)  or  paraglobulin  (Kuhne).] 

Schmidt  found  that  100  c.c.  of  the  serum  of  ox  blood  yielded  07  to  0-8  grms.; 
horse  serum,  0'3  to  0*56  grms.  of  dry  fibrinoplastin.  Fibrinoplastin  occurs  not 
only  in  serum,  but  also  in  red  blood-corpuscles,  in  the  fluids  of  connective  tissue, 
and  in  the  juices  of  the  cornea. 

[(fZ.)  Method  of  Hammarsten. — All  the  fibrinoplastin  in  serum  is 
not  precipitated  either  by  adding  acetic  acid  or  by  COj.  Hammarsten 
found,  however,  that  if  crystals  of  magnesium  sulphate  be  added  to 
complete  saturation,  it  precipitates  the  whole  of  the  serum-globulin, 
but  does  not  precipitate  serum-albumin  (Gamgee) ;  it   seems    tliat  in 


THE   FIBRIN-FACTORS.  45 

the  ox  and  horse  serum-globuliu  is  more  abundant  than  serum-albumin, 
while  in  the  dog  and  rabbit  the  reverse  obtains.] 

Preparation  of  Fibrinogen. — This  is  best  prepared  from  hydrocele 
fluid,  although  it  may  also  be  obtained  from  the  fluids  of  serous 
cavities — e.g.,  the  pleura,  pericardium,  or  peritoneum.  It  does  not 
exist  in  blood-serum,  although  it  does  exist  in  blood-plasma,  lymph,  and 
chyle,  from  which  it  may  be  obtained  by  a  stream  of  COo,  after  the 
paraglobulin  is  precipitated.  ((/.)  Dilute  hydrocele  fluid  with  ten  to 
fifteen  times  its  volume  of  water,  and  pass  a  stream  of  CO;,  through  it ; 
or  (h.)  carefully  neutralise  it  by  adding  acetic  acid,  (c.)  Add  powdered 
common  salt  to  saturation  to  a  serous  transudation,  when  a  sticky 
glutinous  (not  very  abundant)  precipitate  of  fibrinogen  is  obtained. 

[Hammarsten  and  Eichwald  find  that,  although  paraglobulin  and 
fibrinogen  are  soluble  in  solutions  of  common  salt  (containing  5  to  8 
per  cent,  of  the  salt),  a  saline  solution  of  12  to  16  per  cent,  is 
required  to  precipitate  the  fibrinogen,  leaving  still  in  solution  para- 
globulin, which  is  not  precipitated  until  the  amount  of  salt  exceeds 
20  per  cent.  (Gamgee).] 

Hammarsten  found  that  it  may  be  prej^ared  from  blood  (of  the 
horse)  by  first  precipitating  all  the  serum-globulin  or  fibrinoplastin 
with  crystals  of  magnesium  sulphate,  and  subsequent  filtration,  which 
removes  the  corpuscles ;  a  clear  salted  plasma  is  thus  obtained.  If  to 
the  filtrate  a  saturated  solution  of  common  salt  be  added,  a  turbid, 
flaky,  impure  precipitate  of  fibrinogen  is  obtained.  This  may  be  dis- 
solved in  dilute  common  salt,  and  again  precipitated  by  a  saturated 
solution  of  NaCl. 

Properties  of  the  Fibrin-Factors. — They  are  insoluble  in  pure  uater,  but 
dissolve  in  water  containing  O  in  solution.  Both  are  soluble  in  very  dilute 
alkalies — e.g.,  caustic  soda,  and  are  precipitated  from  this  solution  bj'  COo.  They 
are  soluble  in  dilute  common  salt — like  all  globulins— but  if  a  certain  amount  of 
common  salt  be  added  in  excess  they  are  precipitated.  Very  dilute  hydrochloric 
acid  dissolves  them,  but  after  several  hours  they  become  changed  into  a  body 
resembling  syntonin  or  acid-albumin. 

Fibrinogen  dissolved  in  a  weak  solution  of  common  salt  (1  to  5  per  cent.)  is 
re-precipitated  on  addhig  water,  so  that  it  resembles  fibrin.  Its  solution  in 
common  salt  coagulates  at  52''  to  55°C.  (Hammarsten,  Fred^ricq). 

[Fredericq  finds  that  fibrinogen  exists  as  such  in  the  plasma,  it  coagulates  at 
56°C.,  and  the  plasma  thereafter  is  uncoagulable  (Gamgee).] 

Preparation  of  the  Fibrin-Ferment. — Mix  blood-serum  (ox)  with 
twenty  times  its  volume  of  strong  alcohol,  and  filter  off  the  deposit 
thereby  produced  after  one  month.  The  deposit  on  the  filter  consists 
of  albumin  and  the  ferment ;  dry  it  carefully  over  sulphuric  acid,  and 
reduce  to  a  powder.  Triturate  1  gramme  of  the  powder  with  65  c.c.m. 
of  water  for  ten  minutes,  and  filter.    The  ferment  is  dissolved  by  the 


46  FORMATION    OF    FIBRIN. 

water,  and  passes   through   the  filter,  while  the  coagulated  albumin 
remains  behind  (Schmidt). 

In  the  preparation  of  fibrinoplastin,  the  ferment  is  carried  down  with  it 
mechanically.  The  ferment  seems  to  be  formed  first  in  fluids  outside  the  body, 
very  probably  by  the  solution  of  the  colourless  corpuscles.  More  ferment  is  formed 
in  the  blood  the  longer  the  interval  between  its  being  shed  and  its  coagulation. 
It  is  destroyed  at  80°C. 

[Gamgee'S  Method. — Buchanan's  "washed  blood-clot"  (p.  43)  is  digested  in 
an  8  per  cent,  solution  of  common  salt.  The  solution  so  obtained  possesses  in  an 
intense  degree  the  properties  of  Schmidt's  fibrin-ferment.] 

Coagulation  Experiments. — According  to  A.  Schmidt,  if  the  pure 
solutions  of  (1)  fibrinogen,  (2)  fibrinoplastin,  and  (3)  fibrin-ferment 
be  mixed,  fibrin  is  formed.  The  process  goes  on  best  at  the  tem- 
perature of  the  body ;  it  is  delayed  at  0° ;  and  the  ferment  is 
destroyed  at  the  boiling  point.  The  presence  of  0  seems  necessary 
for  coagulation.  The  amount  of  ferment  appears  to  be  immaterial; 
large  quantities  produce  more  rapid  coagulation,  but  the  amount  of 
fibrin  formed  is  not  greater. 

The  amount  of  salts  present  has  a  remarkable  relation  to  coagulation. 
Solutions  of  the  fibrin-factors  deprived  of  salts,  and  redissolved  in 
very  dilute  caustic  soda,  when. mixed,  do  not  coagulate  until  sufficient 
NaCl  be  added  to  make  a  1  per  cent,  solution  of  this  salt  (Schmidt). 

When  blood  or  blood-plasma  coagulates,  all  the  fibrinogen  is  used 
up,  so  that  the  serum  contains  only  fibrinoplastin  and  fibrin-ferment; 
hence,  the  addition  of  hydrocele  fluid  (which  contains  fibrinogen)  to 
serum  causes  coagulation. 

According  to  Hammarsten,  fibrin  is  formed  when  the  ferment  is 
added  to  a  solution  of  fibrinogen. 

[Hammarsten's  Theory  of  Coagulation. — Hammarsten's  researches  lead 
him  to  believe  that  fibrinoplastin  is  quite  unnecessary  for  coagulation.  According 
to  him,  fibrin  is  formed  from  one  body,  viz.,  jihrinogen,  which  is  present  in  plasma 
when  it  is  acted  upon  by  the  Jihrin-ferment ;  the  latter,  however,  has  not  been 
obtained  in  a  pure  state.  Neither  he  nor  Schmidt  asserts  that  this  body  is  of 
the  nature  of  a  ferment,  although  they  use  the  term  for  convenience.  It  is  quite 
certain  that  fibrin  may  be  formed  when  no  fibrinoplastin  is  present,  coagulation 
being  caused  by  the  addition  of  calcic  chloride  or  casein  prepared  in  a  special  way. 
But,  whether  one  or  two  proteids  be  required,  in  all  cases  it  is  clear  that  a 
certain  quantity  of  salts,  especially  of  NaCl,  is  necessary.] 

30.  Source  of  the  Fibrin-Factors. 

Al.  Schmidt  maintains  that  all  the  three  substances  out  of  which 
fibrin  is  said  to  be  formed,  arise  from  the  breaking  up  of  colourless 
blood-corpuscles.  In  the  blood  of  man  and  mammals  fibrinogen  exists, 
dissolved  in  the  circulating  blood  as  a  dissolution   product  of  the 


SOURCES   OF  THE  FIBRIN-FACTORS.  47 

retrogressive  changes  of  the  white  corpuscles.  Plasma  contains 
dissolved  fibrinogen  and  serum-albumin.  The  circulating  blood  is 
very  rich  in  lymph  or  white  cells,  much  richer,  indeed,  than  was 
formerly  supposed  (Schmidt,  Landois).  As  soon  as  blood  is  shed  from 
an  artery,  enormous  numbers  of  the  colourless  corpuscles  are  dissolved 
(Mantegazza) — according  to  Alex.  Schmidt  71 '7  per  cent,  (horse). 
First,  the  body  of  the  cell  disappears,  and  then  the  nucleus  (Hlava). 
The  products  of  their  dissolution  are  dissolved  in  the  plasma,  and  one 
of  these  products  is  fihrinoplasfm.  At  the  same  time  the  fibrin-ferment 
is  also  produced,  so  that  it  would  seem  not  to  exist  in  the  intact  blood- 
corpuscles.  Fibrinoplastin  and  fibrin-ferment  are  also  produced  by 
the  "  transition  forms "  of  blood-corpuscles,  i.e.,  those  forms  which  are 
intermediate  between  the  red  and  the  white  corpuscles.  They  seem  to 
break  up  immediately  after  blood  is  shed.  The  hlood-plates  (p.  21), 
are  also  probably  sources  of  these  substances. 

In  amphibians  and  birds,  the  red  nucleated  corpuscles  rapidly 
break  up  after  blood  is  shed,  and  yield  the  substance  or  substances 
which  form  fibrin.  Al.  Schmidt  convinced  himself  that  in  these 
animals  fibrinogen  is  also  a  constituent  of  the  blood-corpuscles. 

It  is  clear,  therefore,  according  to  Schmidt's  view,  that  as  soon  as 
the  blood-corpuscles,  white  or  red,  are  dissolved,  the  fibrin-factors  pass 
into  solution,  and  the  formation  of  fibrin  by  the  union  of  the  three 
substances  will  ensue. 

[It  is  worthy  of  remark  to  recall  the  conclusion  arrived  at  by  And, 
Buchanan,  viz.,  that  the  potential  element  of  his  "washed  blood-clot"  resided 
in  the  colourless  corpuscles,  "primary  cells  or  vesicles."  He,  like  Schmidt,  found 
that  the  bufFy-coat  of  horse's  blood,  which  is  very  rich  in  white  corpuscles, 
produced  coagulation  rapidly.  Buchanan  compared  the  action  of  his  washed  clot 
to  that  of  rennet  in  coagulating  milk.] 

Pathological. — Al.  Schmidt  and  his  pupils,  Jakowicki  and  Birk,  have  shown 
that  some  ferment,  probably  derived  from  the  dissolution  of  colourless  corpuscles, 
is  found  in  circulating  blood,  and  that  it  is  more  abundant  in  venous  than  in 
arterial  blood,  while  it  is  most  abundant  in  shed  blood.  It  is  specially  remarkable 
that  in  septic  fever  the  amount  of  ferment  in  blood  may  increase  to  such  an  extent 
as  to  permit  the  occurrence  of  spontaneous  coagulation  (thrombosis),  which  may 
even  produce  death  (Arn.  Kiihler).  In  febrile  cases  generally,  the  amount  of 
ferment  is  somewhat  more  abundant  (Edelberg  and  Birk).  After  the  injection 
of  ichor  into  the  blood  an  enormous  number  of  colourless  corpuscles  are  dissolved 
(F.  Hoffmann). 

31.  Relation  of  the  Red  Blood-Corpuscles  to  the 
Formation  of  Fibrin. 

That  the  red  blood-corpuscles  may  participate  in  the  production  of 
fibrin  is  proved  by  many  experiments. 


48  RED  CORPUSCLES   AND  FIBRIN-FORMATION, 

Hoppe-Seyler  showed  that  the  nucleated  blood-corpuscles  of  birds, 
when  treated  with  water,  give  a  copious  precipitate  which  resembles 
fibrin.  Heynsius  observed  a  similar  result  after  the  blood  of  fowls 
had  been  acted  upon  by  water  and  dilute  solution  of  common  salt,  and 
he  also  states  that  nearly  90  per  cent,  of  the  total  fibrin  may  be 
obtained  from  the  washed  blood-corpuscles  of  the  horse,  when  the 
corpuscles  are  gradually  dissolved.  Semmer  discovered  that  he  could 
cause  defibrinated  frog's  blood  to  coagulate  by  mixing  it  with  4  to  6  times 
its  volume  of  water.  On  adding  10  to  12  drops  of  a  0*2  per  cent, 
solution  of  soda  to  1  c.c.m.  of  defibrinated  frog's  blood,  Semmer  and  A. 
Schmidt  found  that  it  became  converted  into  a  structureless  glutinous 
mass,  in  which  neutralisation  with  acetic  acid  produced  fibres  of  fibrin. 
No  fibrin  was  formed  from  serum.  The  same  observers  diluted  4  c.c.m. 
of  defibrinated  frog's  blood  with  20  c.c.m.  of  water  containing  CO2. 
The  haemoglobin  was  thereby  dissolved  in  the  Avater,  while  the  colour- 
less stromata  fell  to  the  bottom.  When  this  deposit  was  mixed  with  a 
solution  of  sodium  hydrate,  a  similar  glutinous  mass  was  obtained, 
which  yielded  fibrin  on  being  neutralised  with  acetic  acid.  No  such 
result  was  obtained  from  haemoglobin. 

In  1874,  Landois  observed  under  the  microscope  that  the  stromata 
of  the  red  blood- corpuscles  of  mammals  passed  into  fibrin.  If  a  drop 
of  defibrinated  rabbit's  blood  be  placed  in  serum  of  frog's  blood,  with- 
out mixing  them,  the  red  corpuscles  can  be  seen  collecting  together ; 
their  surfaces  are  sticky,  and  they  can  only  be  separated  by  a  certain 
pressure  on  the  cover-glass,  whereby  some  of  the  new  spherical 
corpuscles  are  drawn  out  into  threads.  The  corpuscles  soon  become 
spherical,  and  those  at  the  margin  allow  the  haemoglobin  to  escape, 
when  the  decolourisation  progresses,  from  the  margin  inwards,  until  at 
last  there  remains  a  mass  of  stroma  adhering  together.  The  stroma- 
substance  is  very  sticky,  but  soon  the  cell-contours  disappear,  and  the 
stromata  adhere  and  form  fine  fibres.  Thus  (according  to  Landois) 
the  formation  of  fibrin  from  red  blood-corpuscles  can  be  traced  step  by 
step.  The  red  corpuscles  of  man  and  animals,  when  dissolved  in  the 
serum  of  other  animals,  show  much  the  same  phenomena. 

Stroma-Fibrin  and  Plasma-Fibrin. — Landois  calls  fibrin  formed 
direct  from  stroma,  stroma-fibrin.  Fibrin  which  is  formed  in  the  usual 
way  by  the  fibrin-factors  he  calls  iMsma-fibrin.  The  stroma-fibrin  is 
closely  related  chemically  to  stroma  itself;  and  as  yet  the  two  kinds  of 
fibrin  have  not  been  sharply  distinguished  chemically.  Substances  which 
rapidly  dissolve  red  corpuscles  cause  extensive  coagulation,  e.g.,  injection 
of  bile  or  bile  salts,  or  lake-coloured  blood,  into  arteries  (Naunyn  and 
Francken).  After  the  injection  of  foreign  blood  the  newly-injected 
blood  often   breaks  up  in  the   blood-vessels  of  the  recipient,  while 


COMPOSITION   OF  PLASMA   AND    SERUM.  49 

the  finer  vessels  are  frequently  found   plugged  with  small   thrombi 
(see  Transfusion,  p.  61). 

Coagulable  Fluids. — ^Vith  regard  to  coagulability,  Huids  containing  proteida 
may  be  classified  thus :  — 

(I.)  Those  that  coarjidafe  sjwnianeousbj,  i.e.,  blood,  lymph,  chyle. 

(2.)  Those  capable  of  coagulating,  e.g.,  fluids  secreted  pathologically  in  serous 
cavities  ;  for  example,  hydrocele  fluid,  which,  as  usually  containing  fibrinogen  only, 
does  not  coagulate  spontaneously,  coagulates  on  the  addition  of  fibrinoplastin  and 
ferment  (or  of  blood-serum  in  which  both  occur). 

(3.)  Those  which  do  not  coagulate,  e.g.,  milker  seminal  fluid,  which  do  not  seem 
to  contain  fibrinogen. 

32.  Chemical  Composition  of  the  Plasma  and 

Serum. 

I.  Proteids  occur  to  the  amount  of  8  to  1 0  per  cent,  in  the  plasma. 
Only  0*2  per  cent,  of  these  go  to  form  fibrin.  When  coagulation  has 
taken  place,  and  after  the  separation  of  the  fibrin,  the  plasma  becomes 
converted  into  serum.  The  S.  G.  of  human  serum  is  1,027  to  1,029.  It 
contains  several  proteids.  [According  to  Hammarsten,  human  serum 
contains  9 "207 5  per  cent,  of  solids, — of  these,  3*1 03  :=  serum-globulin, 
and  4*.516  =  serum-albumin,  i.e.,  in  the  ratio  of  1  :  1*511.] 

(a.)  Serum-Globulin  (Th.  Weyl)  or  Para-Globulin  2  -  4  p.  c,  was 
formerly  believed  to  occur  in  much  smaller  amount  than  it  actually 
does.  Hammarsten  found  that  if  serum  be  diluted  with  two  volumes 
of  Avater,  and  crystals  of  magnesium  sulphate  be  added  to  saturation, 
serum-globulin  is  precipitated,  but  not  serum-albumin.  In  the  serum 
of  the  horse  and  ox  serum-globulin  is  more  abundant  than  serum- 
albumin,  while  in  the  serum  of  the  rabbit  and  dog  the  reverse  is 
the  case.  It  is  soluble  in  10  per  cent,  solution  of  common  salt,  and 
coagulates  at  7-5 °C. 

[Serum-globulin  was  carefully  described  by  Panum  under  the  name  of  "  Serum - 
casein;"  by  Al.  Schmidt,  as  " Fibrino-plastic  substance;"  and  by  Kiihne,  as 
"Para-globulin. "] 

As  already  mentioned,  it  may  also  be  precipitated,  in  part,  by  diluting  serum 
^ith  10  to  15  vols,  of  water,  and  passing  a  stream  of  CO2  through  it  (p.  44).  If  a 
trace  of  acetic  acid  be  added  to  serum  after  the  separation  of  the  serum-globulin, 
Kiihne  finds  that  a  fine  precipitate  of  what  he  calls  soda-albuminate  occurs.  [It 
is,  however,  highly  doubtful  if  an  alkali-albuminate  does  occur  in  the  blood. 
Hammarsten  found  that  CO2  does  not  precipitate  all  the  serum-globulin,  so  that 
it  is  improbable  that  Kiihne's  soda-albuminate  exists  as  a  distinct  substance 
in  serum.] 

According  to  A.  E.  Burckhard,  magnesium  sulphate  not  only  precipitates 
serum -globulin,  but  also  another  proteid  substance  more  closely  resembling 
albumin.     During  hunger  the  globulin  increases  and  the  albumin  diminishes. 

(6.)  Serum- Albumin. — Its  solutions  begin  to  be  turbid  at  60°C., 
and  coagiUation   occurs  at   73°C.,  the  fluid  becoming   slightly  more 

4 


50  COMPOSITION    OF   PLASMA   AND    SERUM. 

alkaline  at  the  same  time.  The  amount  is  about  3  -  4  p.  c.  (Fr^dericq). 
If  sodium  chloride  be  cautiously  added  to  serum,  the  coagulating 
temperature  may  be  lowered  to  50°C.  It  has  a  rotatory  power  of  —  5  6°. 
It  is  changed  into  syntonin  or  acid-albumin  by  the  action  of  dilute 
HCl,  and  by  dilute  alkalies  into  alkali-albuminate. 

[Although  serum-albumin  is  closely  related  to  egg-alhumin  they  differ  : 
(a.)  as  regards  their  action  upon  polarised  light;  (6.)  ^'^e  precipitate  produced  by 
adding  HCl  or  HNO3  is  readily  soluble  in  4  c.c.m.  of  the  reagent  in  the  case  of 
serum-albumin,  while  the  precipitate  in  egg-albumin  is  dissolved  with  very  great 
difficulty ;  (c.)  egg-albumin,  injected  into  the  veins,  is  excreted  in  the  urine  as  a 
foreign  body,  while  serum-albumin  is  not  (Stockvis). 

Serum-albumin  has  never  been  obtained  free  from  salts,  even  when  it  is  dialysed 
for  a  very  long  time,  as  was  maintained  by  Aronstein,  whose  results  have  not  been 
confirmed  by  Heynsius,  Haas,  Huizinga,  Salkowski,  and  others.] 

After  all  the  para-globulin  (serum-globulin)  in  serum  is  precipitated  by 
magnesium  sulphate,  serum-albumin  still  remains  in  solution.  If  this  solution 
be  heated  to  40  or  50°C.  a  copious  precipitate  of  non-coagulated  serum-albumin  is 
obtained,  which  is  soluble  in  water.  If  the  serum-albumin  be  filtered  from  the 
fluid,  and  if  the  clear  fluid  be  heated  to  over  60°C.,  Fred6ricq  foiind  that  it  becomes 
turbid  from  the  precipitation  of  other  proteids ;  the  amount  of  these  other  bodies, 
however,  is  small, 

II.  Fats  (0*1  to  0'2  j)er  cent.). — Neutral  fats  (tristearin,  tripalmitin, 
triolein)  occur  in  the  blood  in  the  form  of  small  microscopic  granules, 
which,  after  a  meal  rich  in  fat  (or  milk),  render  the  serum  cpiite 
milky. 

The  amount  of  fat  in  the  serum  of  fasting  animals  is  about  0'2  per 
cent.;  during  digestion  0"4  to  0*6  per  cent.;  and  in  dogs  fed  on  a  diet 
rich  in  fat  it  may  be  1"25  per  cent.  There  are  also  minute  traces  of 
fatty  acids  (succinic).  Kohrig  showed  that  soluble  soajos — i.e.,  alkaline 
salts  of  the  fatty  acids — cannot  exist  in  the  blood.  [Cholesterin  may 
be  considered  along  with  the  fats.  It  occurs  in  considerable  amount 
in  nerve-tissues,  and,  like  fats,  is  extracted  by  ether  from  the  dry 
residue  of  blood-serum.  Hoppe-Seyler  found  0"019  to  0*314  per  cent. 
in  the  serum  of  the  blood  of  fattened  geese.  There  is  no  fat  in  the  red 
blood-corpuscles  (Hoppe-Seyler).  Lecithin  (and  protagon)  occur  in 
serum  and  also  in  the  blood-corpuscles,] 

III.  Traces  of  Grape  Sugar  (0'05  per  cent.)  occur  normally  in 
blood  and  serum,  and  also  a  trace  of  glycogen. 

The  amount  of  grape  sugar  in  the  blood  increases  with  the  absorption  of  sugar 
from  the  intestine,  and  tliis  increase  is  most  obvious  in  the  blood  of  the  portal 
and  hepatic  veins;  there  is  also  a  slight  increase  in  the  arterial  blood,  but  there  it 
is  rapidly  changed.  The  presence  of  sugar  is  ascertained  by  coagulating  blood  by  • 
boiling  it  with  sodium  sulphate,  pressing  out  the  fluid  and  testing  it  for  sugar 
with  Fehling's  solution  (CI.  Bernard).     Pa^^  coagulates  the  blood  with  alcohol. 

.  IV.    Extractives. — Kreatin,  urea  (0;01  to  0'085  per  cent,  in  the ; 


rOMPOSTTION    OF    PLAS^rA    AND    SERUM.  51 

dog),  hippuric  acid,  succinic  acid,  and  uric  acid  (more  abundant  in  gouty 
conditions),  hypoxanthin,  all  occur  in  very  small  amounts. 

The  plasma  and  serum  contain  a  yelloV'  pigment,  or  perhaps  several 
pigments.  One  of  these  is  called  cholepyrrhin  (horse,  calf),  and  is 
identical  with  the  bile  pigment  of  the  same  name  (Hammarsten). 
[Rabbit's  serum  is  colourless.]  Thudichum  regards  the  yellow  pigment 
as  lutein  ;  Maly,  as  hydrobilirubin;  and  MacMunn  as  choletelin. 

V.  Sarcolactic  Acid  and  Indican,  also  in  small  amount. 

VI.  Salts. —  The  amount  of  inorganic  salts  ('085  to  '09  per  cent.) 
contained  in  the  serum  is  slightly  less  than  in  the  plasma,  as  a  small 
amount  of  lime  and  magnesic  phosphate  is  removed  by  the  fibrin 
(Briicke).  The  most  abundant  salt  is  sodium  chloride  (O'o  per  cent.), 
and  next  to  it  wdium  carhonafc  [which  exists  in  the  plasma,  most 
probably  in  the  condition  of  sodium  hydric  carbonate  (NaHCOg). 
There  is  a  small  amount  of  potassic  chloride,  and  also  sulphuric  and 
phosphoric  acids,  lime  and  magnesia.  It  is  most  important  to  note 
that  the  soda  salts  are  far  more  abundant  in  the  serum  than  the 
potassium  salts.     The  ratio  may  be  as  high  as  10:1.] 

Salts  in  human  blood-serum  (Hoppe-Seyler). 


Sodic    Chloride. 

, ,  Sulphate, 

, ,  Carbonate, 

, ,  Phosphate, 

Calcic  Phosphate, 
Magnesic       ,,  .         . 

VII.  Water  about  90  per  cent. 


4'92  per  1000. 

0-44 
0-21 
0-15 

0-73 


33.  The  Gases  of  tlie  Blood. 

Absorption   of  Gases   by   Solid   Bodies   and   by  Fluids. 

Absorption  by  Solid  Bodies. — A  considerable  attraction  exists  between  the 
particles  of  solid  porous  bodies  and  gaseous  substances,  so  that  gases  are  attracted 
and  condensed  within  the  pores  of  solid  bodies — i.e.,  the  gases  are  absorbed. 
Thus,  one  volume  of  boxwood  charcoal  (at  12°C.  and  ordinary  barometric  pressure) 
absorbs  35  volumes  COo — 9'4  vol.  O— 7"5  vol.  N — 1'75  vol.  H.  Heat  is  always 
formed  when  gases  are  absorbed,  and  the  amount  of  heat  evolved  bears  a  relation 
to  the  energy  with  which  the  absorption  takes  place.  Non-porous  bodies  are 
similarly  invested  by  a  layer  of  condensed  gases  o)i  their  surface. 

By  Fluids. — Fluids  can  also  absorb  gases.  A  known  quantit;/  of  fluid  at 
different  pressures  always  absorbs  the  Srt??ie  volume  of  gas.  Whether  the  pressure 
be  great  or  small,  the  volume  of  the  gas  absorbed  is  equally  great  (W.  Henry). 
But  according  to  Boyle  and  Mariotte's  law  (1679),  when  the  pressure  within  the 
same  volume  of  gas  is  increased,  the  volume  varies  inversely  as  the  pressure. 

Hence  it  follows  that,  with  varying  pressure,  the  volume  of  gas  absorbed  remains 


52  GASES   OF  THE   BLOOD, 

the  same,  but  the  quantity  of  gas  (loeight,  density)  is  directly  proportional  to  the 
pressure.  If  the  pressure  =  0,  the  weight  of  the  gas  absorbed  must  also  =  0. 
As  a  necessary  result  of  this,  we  see  that  (1.)  fluids  can  he  freed  of  their  absorbed 
gases  in  a  vacuum  under  an  air-jyumjJ. 

Coefi5.Cieilt  of  absorption  means  the  volume  of  a  gas  (at  O'C)  which  is  absorbed 
by  a  unit  of  volume  of  a  liquid  (at  760  mm.  Hg)  at  a  given  temperature.  The  volume 
of  a  gas  absorbed,  and  therefore  the  coefficient  of  absorption,  is  quite  independent 
of  the  pressure,  while  the  vjeight  of  the  gas  is  proportional  to  it.  TemiJerature  has 
an  important  influence  on  the  coefficient  of  absorption.  With  a  low  temperature, 
it  is  greatest;  it  diminishes  as  the  temperature  increases;  and  at  the  boiling  point 
it  =  0.  Hence,  it  follows  that — (2.)  Absorbed  gases  may  be  expelled  from  fluids 
simply  by  causing  the  fluids  to  boil.  The  coefficient  of  absorption  diminishes  for 
different  fluids  and  gases,  with  increasing  temperature,  in  a  special,  and  by  no 
means  uniform,  manner,  which  must  be  determined  empirically  for  each  liquid 
and  gas.  Thus  the  coefficient  of  absorption  for  COg  in  water  diminishes  with  an 
increasing  temperature,  while  that  for  H  in  water  remains  unchanged  between 
0  and  20T. 

Dijffusioii  and  Absorption  of  Gases. 

Diffusion  of  Gases. — Gases  which  do  not  enter  into  chemical  combinations  with 
each  other,  mix  with  each  other  in  quite  a  regular  proportion.  If,  e.g.,  the  necks 
of  two  flasks  be  placed  in  communication  by  means  of  a  glass  or  other  tube,  and  if 
the  lower  flask  contain  COo,  and  the  upper  one  H,  the  gases  mix  quite  indepen- 
dently of  their  different  spedflc  gravities,  both  gases  forming  in  each  flask  a  perfectly 
uniform  mixture.  This  phenomenon  is  called  the  diffusion  of  gases.  If  a  porous 
membrane  be  pre\dously  inserted  between  the  gases,  the  exchange  of  gases  still 
goes  on  through  the  membrane.  But  (as  with  endosmosis  in  fluids)  the  gases  pass 
with  unequal  rapidity  through  the  pores,  so  that  at  the  beginning  of  the  experi- 
ment a  larger  amount  of  gas  is  found  on  one  side  of  the  membrane  than  on  the 
other.  According  to  Graham,  the  rapidity  of  the  diffusion  of  the  gases  through 
the  pores  is  inversely  proportional  to  the  square  root  of  their  specific  gravities. 
(According  to  Bun  sen,  however,  this  is  not  quite  correct.) 

Different  Gases  forming  a  Gaseous  Mixture  do  not  Exert  Pressure 
upon  one  another. — Gases,  therefore,  pass  into  a  space  filled  with  another  gas, 
as  they  would  pass  into  a  vacuum.  If  the  surface  of  a  fluid  containing  absorbed 
gases  be  placed  in  contact  with  a  very  large  quantity  of  another  gas,  the  absorbed 
gases  diff'use  into  the  latter.  Hence,  absorbed  gases  can  be  removed  by  (3.) 
passing  a  stream  of  another  goji  through  the  fluid,  or  by  merely  shaking  up  the  fluid 
with  another  gas. 

If  two  or  more  gases  are  mixed  in  a  closed  space  over  a  fluid,  as  the  different 
gases  existing  in  a  gaseous  mixture  exert  no  pressure  upon  each  other,  the  several 
gases  are  absorbed.  The  weight  of  each  absorbed  is  proportional  to  the  pressure 
under  which  each  gas  would  be,  were  it  the  only  gas  in  the  space.  This  pressure 
is  called  the  partial  pressure  of  a  gas  (Bunsen).  The  absorption  of  gases  from  their 
mixtures,  therefore,  is  proportional  to  the  partial  p>ressure.  The  partial  pressure 
of  a  gas  in  a  space  is  at  the  same  time  the  expression  for  the  tension  of  the  gas 
absorbed  by  a  fluid. 

The  air  contains  0-2096  volume  of  0,  and  0-7904  volume  N.  If  1  volume  of 
the  air  be  placed  under  a  pressure,  P,  over  water,  the  partial  pressure  under  which 
0  is  absorbed  =  0-2096  .  P  ;  that  for  N,  =  0-7904  .  P.  At  0°C.,  and  760  m.m. 
pressure,  1  volume  of  Avater  absorbs  002477  volume  of  air,  consisting  of  0-00862 
volume  0,  and  0-01615  volume  N.  It  contains,  therefore,  34  per  cent.  0,  and 
66  per  cent.  N.  Therefore,  v)ater  absorbs  from  the  air  a  mixture  of  gases  containing 
a  larger  percentage  of  0  than  the  air  itself. 


GASES   OF   THE   BLOOD. 


53 


34.  Extraction  of  the  Blood  Gases. 

The  extraction  of  the  gases  from  the  blood,  and  their  collection  for  chemical 
analysis,  are  carried  out  by  means  of  the  mercurial  jnimp  (C.  Ludwig).  Fig.  15 
shows  in  a  diagrammatic  form  the  arrangement  of  Pfliiger's  gas-pump. 

It  consists  of  a  receptacle  for  the  blood,  or  "blood-bulb"'  (A),  a  glass- 
globe  capable  of  containing  250  to  ."300  c. cm.,  connected  above  and  below  with 
tubes,  each  of  which  is  provided  with  a  stop-cock,  a  and  b  ;  b  is  an  ordinary  stop- 
cock, while  a  has  through  its  long  axis  a  perforation  which  opens  at  x,  and  is 
so  arranged  that,  according  to  the  position  of   the  hamile,  it  leads  up  into  the 


Fig.  15. 


Scheme  of  Pfliiger's  gas-pump— A,  blood-bulb;  a,  stop-cock,  with  a  longitudinal 
perforation  opening  upwards  ;  a',  the  same  opening  downwards ;  b  and  c, 
stop-cocks;  B,  froth -chamber ;  d,  e,  f,  stop-cocks;  G,  drying-chambers, 
containing  sulphuric  acid  and  pumice-stone ;  D,  tube,  with  manometer,  y. 


54  EXTRACTION   OF  THE   BLOOD-GASES. 

blood  bulb  (position  x,  a),  or  downwards  through  the  lower  tube  (position 
x',  a').  This  blood-bulb  is  first  completely  emptied  of  air  (by  means  of  a  mercurial 
air-pump),  and  then  carefully  weighed.  One  end  (cc')  of  it  is  tied  into  an  artery 
or  a  vein  of  an  animal,  and  when  the  lower  stop- cock  is  placed  in  the  position 
[x  a)  blood  flows  into  the  receptacle.  When  the  necessary  amount  of  blood  is 
collected,  the  lower  stop-cock  is  put  into  the  position,  x',  a',  and  the  blood- 
bulb,  after  being  cleaned  most  carefully,  is  weighed  to  ascertain  the  weight  of  the 
amount  of  blood  collected.  The  second  part  of  the  apparatus  consists  of  the  froth- 
chamber,  B,  leading  upwards  and  downwards  into  tubes,  each  of  which  is  pro- 
vided with  an  ordinary  stop-cock,  c  and  cl.  The  froth-chamber,  as  its  name 
denotes,  is  to  catch  the  froth  which  is  formed  during  the  energetic  evolution  of  the 
gases  from  the  blood.  The  lower  aperture  of  the  froth-chamber  is  connected  by 
means  of  a  well-ground  tube  with  the  blood-bulb,  while  above  it  communicates 
with  the  third  part  of  the  apparatus,  the  drying-chamber,  G.  This  consists  of  a 
U  -shaped  tube,  provided  below  with  a  small  glass-bulb,  which  is  half  filled  with 
sulphuric  acid,  while  in  its  limbs  are  placed  pieces  of  pumice-stone  also  moistened 
with  sulphuric  acid.  As  the  blood-gases  pass  through  this  apparatus  (which  may 
be  shut  off  by  the  stop-cocks,  e  and/)  they  are  freed  fi'om  their  watery  vaiMur  by 
the  sulphuric  acid,  so  that  they  pass  quite  dry  through  the  stop-cock,  /.  The 
short  weU-groimd  tube,  D,  is  fixed  to/,  and  to  the  former  is  attached  the  small 
barometric  tuhe  or  manometer,  y,  which  indicates  the  extent  of  the  vacuum.  From 
D  we  pass  to  the  pump  proper.  This  consists  of  two  large  glass-bulbs  which  are 
continued  above  and  below  into  open  tubes  ;  the  lower  tubes,  Z  and  xo,  being 
imited  by  a  caoutchouc  tube,  G.  Both  the  bulbs  and  the  caoutchouc  tube  contain 
mercury— the  bulbs  being  about  half-full,  and  F  being  larger  than  E.  The  bulb, 
E,  is  fixed ;  but  F  can  be  raised  or  lowered  by  means  of  a  jiuUey  with  a  rack  and 
pinion  motion.  If  F  be  raised,  E  is  filled ;  if  F  be  lowered,  E  is  emptied.  The 
upper  end  of  E  divides  into  two  tubes,  g  and  h.  of  which  g  is  united  to  D.  The 
ascending  tube,  h — gas-delivery  tube — is  very  narrow,  and  is  bent  so  that  its 
free  end  dips  into  a  vessel  containing  mercury  (v)— a  pneumatic  trough — and  the 
opening  is  placed  exactly  under  the  tube  for  collecting  the  gases,  the  eudiometer, 
J,  which  is  also  fiUed  with  mercury.  Where  g  and  H  unite,  there  is  a  two-way 
stop -cock,  which  in  one  position,  H,  places  E  in  connnunication  with  A,  B,  G,  D 
the  chambers  to  be  exhausted,  and  in  the  position,  K,  shuts  off  A,  B,  G,  D,  and 
places  the  bulb,  E,  in  communication  with  the  gas-delivery  tube,  h,  and  the 
eudiometer,  J. 

B,  G,  D  are  completely  emptied  of  air,  thus  : — The  stop-cock  is  placed 
in  the  position,  K ;  raise  F  until  drops  of  mercury  issue  from  the  fine  tube,  i  (not 
yet  placed  under  J) ;  place  the  stop-cock  in  the  position  H,  lower  F  ;  stop-cock  in 
position,  K,  and  so  on  until  the  barometer,  y,  indicates  a  complete  vacuum.  J  is 
now  placed  over  i.  Open  the  cocks,  c  and  b,  so  that  the  blood-bulb,  A,  communi- 
cates with  the  rest  of  the  apparatus,  and  the  blood-gases  froth  up  in  B,  and  after 
being  dried  in  G  pass  towards  E.  Lower  F,  and  they  pass  into  E ;  stop-cock 
in  position,  K,  raise  F,  and  the  gases  are  collected  in  J  under  mercury.  The 
repeated  lowering  and  raising  of  F  with  the  corresponding  position  of  the  stop- 
cocks ultimately  drives  all  the  gases  into  J.  The  removal  of  the  gases  is  greatly 
facilitated  by  placing  the  blood-bulb.  A,  in  a  vessel  containing  water  at  60°C. 

It  is  well  to  remove  the  gases  from  the  blood  immediately  after  it  is  collected 
from  a  blood-vessel,  because  the  0  undergoes  a  diminution  if  the  blood  be  kept. 
Of  course,  in  making  several  analyses  it  is  difl&cult  to  do  this,  and  the  best  plan  to 
pursue  in  that  case  is  to  keep  the  receptacles  containing  the  blood  on  ice. 

Mayow  (1670)  observed  that  gases  were  given  off  from  blood  in  vacuo.  Magnus 
(1837)  investigated  the  percentage  composition  of  the  blood-gases.  The  more 
important  recent  investigations  have  been  made  by  Lothar  Meyer  (1857),  and  by 
the  pupils  of  C.  Ludwig  and  E.  Pfluger. 


ESTIMATION   OF  THE  BLOOD-GASES.  55 

35.  duantitative  Estimation  of  the  Blood-Gases. 

The  gases  obtained  from  blood  consist  of  0,  CO2  and  N.  Pfliiger 
obtained  (at  0°C.  and  1  metre  Hg  pressure),  47'3  volumes  per  cent, 
consisting  of 

O  16-9  per  cent.  -  COo  29  per  cent.  -  N.  1'4  per  cent. 
As  is  shown  in  Fig.   15,  the  gases  are  obtained  in  an  eudiometer, 
i.e.,  in  a  narrow  tube,  J,  closed  at  one  end,  and  with  a  very  exact  scale 
marked  on  it,  and  having  two  fine  platinum  wires  melted  into  its  upper 
end,  with  their  free-ends  projecting  into  the  tube  (p  and  n). 

(1.)  Estimation  of  the  CO2.— A  small  ball  oi  fused  caustic  2>otash,  fixed  on  a 
platinum  wire,  is  introduced  into  tlie  mixture  of  gases  tlirough  the  lower  end  of 
the  eudiometer  under  cover  of  the  mercuiy.  The  surface  of  the  potash  ball  it 
moistened  before  it  is  introduced.  The  CO2  unites  with  the  potash  to  form 
potassium  carbonate.  After  it  has  been  in  for  a  considerable  time  (24  hours),  it 
is  withdrawn  in  a  similar  manner.  The  diminution  in  volume  indicates  the 
amount  of  COo  absorbed. 

(2.)  Estimation  of  the  0.— («•)  -Just  as  in  estimating  the  COo,  a  ball  ol  plios- 
pliorus  on  a  platinum  wire  is  introduced  into  the  eudiometer  (Bertholet);  it 
absorbs  the  0  and  forms  phosphoric  acid.  Another  plan  is  to  employ  a  small 
liapier-mache  ball  saturated  with  j}yro<jalUc  acid  in  caustic  potash,  which  rapidly 
absoi'bs  O  (Liebig).  After  the  ball  is  removed,  the  diminution  in  volume 
indicates  the  quantity  of  0. 

(b.)  The  0  is  most  easily  and  accurately  estimated  by  cxplodimj  it  in  the 
eudiometei-  (Volta  and  Bunsen).  Introduce  a  sufficient  quantity  of  H  into 
the  eudiometer,  and  accurately  ascertain  its  volume ;  an  electrical  spark  is 
now  passed  between  the  wires,  i)  and  n,  through  the  mixture  of  gases ;  the  0  and  H 
unite  to  form  water,  which  causes  a  diminution  in  the  volume  of  the  gases  in  the 
eudiometer,  of  which  ^  is  due  to  the  0  used  to  form  water  (HoO). 

(c.)  Estimation  of  the  N. — When  the  CO2  and  0  are  estimated  by  the  above 
method,  the  remainder  is  pure  N. 

36.  The  Blood  Gases. 

I.  Oxygen  exists  in  arterial  blood  (dog)  on  an  average  to  the 
extent  of  17  volumes  per  cent,  (at  0°C.  and  1  metre  Hg  pressure) 
(Pfliiger).  According  to  Pfliiger,  arterial  blood  (dog)  is  saturated  to 
Yi)  with  0,  while,  according  to  Hiifner,  it  is  saturated  to  the  extent 
of  yi.  In  venous  blood  the  quantity  varies  very  greatly;  in  the  blood 
of  a  passive  muscle  6  volumes  per  cent,  have  been  found ;  while  in  the 
blood  after  asphyxia  it  is  absent,  or  occurs  only  in  traces.  It  is 
certainly  more  abundant  in  the  comparatively  red  blood  of  active 
glands  (salivary  glands,  kidney),  than  in  ordinary  dark  venous  blood. 

The  0  in  Blood  occurs — («.)  simphj  ahsorhed  in  the  plasma.  This  is 
only  a  minimal  amount,  and  does  not  exceed  what  distilled  water 
at  the  temperature  of  the  body  would  take  up  at  the  partial  pressure 
of  the    0    in    the    air  of  the  lungs  (Lotliar  Meyer).     According  to 


56  THE   BLOOD-GASES. 

Fernet,  serum  takes  up  slightly  more  0  than  corresponds  to  the 
pressure,  and  this  is,  perhaps,  due  to  the  trace  of  haemoglobin  con- 
tained in  the  plasma  or  the  serum,  and  which  is  derived  from  the 
solution  of  red  corpuscles. 

(b.)  Almost  the  total  0  of  the  blood  is  chemically  united,  and,  therefore, 
not  subject  to  the  law  of  absorption.  It  is  loosely  united  to  the 
haemoglobin  of  the  red  corpuscles,  with  which  it  forms  oxyhcemoglobin 
(p.  29). 

The  absorption  of  this  quantity  of  0  is  completely  independent  of  pressure; 
hence,  animals  confined  in  a  closed  space  until  they  are  nearly  asphyxiated,  can 
use  up  almost  all  the  0  from  the  surrounding  atmosphere.  The  fact  of  the  union 
being  independent  of  pressure  is  proved  by  the  following : — The  blood  only  gives 
off  copiously  its  chemically  united  O,  when  the  atmospheric  pressure  is  lowered 
to  20  millimetres,  Hg.  (Worm  Miiller) ;  and,  conversely,  blood  only  takes  up  a 
little  more  O  when  the  pressure  is  increased  to  6  atmospheres  (Bert). 

Physical  Methods  of  obtaining  0  from  Blood. — Notwithstanding 
this  chemical  union  between  the  Hb  and  0,  however,  the  total  0  of  the 
blood  can  be  expelled  from  its  state  of  combination  by  those  means 
which  set  free  absorbed  gases — (a.)  by  introducing  blood  into  a  torri- 
cellian  vacuum ;  (b.)  by  boiling ;  (c.)  by  the  conduction  of  other  gases 
[H,]Sr,CO  or  NO]  through  the  blood,  because  the  chemical  union 
of  the  oxyhaemoglobin  is  so  loose  that  it  is  decomposed  even  by  these 
physical  means. 

Chemical  Reagents. — Amongst  chemical  reagents  the  following  re- 
ducing substances— ammonium  sulphide,  sulphuretted  hydrogen,  alkaline 
solutions  of  sub-salts,  iron  filings,  &c.,  rob  blood  of  its  0  (p.  30). 

AVith  regard  to  the  taking  up  of  0,  the  total  quantity  of  blood  behaves 
exactly  like  a  solution  of  haemoglobin  free  from  0  (Preyer.)  The 
amount  of  iron  in  the  blood  (0'55  in  1,000  parts)  stands  in  direct 
relation  to  the  amount  of  Hb ;  this  to  the  quantity  of  blood-corpuscles ; 
and  this,  in  turn,  to  the  specific  gravity  of  the  blood.  The  amount  of 
0  in  the  blood,  therefore,  is  nearly  proportional  to  the  specific  gravity 
of  the  blood,  and  it  is  also  in  proportion  to  the  amount  of  iron  in  the 
blood.  Picard  affirms  that  2-36  grammes  of  iron  in  the  blood  can 
fix  chemically  1  grm.  0;  while,  according  to  Hoppe-Seyler,  the  pro- 
portion is  1  atom  iron  to  2  atoms  0, 

When  blood  is  kept  long  outside  of  the  blood-vessels,  the  quantity  of  O  gradually 
diminishes,  and  if  it  be  kept  for  a  length  of  time  at  a  high  temperature  it  may 
disappear  altogether.  This  depends  upon  decomposition  occurring  within  the 
blood.  By  this  decomposition  in  the  blood  (cadaveric  phenomenon),  reducing 
substances  are  formed  which  consume  the  0.  All  kinds  of  blood,  however,  do  not 
act  with  equal  energy  in  consuming  0,  e.g.,  venous  blood  from  active  muscles  acts 
most  energetically,  while  that  from  the  hepatic  vein  has  very  little  effect.  CO2 
appears  in  the  blood  in  place  of  the  0,  and  the  colour  darkens.  The  amount  of 
CO2  produced  is  sometimes  greater  than  that  of  the  0  consumed. 


•the  blood-gases,  57 

If  blood  (or  a  solution  of  oxyhaimoglobin)  be  acted  upon  by  adds  (e.r/.,  tartaric 
acid)  until  it  is  strongly  acid,  O  may  be  pumped  out  in  considerably  less  amount, 
while  the  formation  of  COo  is  not  increased.  We  must,  therefore,  assume  that, 
during  the  decomposition  of  the  Hb  caused  by  the  acids  (p.  33),  a  decomposition 
product  becomes  more  highly  oxidised  by  the  iutense  chemical  union  of  the  0  at 
the  moment  of  its  origin  (Lothar  Meyer,  Zuntz,  Strassburg).  The  same  phe- 
nomenon occurs  ■when  oxyhcemoglobin  is  decomposed  by  hoU'uHj. 


37.  Is  Ozone  (O3)  Present  in  Blood? 

On  account  of  the  numerous  and  energetic  oxidations  whicli  occur 
in  connection  with  the  blood,  the  question  has  often  been  raised  as  to 
whether  the  0  of  the  blood  exists  in  the  form  of  active  0  (0^),  or 
ozone.  Ozone,  however,  is  contained  neither  in  the  blood  itself 
(Schonbein)  nor  in  the  blood-gases  obtained  from  it.  Nevertheless, 
the  red  corpuscles  (and  Hb)  have  a  distinct  relation  to  ozone. 

(1.)  Tests  for  Ozone. — Haemoglobin  acts  as  a  conveyer  of  ozone,  i.e.,  it  is  able  to 
remove  the  active  0  of  other  bodies  and  to  convey  or  transfer  it  at  once  to  other 
easily  oxidisable  substances.  («.)  Turpentine  which  has  been  exposed  to  the  air 
for  a  long  time  always  contains  ozone.  The  tests  for  the  latter  are  starch  and 
potassium  iodide,  the  ozone  decomposing  the  iodide  when  the  iodine  strikes  a  blue 
with  the  starch,  [b.)  Freshly-prepared  tincture  of  guaiacura  is  also  rendered  blue 
by  ozone.  If  some  tincture  of  guaiacum  be  added  to  turpentine  there  is  no  reaction, 
but  on  adding  a  drop  of  blood  a  deep  blue  colour  is  immediately  produced,  i.e., 
blood  takes  the  ozone  from  the  turpentine  and  conveys  it  at  once  to  tlie  dissolved 
guaiacum,  which  becomes  blue  (Schonbein,  His).  It  is  innnaterial  whether  the 
Hb  contains  0  or  not. 

(2.)  It  has  been  asserted  also  that  hseraoglobin  acts  as  an  o.:one- 
producer,  i.e.,  that  it  can  convert  the  ordinary  0  of  the  air  into  ozone. 
Hence  the  reason  why  red  blood-corpuscles  alone  render  guaiacum 
blue.  This  reaction  succeeds  best  when  the  guaiacum  solution  is 
allowed  to  dry  on  blotting-paper,  and  a  few  drops  of  blood  (diluted 
5  to  10  times)  are  poured  on  it.  That  the  Hb  forms  ozone  from  the 
surrounding  0,  is  shown  by  the  experiment  in  which  even  red  blood- 
corpuscles  containing  carbonic  oxide  were  found  to  cause  the  blue 
colour  (Kiilme  and  Scholz). 

According  to  Pfliiger,  however,  these  reactions  only  occur  from 
decomposition  of  the  Hb,  and  as  a  result  of  this  view  the  blood- 
corpuscles  cannot  be  regarded  as  producers  of  ozone. 

Sulphuretted  hydrogen  is  decomposed  by  blood  (as  by  ozone  itself)  Into  sulphur 
and  water.  Hydric  peroxide  is  decomposed  by  blood  into  0  and  water  [but  this 
reaction  is  prevented  by  the  addition  of  a  small  amount  of  hydrocyanic  acid 
(Schonbein)].  Crystallised  Hb  does  not  do  this,  and  H0O2  may  be  cautiously 
injected  into  the  blood-vessels  of  animals.  This  would  show  tiiat  nnchanrjed  Hb 
does  not  produce  ozone. 

Various  Forms  of  Oxygen.— There  are  three  forms   of  oxygen:    (1.)    The 


58  CARBONIC  ACID   AND   NITROGEN   IN  BLOOD. 

ordinary  oxygen  (O2)  in  the  air.  (2.)  Active  or  nascent  oxygen  (0),  which  never 
can  occur  iu  the  free  state,  but  the  moment  it  is  formed  acts  as  a  powerful 
oxidising  agent  and  produces  chemical  compounds.  It  converts  water  into  hydric 
peroxide — the  N  of  the  air  into  nitrous  and  nitric  acids,  and  even  CO  into  CO2, 
which  ozone  does  not.  It  certainly  plays  an  important  part  in  the  organism.  (3.) 
Ozone  (O3),  which  is  formed  by  the  decomposition  of  several  molecules  of  ordinary 
oxygen  (O2)  into  two  atoms  of  0,  and  the  appropriation  of  each  of  these  atoms  by  a 
molecule  of  undecomposed  oxygen.     It  is  oxygen  condensed  to  §  of  its  volume. 


38.  Carbonic  Acid  and  Nitrogen  in  Blood. 

II.  Carbonic  Acid. — In  arterial  blood  there  are  about  30  volumes  per 
cent,  of  CO2  (at  0°C.  and  1  metre  pressure — Setschenow);  but  in  venous 
blood  the  amount  is  very  variable ;  e.g.,  in  the  venous  blood  of  passive 
muscles  there  are  35  volumes  per  cent.  (Sczelkow),  while  in  the  blood 
of  asphyxia  there  may  be  5 2 "6  volumes  per  cent.  The  amount  of  COg 
in  the  lymph  of  asphyxia  is  less  than  that  in  the  blood  (Buchner, 
Gaule). 

The  COg  in  the  entire  mass  of  the  blood  may  be  extracted  from  it  or 
completely  pumped  out,  but  during  the  process  of  evacuation,  or  removal 
of  the  gas,  a  new  property  of  the  red  blood-corpuscles  is  produced, 
whereby  they  assume  the  function  of  an  acid  and  thus  aid  in  the  chemical 
expulsion  of  the  CO^.  This  acid-like  property  of  the  red  corpuscles 
occurs  especially  in  the  j)resence  of  0  and  heat. 

(A.)  The  CO2  in  the  Plasma. — The  largest  portion  of  the  CO^  belongs  to 
the  plasma  (or  serum)  and  it  appears  all  to  be  in  a  state  of  chemical 
combination.  Serum  takes  up  COg  quite  independently  of  pressure, 
hence  it  cannot  be  merely  absorbed.  A  certain  part  of  the  COg  can  be 
removed  from  the  serum  (plasma)  by  the  torricellian  vacuum,  while 
another  part  is  obtained  only  after  the  addition  of  an  acid.  [This  is 
called  the  "  fixed "  COo,  while  the  former  is  known  as  the  "  loose " 
CO2.] 

The  union  of  COo  in  the  serum  may  take  place  in  the  following 
ways : — 

(1.)  CO2  is  united  to  the  soda  of  the  plasma  in  the  form  of  "  sodic 
carbonate."  This  portion  of  the  CO2  can  only  be  displaced  from  its 
combination  by  the  addition  of  an  acid.  (In  depriving  blood  of  its 
gases  the  red  corpuscles  play  the  r61e  of  an  acid.) 

(2.)  A  portion  of  the  CO2  is  loosely  united  to  sodic  carbonate  in 
the  form  of  sodic  bicarbonate;  the  carbonate  takes  up  1  equivalent  of 
CO2;  NaaCOg  +  CO2  -f  H2O  =  2  NaHCOg.  This  CO2  may  be  pumped  out, 
as  in  the  process  the  bicarbonate  splits  up  again  into  the  neutral 
carbonate  and  CO.,. 


CARBONIC   ACID   AND   NITROGEN    IN   BLOOD.  59 

Preyer  has  objected  to  this  view  on  the  ground  that  blood  is  alkaline  in  reaction, 
whilst  all  solutions  that  contain  CO2  in  a  state  of  absorption,  or  loose  chemical 
combination,  are  always  acid.  Pfliiger  and  Zuntz  showed  that  blood,  after  being 
completely  saturated  with  COo,  still  remains  alkaline. 

As  the  bicarbonate  only  gives  up  its  CO2  very  slowly  in  vacuo,  while  blood  gives 
off  its  CO2  very  energetically,  perhaps  the  soda,  united  with  an  albuminous  body, 
combines  with  the  CO2  and  forms  a  complex  compound,  from  which  the  CO2  is 
rapidly  given  off  in  vacuo. 

(3.)  A  minimal  portion  of  the  CO2  may  be  chemically  united  in  the 
plasma  with  neutral  sodic  i)liosphate  (Fernet).  One  equivalent  of  this 
salt  can  fix  1  equivalent  of  CO2,  so  add  sodium  phosphate  and  acid 
sodium  carbonate  are  formed,  NaallPO^  +  CO^  +  H^^O  =  NaH^PO^ 
+  NaH,C03  (Hermann).  When  the  gases  are  removed  the  COr, 
escapes,  and  neutral  sodic  phosphate  remains. 

It  is  probable,  however,  that  almost  all  the  sodic  phosphate  found  in  the  blood- 
ash  arises  from  the  burning  of  lecithin;  we  have,  therefore,  to  consider  only  the 
very  small  amount  of  this  salt  which  occurs  in  the  plasma  (Hoppe-Seyler  and 
Sertoli). 

(B.)  The  COo  in  the  Blood-Corpuscles. — The  red  corpuscles  contain 
CO2  in  a  loose  chemical  combination;  for  (1.)  a  volume  of  blood  can 
fix  nearly  as  much  CO.,  as  an  equal  volume  of  «erum  (Ludwig,  Al. 
Schmidt);  and  (2.)  witli  increasing  pressure  the  absorption  of  COg  by 
blood  takes  place  in  a  ilifferent  ratio  from  what  occurs  with  serum 
(Pfluger,  Zuntz).  The  red  corpuscles  may  fix  more  CO^  than  their 
own  volume,  and  the  union  of  the  COg  seems  to  depend  upon  the  Hb, 
for  Setschenow  found  that,  when  Hb  was  acted  on  by  CO2,  its  power 
of  fixing  the  latter  was  increased,  Avhich  is  perhaps  due  to  the  forma- 
tion of  some  substance  (paraglobulin)  more  suited  for  fixing  COg. 
The  colourless  corpuscles  also  fix  CO.,  after  the  manner  of  the  serum- 
constituents,  and  to  the  extent  of  to  yV  of  the  absorbing  power  of 
serum  (Setschenow). 

in.  Nitrogen  exists  in  the  blood  to  the  extent  of  1*4  to  1*6  vol. 
per  cent.,  and  it  appears  to  be  simply  ahsorhed. 

It  is  still  doubtful  whether  a  small  part  of  the  N  exists  chemically  united  in  the 
red  corpuscles.  Outside  the  body  when  blood  is  heated,  and  when  there  is  a  free 
supply  of  0  and  warmth,  it  gives  off  very  minute  quantities  of  ammonia,  which 
are  perhaps  derived  from  the  decomposition  of  some  salt  of  ammonia  as  yet  unknown 
(Kiihne  and  Strauch). 

39.  Arterial  and  Venous  Blood. 

Arterial  blood  contains  in  solution  all  those  substances  which  are 
necessary  for  the  nutrition  of  the  tissues,  those  which  are  employed  in 
secretion ;   it  also  contains  a  rich  supply  of  0.     Venous  blood  must 


more 

0, 

less  COg, 

more 

water, 

more 

fibrin, 

more 

extractives 

more 

salts. 

60  ARTERIAL  AND   VENOUS   BLOOD. 

contain  less  of  all  these,  but  in  addition  it  holds  the  used-up  or  effete 
substances  derived  from  the  tissues,  and  the  products  of  their  retro- 
gressive metabolism  being  more  numerous,  there  is  in  venous  blood  a 
larger  amount  of  COg.  It  is  evident  also  that  the  blood  of  certain 
veins  must  have  special  characters,  e.g.,  that  of  the  portal  and 
hepatic  veins. 

The  following  are  the  most  important  points  of  difference  between 
arterial  and  venous  blood  : — 

Arterial  Blood,  contains— 

more  sugar, 

fewer  blood-corpuscles, 

less  urea. 

It    is   bright    red    and   not 

dichroic. 
As  a  rule  it  is  1°C.  warmer. 

The  hriglit  red  colour  of  arterial  blood  depends  on  the  presence  of 
oxyhaemoglobin,  whilst  the  dark  colour  of  venous  blood  is  due  to  its 
smaller  proportion  of  oxyhsemoglobin,  and  the  quantity  of  reduced 
haemoglobin  which  it  contains.  The  dark  change  of  colour  is  not  to 
be  attributed  to  the  larger  quantity  of  COg  in  venous  blood  (Marchand); 
for  if  equal  qualities  of  0  be  added  to  two  portions  of  blood,  and  if 
CO,  be  added  to  one  of  them,  the  colour  is  not  changed  (Pfliiger). 

40.  auantity  of  Blood. 

In  the  adult  the  quantity  of  blood  is  equal  to  jV  P^-i-'t  of  the  body- 
weight  (Bischoff),  in  newly-born  children  yV  (Welcker). 

According  to  Schlicking,  the  amount  of  blood  in  a  newly-born  child  depends  to 
some  extent  upon  the  time  at  which  the  umbilical  cord  is  ligatured.  The  amount 
=  tV  of  the  body- weight  when  the  cord  is  tied  at  once,  while  if  it  is  tied  some- 
what later  it  may  be  I.  Immediate  ligature  of  the  cord  may,  therefore,  deprive 
a  newly-born  child  of  100  grammes  of  blood.  Further,  the  number  of  corpuscles 
is  less  in  a  child  after  immediate  ligature  of  the  umbilical  cord,  than  when  it  ia 
tied  somewhat  later  (Helot). 

Various  methods  are  adopted  to  ascertain  the  amount  of  blood,  but 
perhaps  that  of  Welcker  is  the  best. 

The  methods  of  Valentin  (1838),  and  Ed.  Weber  (1850),  are  not  now  used,  as 
the  results  obtained  are  not  sufficiently  accurate. 

Method  of  Welcker  (1854).— Begin  by  taking  the  weight  of  the  animal  to  be 
experimented  on  ;  place  a  cannula  in  the  carotid,  and  allow  the  blood  to  run 
into  a  flask  previously  weighed,  and  in  which  small  pebbles  (or  Hg)  have  been 
placed  in  order  to  detibrinate  the  blood  by  shaking.  Take  a  part  of  this  delibrin- 
ated  blood,  and  make  it  cherry-red  in  colour  by  passing  through  it  a  stream  of  CO 


NORMAL   QUANTITY   OF   BLOOD.  61 

(because  ordinary  blood  varies  in  colour  according  to  the  amount  of  0  contained  iu 
it — Gscheidlen,  Heidenhain).  Tie  a  I—  -shaped  cannula  in  the  two  cut  ends  of  the 
carotid,  and  allow  a  0"6  per  cent,  solution  of  common  salt  to  How  into  the  vessel 
from  a  pressure  bottle  ;  collect  the  coloured  fluid  issuing  from  the  jugular  veins 
and  inferior  vena  cava  until  the  fluid  is  quite  clear.  The  entire  body  is  then 
chopped  up  (with  the  exception  of  the  contents  of  the  stomach  and  intestines, 
which  are  Aveighed,  and  their  weight  deducted  from  the  body-weight),  and 
extracted  with  water,  and  after  twenty-four  hours  the  fluid  is  expressed.  This 
water,  as  well  as  the  washings  with  salt  solution,  are  collected  and  weighed,  and 
part  of  the  mixture  is  saturated  with  CO.  A  sample  of  this  dilute  blood  is  placed 
in  a  vessel  with  parallel  sides  (1  cm.  thick),  opposite  the  light  (the  so-called 
hsematinoraeter) ,  and  in  a  second  vessel  of  the  same  dimensions,  a  sample  of  the 
undiluted  CO-blood  is  diluted  with  water  from  a  burette  until  both  fluids  give 
the  sajne  intensity  of  colour.  From  the  quantity  of  water  required  to  dilute  the 
blood  to  the  tint  of  the  washings  of  the  blood-vessels,  the  quantity  of  blood  in 
the  washings  is  calculated,  (On  chopping  up  the  muscles  alone,  we  obtain  the 
amount  of  Hb  present  in  them,  which  is  not  taken  into  calculation— Kiihne). 

ftuantity  of  Blood  in  Various  Animals. — The  quantity  of  blood  in 
the  mouse  =  jV  to  ^^-j  guinea-pig  -J..-  (jV  to  ^y ;  rabbit  =  ^^ 
(t5  to  h)  '>  dog  =  tV  (tt  to  tV)  i  cat  r=  ^ ;  birds  =  ^V  to  ^^ ; 
frog  =  jV  to  ^ ;  fishes  =  -^^  to  ^V  of  the  body-weight  (without  the 
contents  of  the  stomach  and  intestines). 

The  specific  gravity  of  the  blood  ought  always  to  be  taken  when 
estimating  the  amount  of  blood.  The  amount  of  blood  is  diminished 
during  inanition ;  fat  persons  have  relatively  less  blood ;  after  haemorr- 
hage the  loss  is  at  first  replaced  by  a  watery  fluid,  while  the  blood- 
corpuscles  are  gradually  regenerated  (p.  63). 

The  estimation  of  the  quantity  of  blood  iu  different  organs  is  done  by 
suddenly  ligaturing  their  blood-vessels  intra  vitam.  A  watery  extract 
of  the  chopped  up  organ  is  prepared,  and  the  quantity  of  blood  estimated 
as  described  above.  Roughly,  it  may  be  said  that  the  lungs,  heart,  large 
arteries,  and  veins  contain  ^ ;  the  muscles  of  the  skeleton,  \ ;  the 
liver,  \  ■.  and  other  organs,  \  (Ranke). 


41.  Variations  from  the  Normal  Condition  of 
the  Blood. 

(A.)  Increase  of  the  Blood,  or  of  its  Individual  Constituents.— (l)  An 

increase  in  the  entire  mass  of  the  blood,  uniformly  in  all  orijans,  constitutes 
polycemia  (or  plethora),  and  in  over-nourished  individuals  it  may  approach  a  patho- 
logical condition.  A  bluish-red  colour  of  the  skin,  swollen  veins,  large  arteries, 
hard  full  pulse,  injection  of  the  capillaries  and  smaller  vessels  of  the  visible 
mucous  membranes  are  signs  of  this  state,  accompanied  by  congestion  of  the  brain, 
giving  rise  to  vertigo,  and  congestion  of  the  lungs,  as  shown  by  breathlessness. 
After  major  amputations  with  little  loss  of  blood  a  relative  increase  of  blood  has 
been  found  (?)  (plethora  apocoptica). 

Transfusion.— Polyaemia  may  be  produced  artificially  by  the  injection  of  blood 
of  the  same  species.     If  the  normal  quantity  of  blood  be  increased  83  per  cent. 


62  TRANSFUSION    OF   BLOOD. 

no  abnormal  condition  occurs,  because  the  blood-pressure  is  not  permanently 
raised.  The  excess  of  blood  is  accommodated  in  the  greatly  distended  capillaries, 
which  may  be  stretched  beyond  their  normal  elasticity  (Worm  Miiller).  If  it  be 
increased  to  150  per  cent,  there  are  variations  in  the  blood-pressure,  life  is 
endangered,  and  there  may  be  sudden  rupture  of  blood-vessels  (Worm  Miiller). 

Fate  of  Transfused  Blood. — After  the  transfusion  of  blood  the  formation  of 
lymph  is  greatly  increased ;  but  in  one  to  two  days  the  serum  is  used  up,  the 
water  is  excreted  chiefly  by  the  urine,  and  the  albumin  is  partly  changed  into 
urea  (Landois).  Hence,  the  blood  at  this  time  appears  to  be  relatively  richer  in 
blood-corpuscles  (Panum,  Lesser,  Worm  Miiller).  The  red  corpuscles  break  up 
much  more  slowly,  and  the  products  thereof  are  partly  excreted  as  urea  and  j)artly 
(but  not  constantly)  as  bile  pigments.  Even  after  a  month  an  increase  of 
coloured  blood-corpuscles  has  been  observed  (Tschirjew).  That  the  blood-cor- 
puscles are  broken  up  slowly  in  the  economy  is  proved  by  the  fact  that  the  amount 
of  urea  is  much  larger  when  the  same  quantity  of  blood  is  swallowed  by  the 
animal,  than  when  an  equal  amount  is  transfused  (Tschirjew,  Landois).  In  the 
latter  case  there  is  a  moderate  increase  of  the  urea  lasting  for  days,  a  proof  of 
the  slow  decomposition  of  the  red  corpuscles.  Pronounced  over-filling  of  the 
vessels  causes  loss  of  appetite,  and  a  tendency  to  hsemorrhage  of  the  mucous 
membranes. 

(2.)  PolySBmia  serosa  is  that  condition  in  which  the  amount  of  serum — i.e., 
the  amount  of  water  in  the  blood,  is  increased.  This  may  be  produced  artificially 
by  the  transfusion  of  blood-serum  from  the  same  species.  The  water  is  soon  given 
off  in  the  urine,  and  the  albumin  is  decomposed  into  urea,  without  however,  pass- 
ing into  the  urine.  An  animal  forms  more  urea  in  a  short  time  from  a  quantity  of 
transfused  serum  than  from  the  same  quantity  of  blood,  a  proof  that  the  blood- 
corpuscles  remain  longer  undecomposed  than  the  serum  (Forster,  Landois).  If 
serum  from  another  species  of  animal  be  used  {e.g.,  dog's  serum  transfused  into  a 
rabbit),  the  blood-corpuscles  of  the  recipient  are  dissolved ;  hsemoglobinuria  is 
produced  (Ponfick) ;  and  if  there  be  general  dissolution  of  the  corpuscles,  death 
may  occur  (Landois). 

Folysemia  aquosa  is  a  simple  increase  of  the  water  of  the  blood,  and  occurs 
temporarily  after  copious  drinking,  but  increased  diuresis  soon  restores  the  normal 
condition.  Diseases  of  the  kidneys,  which  destroy  their  secreting  parenchyma, 
produce  this  condition,  and  often  general  dropsy,  owing  to  the  passage  of  water 
into  the  tissues.  Ligature  of  the  ureter  produces  a  watery  condition  of  the 
blood. 

(3.)  Plethora  polycythsemica,  Hyperglobulie.— An  increase  of  the  red  cor- 
puscles has  been  assumed  to  occur  Avhen  customary  regular  haemorrhages  are  inter- 
rupted— e.^.,  menstruation,  bleeding  from  the  nose,  &c. ;  but  the  increase  of  corpuscles 
has  not  been  definitely  proved.  There  is  a  proved  case  of  temporary  polycythsemia — 
viz.,  when  similar  blood  is  transfused,  a  part  of  the  fluid  is  used  up,  while  the 
corpuscles  remain  unchanged  for  a  considerable  time.  There  is  a  remarkable  increase 
in  the  number  of  blood-corpuscles  (to  8 '82  millions  per  cubic  millimetre,  p.  4)  in 
certain  severe  cardiac  affections  where  there  is  great  congestion,  and  much  water 
transudes  through  the  vessels.  In  cases  of  hemiplegia,  for  the  same  reason,  the 
number  of  corpuscles  is  greater  on  the  paralysed  congested  side  (Penzoldt).  After 
diarrhoea,  which  diminishes  the  water  of  the  blood,  there  is  also  an  increase 
(Brouardel).  There  is  a  temporary  increase  in  the  hcumatoUasts  as  a  reparative 
process  after  severe  haemorrhage  (p.  15),  or  after  acute  diseases.  In  cachectic 
conditions  this  increase  continues,  owing  to  the  diminished  non-conversion  of  these 
corpuscles  into  red  corpuscles.  In  the  last  stages  of  cachexia  the  number 
diminishes  more  and  more  until  the  formation  of  hsematoblasts  ceases  (Hayem), 

(4.)  Plethora  hyperalbuminosa  is  a  term  applied  to  the  increase  of  albumins  in 
the  plasma,  such  as  occurs  after  taking  a  large  amount  of  food.     A  similar  con- 


ABNORMAIi   CONDITIONS   OF  TI[E    TU.OOD.  63 

dition  is  pioducecl  by  transfusing  the  serum  of  the  same  species,  whereby,  at  the 
same  time,  the  urea  is  increased.  Injection  of  egg-albumin  produces  albuminuria 
(Stokes,  Lehmann). 

(B.)  Diminution  of  the  Quantity  of  Blood,  or  its  Individual  Consti- 
tuents.— (1.)  Oligsemia  vera,  or  diminution  of  the  quantity  of  blood  as  a  whole, 
occurs  whenever  there  is  htemorrhage.  Life  is  endangered  in  newly -born  children 
when  they  lose  a  few  ounces  of  blood;  in  children  a  year  old,  on  losing  half-a-pound  ; 
and  in  adults,  when  one-half  of  the  total  blood  is  lost.  Women  bear  loss  of  blood 
much  better  than  men.  The  periodical  formation  of  blood  after  each  menstruation 
seems  to  enable  blood  to  by  renewed  more  rapidly  in  their  case.  .Stout  persons, 
old  people,  and  children  do  not  bear  the  loss  of  blood  well.  The  more  rapidly 
blood  is  lost,  the  more  dangerous  it  is. 

Symptoms  of  Loss  of  Blood.— Great  loss  of  blood  is  accompanied  by  general 
paleness  and  coldness  of  the  cutaneous  surface,  increased  oppression,  twitching  of 
the  eyeballs,  noises  in  the  ears  and  vertigo,  loss  of  voice,  great  breathlessness, 
stoppage  of  secretions,  coma  ;  dilatation  of  the  pupils,  involuntary  evacuations  of 
urine  and  fseces,  and  lastly,  general  convidsions,  are  sure  signs  of  death  hy 
hcemorrhage.  In  the  gravest  cases  restitution  is  only  possible  by  means  of  trans- 
fusion. Animals  can  bear  the  loss  of  one-foiirth  of  their  entire  blood  without  the 
blood-pressure  in  the  arteries  permanently  falling,  because  the  blood-vessels  con- 
tract and  accommodate  themselves  to  the  smaller  quantity  of  blood  (in  consequence 
of  the  stimulation  of  the  vasomotor  centre  in  the  medulla).  The  loss  of  one-third 
of  the  total  blood  diminishes  the  blood-pressure  considerably  (one-fourth  in  the 
carotid  of  the  dog).  If  the  hemorrhage  is  not  such  as  to  cause  death,  the  fluid 
part  of  the  blood  and  the  dissolved  salts  are  restored  by  absorption  from  the 
tissues,  the  blood-pressure  gradually  rises,  and  then  the  albumin  is  restored, 
though  a  longer  time  is  required  for  the  formation  of  red  corpuscles.  At  first, 
therefore,  the  blood  is  abnormally  rich  in  water  (hydrcemla),  and  at  last  abnormally 
poor  in  corpuscles  {oligocytluemid,  hypoglohulie) .  With  the  increased  lymph- 
stream  which  pours  into  the  blood,  the  colourless  corpuscles  are  considerably 
increased  above  normal,  and  during  the  period  of  restitution  fewer  red  corpuscles 
seem  to  be  used  up  {<'.y.,  for  bile). 

After  moderate  bleeding  from  an  artery  in  animals,  Buntzen  observed  that  the 
volume  of  the  lilood  was  restored  in  several  hours;  after  more  severe  hremorrhage 
in  24  to  48  hours.  The  red  blood-corpuscles  after  a  loss  of  blood  equal  to 
1"1  to  4*4  per  cent,  of  the  body-weight,  are  restored  only  after  7  to  34  days. 
The  generation  begins  after  24  hours.  During  the  period  of  regeneration  the 
number  of  the  smallest  blood-corpuscles  (hremato-blasts)  is  increased.  Even  in 
man  the  duration  of  the  period  of  regeneration  depends  upon  the  amount  of  blood 
lost  (Lyon).  The  amount  of  hajmoglobin  is  diminished  nearly  in  proportion  to 
the  amount  of  the  haemorrhage  (Bizzozero  and  Salvioli). 

Metabolism  in  AnSBmia- — The  condition  of  the  metaboll'^m  within  the  bodies  of 
anaemic  persons  is  important.  The  decomposition  of  proteids  is  increased  (the 
same  is  the  case  in  hunger),  hence  the  excretion  of  urea  is  increased  (Bauer, 
Jlirgensen).  The  decomposition  of  fats,  on  the  contrary,  is  diminished,  which 
stands  in  relation  with  the  diminution  of  CO2  given  off.  Antemic  and  chlorotic 
persons  put  on  fat  easily.  The  fattening  of  cattle  is  aided  by  occasional  bleedings 
and  by  intercurrent  periods  of  hunger  (Aristotle). 

(2.)  An  excessive  thickening  of  the  blood  through  loss  of  water  is  called 
Oligsemia  sicca.  This  occurs  in  man  after  copious  watery  evacuations,  as  in 
cholera,  so  that  the  thick  tarry  blood  stagnates  in  the  vessels.  Perhaps  a  similar 
condition — though  to  a  less  degree— may  exist  after  very  copious  perspiration. 

(3.)  If  the  proteids  in  blood  be  abnormally  diminished  the  condition  is  called 
Oligaemia  hypalbuminosa ;  they  may  be  diminished  about  one-half.  They 
are  usually  replaced  by  an  excess  of  water  in  the  blood.    Loss  of  albumin  from 


64:  ABNORMAL    CONDITIONS    OF   THE   BLOOD. 

the  blood  is  caused  directly  by  albuminuria  (25  grammes  of  albumin  may  be  given  off 
by  the  urine  daily),  persistent  suppuration,  great  loss  of  milk,  extensive  cutaneous 
ulceration,  albuminous  diarrhea  (dysentery).  Frequent  and  copious  haemorrhages, 
however,  by  increasing  the  absorption  of  water  into  the  vessels,  at  first  produce 
oliggemia  hypalbuminosa. 

Mellitsemia. — The  sugar  in  the  blood  is  partly  given  off  by  the  urine,  and  in 
"diabetes  mellitus  "  one  kilo.  (2*2  lbs.)  may  be  given  off  daily,  when  the  quantity 
of  urine  may  rise  to  25  kilos.  To  replace  this  loss  a  large  amount  of  food  and 
drink  is  required,  whereby  the  urea  may  be  increased  threefold.  The  increased 
production  of  sugar  causes  an  increased  decomposition  of  albuminous  tissues;  hence 
the  urea  is  always  increased,  even  though  the  supply  of  albumin  be  insufficient. 
The  patient  loses  flesh  ;  all  the  glands,  and  even  the  testicles,  atrophy  or  degenerate 
(pulmonary  phthisis  is  common) ;  the  skin  and  bones  become  thinner ;  the 
nervous  system  holds  out  longest.  The  teeth  become  carious  on  account  of  the  acid 
saliva,  the  crystalline  lens  becomes  turbid  from  the  amount  of  sugar  in  the  fluid 
of  the  eye  which  extracts  water  fi-om  the  lens  (Kunde,  Heubel),  and  wounds  heal 
badly  because  of  the  abnormal  condition  of  the  blood.  Absence  of  all  carbo- 
hydrates in  the  food  causes  a  diminution  of  the  sugar  in  the  blood,  but  does  not 
cause  it  to  disappear  entirely.  An  excessive  amount  of  inosite  has  been  found  in  the 
blood  and  urine,  constituting  mellituria  inosita  (Vohl). 

Lipsemia,  or  an  Increase  of  the  Fat  in  the  Blood,  occurs  after  every  meal 

rich  in  fat,  so  that  the  serum  may  become  turbid  like  milk.  Pathologically,  this 
occurs  in  a  high  degree  in  drunkards  and  in  corpulent  individuals.  When  there  is 
great  decomposition  of  albumin  in  the  body  (and  therefore  in  very  severe  diseases), 
the  fat  in  the  blood  increases,  and  this  also  takes  place  after  a  liberal  supply  of 
easily  decomposable  carbo-hydrates  and  much  fat. 

The  Salts  remain  very  persistently  in  the  blood.  The  withdrawal  of  common 
salt  produces  albuminuria,  and,  if  all  salts  be  withheld,  paralytic  phenomena  occur 
(Forster).  Over-feeding  with  salted  food,  such  as  salt  meat,  has  caused  death 
through  fatty  degeneration  of  the  tissues,  especially  of  the  glands.  Withdrawal  of 
lime  and  phosphoric  acid  produces  atrophy  and  softening  of  the  bones.  In  infectious 
diseases  and  dropsies  the  salts  of  the  blood  are  often  increased,  and  diminished  in 
inflammation  and  cholera.  [NaCl  is  absent  from  the  urine  in  certain  stages  of 
pneumonia,  and  it  is  a  good  sign  when  the  chlorides  begin  to  return  to  the 
urine]. 

The  amount  of  fihrin  is  increased  in  inflammations  of  the  lung  and  pleura; 
hence,  such  blood  forms  a  crusta  phloyistica  (p.  39).  In  other  diseases,  where 
decomposition  of  the  blood-corpuscles  occurs,  the  fibrin  is  increased,  perhaps 
because  the  dissolved  red  corpuscles  yield  material  for  the  formation  of  fibrin. 
After  repeated  haemorrhages,  Sigm.  Mayer  found  an  increase  of  fibrin.  Blood  rich 
in  fibrin  is  said  to  coagulate  more  slov)ly  than  when  less  fibrin  is  present — still 
there  are  many  exceptions. 

For  the  abnormal  changes  of  the  red  and  white  blood-corpuscles  see  p.  23. 


Physiology  of  the  Circulation. 


42.  General  View  of  the  Circulation. 

The  blood  within  the  vessels  is  in  a  state  of  continual  motion,  being 

carried   from   the    ventricles    by   the   large 

arteries   (aorta  and   pulmonary)   and    their 

branches   to  the  system  of  cainllary  vessels, 

from  which  again,  it  passes  into  the   veins 

that  end  in  the  atria  of  the   auricles  (W. 

Harvey). 

The  cause  of  the  circulation  is  the  differ- 
ence of  pressure  which  exists  between  the 
blood  in  the  aorta  and  pulmonary  artery  on 
the  one  hand,  and  the  two  ven^  cavse  and 
the  four  pulmonary  veins  on  the  other. 
The  blood,  of  course,  moves  continually  in 
its  closed  tubular  system  in  the  direction  of 
least  resistance.  The  greater  the  difference 
of  pressure,  the  more  rapid  the  movement 
will  be.  The  cessation  of  the  difference  of 
pressure  (as  after  death)  naturally  brings  the 
movement  to  a  standstill.  The  circiilation 
is  usually  divided  into — 

(1.)  The  greater,  or  systemic  circulation, 
which  includes  the  course  of  the  blood  from 
the  left  auricle  and  left  ventricle,  through  the 
aorta  and  all  its  branches,  the  capillaries  of  Scheme  of  the  circulation— a, 
the  body  and  the  veins,  until  the  two  vena?      right  auricle ;  A,  right  ven 
cavse  terminate  in  the  right  auricle. 

(2.)  The  lesser,  or  pulmonic  circulation, 
which  includes  the  course  from  the  right 
auricle  and  right  ventricle,  the  pulmonary 
artery,  the  pulmonary  capillaries,  and  the 
four  pulmonary  veins  springing  from  them, 
until  these  open  into  the  right  auricle. 

(3.)  The  portal  circulation,  which  is  some- 
times spoken  of  as  a  special  circulatory  system, 
although  it  represents  only  a  second  set  of 

capillaries  (within  the  liver)  introduced  into  the  course  of  a   venous 

5 


Ym.  IG. 


tricle ;  h,  left  auricle ;  B, 
left  ventricle ;  1,  pulmonary 
artery  ;  2,  aorta  with  semi- 
lunar valves  ;  I,  area  of  pul- 
monary circulation ;  K,area 
of  systemic  circulation  in 
region  supplying  the  supe- 
rior vena  cava,  o;  G,  area 
supplying  the  inferior  vena 
cava,  u;  d,  d,  intestine;  m, 
mesenteric  artery;  q,  portal 
vein  ;  L,  liver ;  h,  hepatic 
vein. 


66 


MUSCULAR  FIBRES   OF  THE   HEART. 


trunk.  It  consists  of  the  vena  portarum — formed  by  the  union  of  the 
intestinal  or  mesenteric  and  splenic  veins,  and  it  passes  into  the 
liver,  where  it  divides  into  capillaries,  from  which  the  hepatic  veins 
arise.    These  last  veins  join  the  inferior  vena  cava. 

Strictly  speaking,  however,  there  is  no  special  portal  circulation. 
Similar  arrangements  occur  in  other  animals  in  different  places 
— e.g.,  snakes  have  such  a  system  in  their  supra-renal  capsules,  and  the 
frog  in  its  kidneys. 

When  an  artery  splits  up  into  fine  branches  during  its  course,  and 
these  branches  do  not  form  capillaries,  but  reunite  into  an  arterial 
trunk,  a  reta  miraUle  is  formed,  such  as  occurs  in  apes  and  the  eden- 
tata.  Similar  arrangements  may  exist  on  veins,  giving  rise  to  venous 
retia  miraUIia. 


43.  The  Heart. 

Muscular  Fibres  of  the  Heart. — The  musculature  of  the  mammalian 
heart  consists  of  short  (50  to  70  fx,  man),  very  fine,  transversely  striated 
musciilar  fibres,  which  are  actual  uni-cellular  elements  (Eberth),  devoid 
of  a  sarcolemma  (15  to  25  /n  broad),  and  usually  divided  at  their 
blunt  ends,  by  which  means  they  anastomose  and  form  a  net- 
work.    (Fig.  17,  A,  B.)     The  individual  muscle-cells  contain  in  their 


Fig.  17. 

A,  branched  muscular  fibres  from  the  heart  of  a  mammal ;  B,  transverse  section  of 
the  cardiac  fibres  ;  b,  connective  tissue  corpuscles  ;  c,  capillaries  ;  C,  muscular 
fibres  from  the  heart  of  a  frog. 

centre  an  oval  nucleus,  and  are  held  together  by  a  cement  which  is 
blackened  by  silver  nitrate,  and  dissolved  by  a  33  per  cent,  solution  of 
caustic  potash.  This  cement  is  also  dissolved  by  a  40  per  cent,  solu- 
tion of  nitric  acid.  The  transverse  striae  are  not  very  distinct,  and 
not  unfrequently  there  is  an  appearance  of  longitudinal  striation,  pro- 
duced by  a  number  of  very  small  granules  arranged  in  rows  within 


ARRANGEMENT   OF  THE   CARDIAC   SIUSCULAR   FIBRES.  67 

the  fibres.  The  fibres  are  gathered  lengthwise  in  bundles,  or  fasciculi, 
surrounded  and  separated  from  each  other  by  delicate  processes  of  the 
perimysium.  "When  the  connective  tissue  is  dissolved  by  prolonged 
boiling,  these  bundles  can  be  isolated,  and  constitute  the  so-called 
"  fibres "  of  the  heart.  The  transverse  sections  of  the  bundles  in 
the  auricles  are  polygonal  or  rounded,  while  in  the  ventricles  they 
are  somewhat  flattened.  [The  muscular  mass  of  the  heart  is  called  the 
■myocardium,  and  is  invested  by  fibrous  tissue.  It  is  important  to 
notice  that  the  connective  tissue  of  the  visceral  pericardium  (epicardium) 
is  continuous  with  that  of  the  endocardium  by  means  of  the  peri- 
mysium surrounding  the  bundles  of  muscular  fibres.]  The  fine  spaces 
which  exist  between  these  bundles  form  narrow  lacunae,  lined  with 
epithelium,  and  constituting  part  of  the  lymphatic  system  of  the  heart. 

[The  cardiac  muscular  fibres  occupy  an  intermediate  position  between  striped 
aad  plain  muscular  tibres.  Although  they  are  striped  they  are  involuntary,  not 
being  dii'ectly  under  the  influence  of  the  will,  while  they  contract  more  slowly 
than  a  voluntary  muscle  of  the  skeleton.] 

[In  the  fro<j^s  heart  the  muscular  tibres  are  in  shape  elongated  spindles,  or  fusi- 
form, in  this  respect  resembling  the  plain  muscle-cells,  but  they  are  transversely 
striped  (Fig.  17,  C).  They  are  easily  isolated  by  means  of  a  33  per  cent,  solution  of 
potash  or  dilute  alcohol  (Weissmann,  Ranvier).] 

44.  Arrangement  of  the  Cardiac  Muscular  Fibres, 
and  their  Physiological  Importance. 

The  study  of  the  embryonic  heart  is  the  key  to  a  proper  understand- 
ing of  the  complicated  arrangement  of  the  fibres  in  the  adult  heart. 
The  simple  tubular  heart  of  the  embryo  has  an  outer  circular  and  an 
iimer  longitudinal  layer  of  fibres.  The  septum  is  formed  later ;  hence, 
it  is  clear  that  a  part,  at  least,  of  the  fibres  must  be  common  to  the 
two  auricles,  and  a  part  also  to  the  two  ventricles,  since  there  is, 
originally,  but  one  chamber  in  the  heart.  The  muscular  fibres  of  the 
auricles  are,  however,  completely  separated  from  those  of  the  ventricles 
by  the  fibro-cartilaginous  rings.  In  the  auricles  the  fundamental 
arrangement  of  the  embryonic  fibres  partly  remains,  while  in  the 
ventricles  it  becomes  obscured  as  these  cavities  undergo  a  sac-Uke 
dilatation,  and  also  become  twisted  in  a  spiral  manner. 

(1.)  The  Muscular  Fibres  of  the  Auricles  are  completely  separated 
from  the  fibres  of  the  ventricles  by  the  fibrous  rings  which  surroimd 
the  auriculo-ventricular  orifices,  and  which  serve  as  an  attachment  for 
the  auriculo-ventricular  valves  (Fig.  18,  I).  The  auricles  are  much 
thinner  than  the  ventricles,  and  their  fibres  are  generally  arranged  in 
two  layers ;  the  outer  transverse  layer  is  continuous  over  both  auricles, 


68 


ARRANGEMENT  OF  THE  CARDIAC  MUSCULAR  FIBRES. 


whilst  the  inner  one  is  directed  longitudinally.  The  outer  transverse 
fibres  may  be  traced  from  the  openings  of  the  venous  trunks  anteriorly 
and  posteriorly  over  the  auricular  walls.  The  longitudinal  fibres  are 
specially  well  marked  where  they  are  inserted  into  the  fibro-cartila- 
ginous  rings,  while  in  some  parts  of  the  anterior  auricular  wall  they 
are  not  continuous.  In  the  auricular  septum,  some  fibres,  circularly 
disposed  around  the  fossa  ovalis  (formerly  the  embryonic  opening  of  the 
foramen  ovale)  are  well  marked.  Circular  hands  of  striped  muscle  exist 
around  the  veins  where  they  open  into  the  heart;  these  are  least 
marked  on  the  inferior  vena  cava,  and  are  stronger  and  reach  higher 
(2 "5  cm.)  on  the  superior  vena  cava  (Fig.  18,  II).  Similar  fibres  exist 
around  the  four  pulmonary  veins,  where  they  join  the  left  auricle,  and 
these  fibres  (which  are  arranged  as  an  inner  circular  and  an  outer 
longitudinal  layer)  can  be  traced  to  the  hilus  of  the  lung  in  man  and 
some  mammals  ;  in  the  ape  and  rat  they  extend  on  the  pulmonary  veins 
right  into  the  lung.  In  the  mouse  and  bat,  again,  the  striped  muscular 
fibres  pass  so  far  into  the  lungs  that  the  walls  of  the  smaller  veins  are 
largely  composed  of  striped  muscle  (Stieda). 


Fig.  IS. 

I.  Course  of  the  muscular  fibres  on  tlie  left  auricle — Observe  the  outer  transverse 
and  inner  longitudinal  fibres,  the  circular  fibres  on  the  pulmonary  veins  [v,  p) ; 
V,  the  left  ventricle  (John  Reid).  II.  Arrangement  of  the  striped  muscular 
fibres  on  the  superior  veca  cava  (Elischer) — a,  opening  of  vena  azygos ; 
V,  auricle. 

Circular  muscular  fibres  are  found  where  the  vena  magna  cordis 
enters  the  heart,  and  in  the  valvula  ihehesii  which  guards  it. 

From  a  X->T^ysiological  'point  of  vieiv  the  following  facts  are  to  be  noted 
as  a  result  of  the  anatomical  arrangement : — 

(l.)'The  auricles  contract  independently  of  the  ventricles.  This  is 
seen  when  the  heart  is  about  to  die ;  then  there  may  be  several 
auricular  contractions  for  one  ventricular,  and  at  last  only  the  auricles 


ARRANGEMENT   OF  THE   VENTRICULAR   FIBREF.  69 

pulsate.  The  auricular  portion  of  the  right  auricle  beats  longest ; 
hence,  it  is  called  the  "  ultimum  moriens."  Independent  rhythmical 
contractions  of  the  vense  cava3  and  pulmonary  veins  are  often  noticed 
after  the  heart  has  ceased  to  beat  (Haller,  Nysten).  [This  beating 
can  also  be  observed  in  those  veins  in  a  rabbit  after  the  heart  is  cut 
out  of  the  body.] 

(2.)  The  double  arrangement  of  the  fibres  (transverse  and  longi- 
tudinal) produces  a  simultaneous  and  uniform  diminution  of  the 
auricular  cavity  (such  as  occurs  in  most  of  the  hoUoAv  viscera). 

(3.)  The  contraction  of  the  circular  muscular  fibres  around  the 
venous  orifices,  and  the  subsequent  contraction  of  the  auricle,  cause 
these  veins  to  empty  themselves  into  the  auricle ;  and  by  their  jjresence 
and  action  they  prevent  any  large  quantity  of  blood  from  passing  back- 
ward into  the  veins  when  the  auricle  contracts.  [Xo  valves  are 
present  in  the  superior  and  inferior  vena  cava  in  the  adult  heart,  or  in 
the  pulmonary  veins,  hence  the  contraction  of  these.  Circular  muscular 
fibres  play  an  important  part  in  preventing  any  reflux  of  blood  during 
the  contraction  of  the  auricles.] 

45.  Arrangement  of  the  Ventricular  Fibres. 

(2.)  The  Muscular  Fibres  of  the  Ventricles.— The  fibres  in  the  thick 
wall  of  the  ventricles  are  arranged  in  several  layers  (Fig.  19,  A)  under  the 
pericardium.  First,  there  is  an  outer  longitudinal  layer  (A)  which  is  in 
the  form  of  single  bundles  on  the  right  ventricle,  but  forms  a  complete 
layer  on  the  left  ventricle,  where  it  measures  about  one  eighth  of 
the  thickness  of  the  ventricular  wall.  A  seco7id  longitudinal  layer  of 
fibres  lies  on  the  in7ier  surface  of  the  ventricles,  distinctly  visible  at  the 
orifices,  and  within  the  vertically  placed  papillary  muscles,  whilst 
elsewhere  it  is  replaced  by  the  irregularly  arranged  trabecule  carnese. 
Between  these  two  layers  there  lies  the  thickest  layer,  consisting  of 
more  or  less  iransversel y-arranged  bundles  which  may  be  broken  up  into 
single  layers  more  or  less  circularly  disposed.  The  deep  lymphatic 
vessels  run  between  the  layers,  whilst  the  Uood-vessels  lie  within  the 
substance  of  the  layers  and  are  surrounded  by  the  primitive  bundles 
of  muscular  fibres  (Henle).  All  tlu-ee  layers  are  not  completely 
independent  of  each  other;  on  the  contrary,  the  fibres  which  run 
obliqueli/  form  a  gradual  transition  between  the  transverse  layers  and 
the  inner  and  outer  longitudinal  layers.  It  is  not,  however,  quite 
correct  to  assume  that  the  outer  longitudinal  layer  gradually  passes 
into  the  transverse,  and  this  again  into  the  inner  longitudinal  layer 
(as  is  shown  schematically  in  C) ;  because,  as  Henle  pointed  out,  the 
transverse  fibres  are  relatively  far  greater  in  amount.     In  general,  the 


70  ARRANGEMENT   OF   THE   VENTRICULAR  FIBRES. 

A 


Fig.  19. 

Course  of  the  ventricular  muscular  fibres — A,  On  the  anterior  surface ;  B,  View 
of  the  apex  with  the  vortex  (Henle);  C,  Scheme  of  the  course  of  the 
fibres  within  the  ventricular  wall ;  D,  Fibres  passing  into  a  papillary  muscle 
(C.  L^^dwig). 

outer  longitudinal  fibres  are  so  arranged  as  to  cross  tiie  inner  longi- 
tudinal layer  at  an  acute  angle.  The  tranverse  layers  lying  between 
these  two  form  gradual  transitions  between  these  directions.  At  the 
apex  of  the  left  ventricle,  the  outer  longitudinal  fibres  bend  or  curve 
so  as  to  meet  at  the  so-called  vortex  (Wirbel)  B,  where  they  enter 
the  muscular  substance,  and,  taking  an  upward  and  inward  direction, 
reach  the  papillary  muscles,  D  (Lower) ;  although  it  is  a  mistake  to 
say  that  all  the  bundles  which  ascend  to  the  papillary  muscles  arise 
from  the  vertical  fibres  of  the  outer  surface :  many  seem  to  arise 
independently  within  the  ventricular  wall.  According  to  Henle, 
all  the  external  longitudinal  fibres  do  not  arise  from  the  fibrous  rings 
or  the  roots  of  the  arteries. 

[The  assumption  that  the  muscles  of  the  ventricle '  are  arranged  so  as  to  form 
a  figure  of  8,  or  in  loops,  seems  to  be  incorrect ;  thus,  fibres  are  said  to  arise  at  the 
base  of  the  ventricle,  to  pass  over  it,  and  to  reach  the  vortex,  where  they  pass 
into  the  interior  of  the  muscular  substance,  to  end  either  in  the  papillary  muscles, 
or  high  up  on  the  inner  surface  of  the  heart  at  its  base.  Figs.  C  and  D  give  a 
schematic  representation  of  this  view.] 

A  special  layer  of  circular  r)%umula,r  fibres,  which  acts  like  a  true 
sphincter,  surrounds  the  arterial  opening  of  the  left  ventricle,  and 
seems  to  have  a  certain  independence  of  action  (Henle). 


PERICARDIUM,  ENDOCARDIUM,   VALVES, 


71 


Only  the  general  arrangement  of  the  ventricular  muscular  fibres  has  been 
indicated  here  (Lower,  Casp.  Wolff,  1780-92).  C,  Ludwig  (1849),  and  more 
recently  Pettigrew  (1864)  have  made  the  subject  a  special  study,  and  followed  out 
its  complications.  According  to  the  last  obserA'er,  there  are  seven  layers  in  the 
ventricle,  viz.,  three  external,  a  fourth  or  central  layer,  and  three  internal.  These 
internal  layers  are  continuous  with  the  corresponding  external  layers  at  the  apex, 
thus — one  and  seven,  two  and  six. 

46.  Pericardium,  Endocardium,  Valves. 

The  PERICARDIUM  encloses  within  its  two  layers  [visceral  and  parietal]  a  lymph 
space — the  pericardial  space — which  contains  a  small  quantity  of  lymph — the 
pericardial  fluid.  It  has  the  structure  of  a  serous  membrane,  i.e.,  it  consists  of 
connective  iiesue  mixed  with/"ne  elastic  fibres  arranged  in  the  form  of  a  thin  delicate 
membrane,  and  covered  on  its  free  surfaces  with  a  single  layer  of  epithelium  or 
endothelium,  composed  of  irregular,  polygonal,  flat  cells. 

A  rich  lymphatic  netivork  lies  under  the  pericardium  (fig.  20)  and  endocardium 
and  also  in  the  deeper  laj'ers  of  the  visceral  pericardium  next  the  heart,  but  stomata 
have  not  been  found  leading  from 
the  pericardial  cavity  into  these 
lymphatics,  nor  do  these  open- 
ings exist  on  the  j^nrietal  layer. 
[Sah-ioli  has  shown  that  lym- 
phatic spaces  also  lie  between 
the  muscular  bundles.]  Around 
the  coronary  arteries  of  the  heart 
exist  deposits  of  fat  and  lymph- 
vessels  (Wedl),  which  lie  in  the 
furrows  and  grooves  in  the  sub- 
serosa  of  the  epicardium  (visceral 
layer). 

The  ENDOCARDIUM  (according  to 
Luschka)  does  not  represent  the 
intima  alone,  but  the  entire  wall 
of  a  blood-vessel.  Next  the  ca^^ty 
of    the    heart,  it   consists   of   a 
single  layer    of   polygonal,   flat, 
nucleated  endothelial  cells.     [Under  this  there  is  a  nearly  homogeneous  hyaline 
layer  (fig.  21,  a),  slightly  thicker  on  the  left  side,  which  gives  the  endocardium  its 
polished  appearance.]      Then 
follows,   as    the   basis   of  the 
membrane,  a  layer  of /we  elastic 
fibres— stronger  in  the  auricles, 
and  in  some  places  thereof  as- 
suming  the    characters   of   a 
fenestrated   membrane.       Be- 
tween   these    fibres    a    small 
quantity  of  connective  tissue 
exists,    which     is     in     larger 
amount  and  more  areolar  in  its 
characters  next  the  myocar- 
dium.    Bundles  of  non-striped 
muscular  fibres   (few   in    the 
auricles)     are    scattered    and 
arranged  for    the   most   part 
longitudinally    between     the 


Fig.  20. 

Lymphatic  of  the  pericardium  epithelium  stained 

with  nitrate  of  silver. 


Fig.  21. 
Section  of  the  endocardium — a,  hyaline  layer  :  h, 
network  of  fine  elastic  fibres ;  c,  network  of 
stronger  elastic  fibres ;  d,  myocardium  with 
blood-vessels,  which  do  not  pass  into  the  endo- 
cardium. 


72  STRUCTURE  OF  THE  VALVES. 

elastic  fibres.  These  seem  evidently  meant  to  resist  the  distension  which  is 
apt  to  occur  when  the  heart  contracts  and  great  pressure  is  put  upon  the 
endocardium.  In  all  cases  where  high  pressure  is  put  upon  walls  composed  of 
soft  parts,  we  always  find  muscular  fibres  present,  and  never  elastic  fibres  alone. 
No  blood-vessels  occur  in  the  endocardium  (Langer). 

The  valves  also  belong  to  the  endocardium — both  the  semi-lunar  valves 
of  the  aorta  and  pulmonary  artery,  which  prevent  the  blood  from  passing 
back  into  the  ventricles,  and  the  tricuspid  (right  auriculo-ventricular) 
and  mitral  (left  auriculo-ventricular),  which  protect  the  auricles  from 
the  same  result.  The  lower  vertebrata  have  valves  in  the  orifices  of 
the  venae  cavse  which  prevent  regurgitation  into  them;  while  in  birds 
and  some  mammals  these  valves  exist  in  a  rudimentary  condition. 

The  VALVES  are  fixed  by  means  of  their  base  to  resistant  fibrous 
rings,  consisting  of  elastic  and  fibrous  tissue.  They  are  formed  of 
two  layers — (1.)  i\iQ  fibrous,  which  is  a  direct  continuation  of  the  fibrous 
rings,  and  (2.)  a  layer  of  elastic  elements.  The  elastic  layer  of  the 
auriculo-ventricular  valves  is  an  immediate  prolongation  of  the 
endocardium  of  the  auricles,  and  is  directed  towards  the  auricles. 
The  semi -lunar  valves  have  a  thin  elastic  layer  directed  towards  the 
arteries,  which  is  thickest  at  their  base.  The  connective-tissue  layer 
directed  towards  the  ventricle  is  about  half  the  thickness  of  the 
valve  itself. 

Muscular  Fibres  in  the  Valves. — The  auriculo-ventricular  valves 
also  contain  stri])ecl  muscular  fibres  (Eeid,  Gussenbauer).  Eadiating 
fibres  proceed  from  the  auricles  and  pass  into  the  valves,  which,  when 
the  atria  contract,  retract  the  valves  towards  their  base,  and  thus  make 
a  larger  opening  for  the  passage  of  the  blood  into  the  ventricles;  accord- 
ing to  Paladino,  they  raise  the  valves  after  they  have  been  pressed 
down  by  the  blood-current.  This  observer  also  described  some  longi- 
tudinal fibres  which  proceed  from  the  ventricles  to  enter  these  valves. 
There  is  also  a  concentric  layer  of  fibres  arranged  near  their  point  of 
attachment,  and  directed  more  towards  their  ventricular  surface. 
These  fibres  seem  to  contract  sphincter-like  when  the  ventricle  contracts, 
and  thus  approximate  the  base  of  the  valves,  and  so  prevent  too  great 
tension  being  put  upon  them.  The  larger  chordae  tendinise  also 
contain  striped  muscle  (Oehl),  while  a  delicate  muscular  network 
exists  in  the  valvula  thebesii  and  valvula  eustachii. 

PurMnje's  Fibres. — This  name  is  applied  to  an  anastomosing  system  of 
grayish  fibres  which  exist  in  the  sub-endocardial  tissue  of  the  ventricles,  especially 
in  the  heart  of  the  sheep  and  ox.  The  fibres  are  made  up  of  polyhedral,  clear  cells, 
containing  some  granular  protoplasm,  and  usually  two  nuclei  (Fig.  22).  The 
margins  of  the  cells  are  striated.  Transition  forms  are  found  between  these  cells 
and  the  ordinary  cardiac  fibres ;  in  fact  these  cells  become  continuous  -with  the 
true  fully  developed  cardiac  fibres.    They  represent  cells  which  have  been  arrested 


SELF-STEERING   ACTION    OF  THE   HEART. 


73 


Fig.  22. 

ruikinje's  fibres  isolated  with  dilute  alcohol — c,  cell ; 
/,  striated  substance  ;  n,  nucleus —  x  300. 


in  their  development.  They  are  absent  in  man  and  the  lower  vertebrates,  but  in 
birds  and  some  mammals  they  are  well  marked  (Schweigger-Seidel,  Rauvier), 

Blood -Vessels    occur 

in  the  auriculo-ventricular 
valves  only  where  mus- 
cular fibres  are  present, 
while  the  semi  -  lunar 
valves  are  iisually  devoid 
of  vessels  except  at  their 
base.  The  best  figures 
of  the  blood-vessels  of 
the  valves  are  given  by 
Langer.  The  network  of 
hjmplmtics  in  the  en- 
docardium reaches  to- 
wards the  middle  of 
the  valves  (Eberth  and 
Belajeff). 

Weight  of  the  Heart. 

— According  to  W.  ^luller 
the  proportion  between 
the  weight  of  the  body  and  the  heart  in  the  child,  and  until  the  body  reaches 
40  kilos.,  is  5  grams,  of  heart-substance  to  1  kilo,  of  body -weight ;  when  the 
body-weight  is  from  50  to  90  kilos.,  the  ratio  is  1  kilo,  to  4  grams,  of  heart- 
substance  ;  at  100  kilos.  3 '5  grams.  As  age  advances,  the  auricles  become 
stronger.  The  right  ventricle  is  half  the  weight  of  the  left.  The  weight  of  tlie 
heart  of  an  adult  man  is  about  9  oz.  (1  oz.  =29*2  gi-ms.);  female  =  84  oz.  (Clen- 
dinning  as  a  mean  of  400  observations).  [According  to  Laennec  the  heart  is  about 
the  size  of  the  closed  fist  of  the  individual].  Blosfield  and  Dieberg  give  346  grms. 
for  the  male,  and  310  to  340  grms.  for  the  female  heart.  The  specific  gravity  of 
the  heart-muscle  is  1'069  (Kapff). 

47.  Self-Steering  Action  of  the  Heart. 

Coronary  Vessels. — Many  observations  have  been  made  to  ascertain 
whether  the  orifices  of  the  coronary  arteries  are  covered  by  the  semi- 
hmar  valves  during  contraction  of  the  left  ventricle  (Thebesius,  1739; 
Briicke,  1854),  or  whether  they  are  permanently  open  (Morgagni,  1723; 
Hyrtl,  1855)— Fig.  23. 

Anatomical    Investigations The    two    coronary    arteries   whose 

branches  do  not  anastomose  (Hyrtl,  Henle;  but  this  is  denied  by 
Krause  and  L.  Langer),  arise  from  the  beginning  of  the  aorta  in  the 
region  of  the  sinus  of  Valsalva,  The  position  of  origin  varies — (1.) 
either  the  origins  lie  within  the  sinus,  or  (2,)  their  openings  are  only 
partially  reached  by  the  margins  of  the  semi-lunar  valves  (which  is 
umally  the  case  in  the  left  coronary  artery  of  man  and  the  ox),  or  (3.) 
their  orifices  lie  clear  above  the  margins  of  the  valves.  Post-mortem 
observations  seem  to  show  that  during  contraction  of  the  ventricle,  it 
is  very  improbable  that  the  semi-lunar  valves  constantly  cover  the 
origin  of  the  coronary  arteries. 


74  SELF-STEERING   ACTION   OF  THE  HEART. 

The  Self-Steering  Action  of  the  Heart. — Briicke  attempted  to  show 
that  during  the  systole,  or  contraction  of  the  ventricle,  the  semi-lnnar 
valves  covered  the  openings  of  the  coronary  arteries,  so  that  these 
vessels  could  be  filled  with  blood  only  during  the  diastole  or  relaxation 
of  the  ventricle.  To  him  it  seemed  that  (a.)  the  diastolic  filling  of  the 
coronary  arteries  would  help  to  dilate  the  ventricles ;  (&.)  on  the  con- 
trarj^,  a  systolic  filling  of  these  arteries  would  oppose  the  contraction, 
because  the  systolic  filling  and  expulsion  of  the  blood  from  the 
coronary  arteries  would  diminish  the  force  of  the  ventricular  contrac- 
tion.    To  this  arrangement,  Briicke  gave  the  above  name. 

Arguments  against  Briicke's  View. — The  following  considerations  militate 
against  this  theory  :—(l.)  FUIing  the  coronary  vessels  under  a  high  pressure  in  a 
dead  heart  eauses  a,  diminution  of  the  ventricular  cavity  (v.  Wittich).  (2.)  The 
chief  trunks  of  the  coronary  arteries  lie  in  loose  sub-pericardial  fatty  tissue,  in  the 
cardiac  sulci,  hence  a  dilatation  of  the  ventricle  through  this  agency  is  most 
unlikely  (Landois).  (.3.)  Experiments  on  animals  have  shown  that  a  coronary 
artery  spouts,  like  all  arteries,  during  the  systole  of  the  ventricle.  Von  Ziemssen 
found  that  in  the  case  of  a  woman  (Serafiu),  who  had  a  large  part  of  the  anterior 
wall  of  the  thorax  removed  by  an  operation,  the  heart  being  covered  only  by  a 
thin  membrane,  the  pulse  in  the  coronary  arteries  was  synchronous  with  the 
pulse  in  the  pulmonary  artery.  H.  N.  Martin  and  Sedgwick  placed  a  manometer 
in  connection  with  the  coronary  artery,  and  another  with  the  carotid  in  a  large- 
dog,  and  they  found  that  the  pulsations  occurred  simultaneously.  When  a  coronary 
artery  is  divided,  the  blood  flows  out  continuously,  but  undergoes  acceleration  during 
the  systole  of  the  ventricles  (Endemann,  Perls).  (4.)  If  a  strong  intermitteuj 
current  of  water  be  allowed  to  flow  through  a  sufficiently  wide  tube  into  the  left 
auricle  of  a  fresh  pig's  heart,  so  that  the  water  passes  into  the  aorta,  and  if  the  aorta 
be  provided  with  a  vertical  tube,  the  water  flows  continuously  from  the  coronary^ 
arteries,  and  is  accelerated  during  the  systole.  (5.)  It  is  exceedingly  improbable 
that  the  coronary  arteries  should  be  filled  during  the  diastole  while  all  the  other 
arteries  are  filled  during  systole  of  the  ventricle.  (6. )  There  is  always  a  sufl&cient 
quantity  of  blood  in  the  sinus  of  Valsalva  to  fill  the  arteries  during  the  first  part  of 
the  systole.  (7.)  The  valves,  when  raised,  are  not  applied  directly  to  the  aortic 
wall  (Hamberger,  Eiidinger)  even  by  the  most  energetic  pressure  from  the  ventricle 
(Sandborg  and  Worm  Mtiller).  (8.)  Observations  on  volimtary  muscles  have  shovn 
that  the  small  arteries  dilate  during  contraction  of  the  muscle,  and  the  blood 
stream  is  accelerated.  (9. )  By  the  systolic  filling  of  the  aorta  the  arterial  path  is 
elongated — this  elastic  distension  is  compensated  before  the  diastole  occurs.  By 
the  recoil  of  the  aortic  walls  the  layer  of  blood  in  them  is  drH^en  backwards  aid 
closes  the  valves  (Ceradini).  According  to  Sandborg  and  Worm  Mtiller,  the  seiii- 
lunar  valves  close  just  after  the  ventricles  have  begun  to  relax,  which  agrees  with 
the  curve  obtained  from  the  cardiac  impulse  (Fig.  25a,  A). 

During  the  systole,  the  small  arterial  trunks  lying  next  the  ventri'iu- 
lar  cavities  have  to  bear  a  higher  pressure  than  that  borne  by  the 
aorta,  and  their  lumen  must  be  compressed  during  the  systole  so  tlat 
their  contents  are  propelled  towards  the  veins. 

Peculiarities  of  the  Cardiac  Blood-Vessels.— The  capillary  vessels  of  -.he 

myocardium  are  very  numerous,  corresponding  to  the  energetic  activity  of  :he 


LIGATURE   OF  THE   CORONARY   ARTERIES.  75 

heart.  Where  they  pass  into  veins,  several  unite  at  once  to  form  a  thick  venous 
trunk  whereby  an  easy  passage  is  offered  to  the  blood.  The  vins  arc  provided 
with  valves  so  that  (1.)  during  systole  of  the  right  auricle  the  venous  stream  is 
interrupted;  (2.)  during  contraction  of  the  ventricles  the  blood  in  the  coronary 
veins  is  similarly  accelerated  as  in  the  veins  of  muscles. 

The  coronary  arteries  are  characterised  by  their  very  thick  connective  tissue  and 
elastic  intima,  which  perhaps  accounts  for  the  frequent  occurrence  of  atheroma  of 
these  vessels  (Henle).  Some  observers  (Hyrtl  and  Henle)  maintain  that  the 
coronary  arteries  do  not  anastomose,  but  this  is  denied  by  Langer  and  Krause. 
Many  of  the  small  lower  vertebrates  have  no  blood-vessels  in  their  heart-muscle, 
e.g.,  frog  (Hyrtl). 

Coronary  Circulation. — The  phenomena  produced  by  partial  oblitera- 
tion or  ligature  of  the  coronary  arteries  are  most  important.  In  man 
analogous  conditions  occur,  as  in  atheroma  or  calcification  of  these 
arteries. 

Ligature  of  the  Coronary  Arteries. — See  and  others  ligatured  the 
coronary  arteries  in  a  dog,  and  found  that  after  2  minutes  the  cardiac 
contractions  gave  place  to  tmtchings  of  the  muscular  fibres,  and 
ultimately  the  heart  ceased  to  beat.  Ligature  of  the  anterior 
coronary  artery  alone,  or  of  both  its  branches,  is  sufficient  to  produce 
this  result. 

If  the  coronary  arteries  be  compressed  or  tied  in  a  rabbit  in  the 
angle  between  the  bulbus  aortfe  and  the  ventricle,  the  heart's  action  is 
soon  weakened,  owing  to  the  sudden  anjemia  and  to  the  retention  of 
the  decomposition  products  of  the  metabolism  in  the  heart-muscle  (v. 
Bezold,  Erichsen).  Ligature  of  one  artery  first  affects  the  corresponding 
ventricle,  then  the  other  ventricle,  and,  last  of  all,  the  auricles.  Hence, 
compression  of  the  left  coronary  artery  (with  simultaneous  artificial 
respiration  in  a  curarised  animal)  causes  slo^^^ng  of  the  contractions, 
especially  of  the  left  ventricle,  whilst  the  right  one  at  first  contracts 
more  quickly  and  then,  gradually,  its  rhythm  is  slowed.  The  contrac- 
tions of  the  left  ventricle  are  not  only  slowed  but  also  weakened, 
whilst  the  right  pulsates  with  undiminished  force.  Hence  it  follows 
that  as  the  left  half  of  the  heart  cannot  expel  the  blood  in  suffi- 
cient quantity,  the  left  auricle  becomes  filled,  Avhilst  the  right 
ventricle,  not  being  aff"ected,  pumps  blood  into  the  lungs.  (Edema  of 
the  lungs  is  produced  by  the  high  pressure  in  the  pulmonary  circula- 
tion, which  is  propagated  from  the  right  heart  through  the  pulmonary 
vessels  into  the  left  aiiricle  (Samuelson  and  Griinhagen). 

According  to  Sig.  Mayer,  protracted  dyspnoea  causes  the  left  ventricle 
to  beat  more  feebly  sooner  than  the  right,  so  that  the  left  side  of  the 
heart  becomes  congested.  Perhaps  this  may  explain  the  occurrence 
of  pulmonary  oedema  during  the  death  agony. 

Cohnheim  and  v.  Schulthess-Rechberg  found  after  ligature  of  one  of  the  large 
branches  of  a  coronary  artery  in  a  large  dog,  that  at  the  end  of  a  minute  the 


76   ■  THE  MOVEMENTS  OF  THE  HEART. 

pulsations  become  discontinuous;  several,  as  it  were,  do  not  occur.  This  inter- 
mittence  becomes  more  pronounced,  the  two  sides  of  the  heart  do  not  contract 
simultaneously  (arhi/thmia),  the  heart  beats  more  slowly,  and  the  blood-pressure 
falls.  Suddenly,  about  105  sees,  after  the  ligature  is  applied,  both  ventricles  cease 
to  beat,  and  there  is  the  greatest  fall  of  the  blood-pressure.  After  10  to  20  sees., 
tmtching  movements  occur  in  the  ventricles,  while  the  auricles  pulsate  regularly, 
and  may  continue  to  do  so  for  many  minutes,  while  the  ventricles  cease  to  beat 
altogether  after  50  sees.  According  to  LukjanoM",  there  is  a  peristaltic  condi- 
tion which  operates  upwards  and  do-miwards,  and  occurs  in  the  period  between 
the  regular  contraction  and  the  twitching  vibratory  movement. 


48.  The  Movements  of  the  Heart. 

Cardiac  Revolution. — The  movement  of  the  heart  is  characterised  by 
an  alternate  contraction  and  relaxation  of  the  cardiac  walls.  The 
total  cardiac  movement  is  called  a  "  CARDIAC  revolution,"  or  a 
"  cardiac  cycle,"  and  consists  of  three  acts — the  contraction  or  stjstole 
of  the  auricles,  the  contraction  or  systole  of  the  ventricles,  and  the  ]yaiisc. 
During  the  pause  the  auricles  and  ventricles  are  relaxed ;  during  the 
contraction  of  the  auricles  the  ventricles  are  at  rest;  whilst  during 
the  contraction  of  the  ventricles,  the  auricles  are  relaxed.  The  rest 
during  the  phase  of  relaxation  is  called  the  cUastok.  The  following 
is  the  sequence  of  events  in  the  heart  during  a  cardiac  revolution  : — 

Events  During  a  Cardiac  Eevolution. 

(A.)  The  Blood  Flows  into  the  Auricles,  and  thus  distends  them  and 
the  auricular  appendages.     This  is  caused  by — 

(1.)  The  pressure  of  the  blood  in  the  venae  cavse  (right  side)  and  the 
pulmonary  veins  (left  side)  being  greater  than  the  pressure  in  the 
auricles. 

(2.)  The  elastic  traction  of  the  lungs  (§  60)  which,  after  complete 
systole  of  the  auricles,  pulls  asunder  the  now  relaxed  and  yielding 
auricular  walls.  The  auricular  appendages  are  also  filled  at  the 
same  time,  and  they  act  to  a  certain  extent  as  accessory  reservoirs 
for  the  large  supply  of  blood  streaming  into  the  auricles. 

(B.)  The  Auricles  Contract,  and  we  observe  in  rapid  succession — 

(1.)  The  contraction  and  emptying  of  the  auricular  appendix 
towards  the  atrium.  Simultaneously  the  mouths  of  the  veins  become 
narrowed  (Haller,  Xysten)  owing  to  the  contraction  of  their  circular 
muscular  fibres  (more  especially  the  superior  vena  cava  and  the 
pulmonary  veins). 

(2.)  The  auricular  walls  contract  simultaneously  towards  the  auiiculo- 
ventricular  valves  and  the  venous  orifices,  whereby 


EVENTS   DURING   A   CARDIAC    CYCLE. 


77 


(3.)  The  blood  is  driven  into  the  relaxed  ventricles,  which  are  con- 
siderably distended  thereby. 

The  contraction  of  the  auricles  is  followed  by 

(a.)  A  slight  stagnation  of  the  blood  in  the  large  venous  trunks,  as 
can  be  easily  observed  in  a  rabbit  after  division  of  the  pectoral  muscles 
so  as  to  expose  the  junction  of  the  jugular  with  the  subclavian  vein. 
There  is  no  proper  regurgitation  of  the  blood,  but  only  a  partial 
interruption  of  the  inflow  into  the  auricles,  because,  as  already  men- 
tioned, the  mouths  of  the  veins  are  contracted,  and  because  the 
pressure  in  the  superior  vena  cava  and  in  the  pulmonary  veins  soon 
holds  in  equilibrium  any  reflux  of  blood;  and  lastly,  because  any  reflux 


Gypsum  cast  of  the  Aentricles  of  the  human  heart — viewed  from  behind  and  above; 
the  walls  have  been  removed,  and  only  the  fibrous  rings  and  the  auriculo- 
ventricular  valves  are  retained— L,  left,  R,  right  ventricle ;  S,  position  of 
septum  ;  F,  left  fibrous  ring,  with  mitral  valve  closed;  D,  right  fibrous  ring, 
\vith  tricuspid  closed  ;  A,  aorta,  with  the  left  (Ci)  and  right  (C)  coronary 
arteries  ;  S,  sinus  of  valsalva  ;  P,  pulmonary  artery. 


78  EVENTS    DURING   A    CARDIAC    CYCLE. 

into  the  cardiac  veins  is  prevented  by  valves.  The  movement  of  the 
heart  causes  a  regular  pulsatile  phenomenon  in  the  blood  of  the  venae 
cavae,  which  under  abormal  circumstances  may  produce  a  venous  pulse 
(see  Venous  pulse). 

(b.)  The  chief  motor  effect  of  the  contraction  of  the  auricles  is  the 
dilatation  of  the  relaxed  ventricle,  which  has  already  been  dilated  to  a 
slight  extent  by  the  elastic  force  of  the  lungs. 

The  dilatation  of  the  ventricles  has  been  ascribed  to  the  elasticity  of  the 
muscular  walls — the  strongly  contracted  ventricular  walls  (like  a  compressed  india- 
rubber  bag),  in  virtue  of  their  elasticity,  are  supposed  to  return  to  their  normal 
resting  form,  and  thereby  to  suck  in  or  aspirate  the  blood  under  a  negative  pres- 
sure. Such  suction  power  on  the  part  of  the  ventricle  is,  however,  only  effective 
to  a  very  slight  extent. 

(c.)  When  the  ventricles  are  distended  by  the  inflowing  blood,  the 
auriculo-ventricular  valves  are  floated  up,  partly  by  the  recoil  or 
reflexion  of  the  blood  from  the  ventricular  wall,  and  partly  owing  to 
their  lighter  specific  gravity,  whereby  they  easily  float  into  a  more  or 
less  horizontal  position.  The  valves  are  also  raised  to  a  slight  extent 
by  the  longitudinal  muscular  fibres,  which  pass  from  the  auricles  into 
the  cusps  of  the  valve  (Paladino). 

(C.)  The  Ventricles  now  Contract,  and  simultaneously  the  auricles 
relax,  whereby 

(1.)  The  muscular  walls  contract  forcibly  from  all  sides,  and  thus 
diminish  the  ventricular  cavity, 

(2.)  The  blood  is  at  once  pressed  against  the  under-surface  of  the 
auriculo-ventricular  valves,  whose  curved  margins  are  opposed  to  each 
other  Uke  teeth,  and  are  pressed  hermetically  against  each  other  (Sand- 
borg  and  Worm  Miiller).  It  is  impossible  for  the  blood  to  push  the 
cusps  backwards  into  the  auricle,  as  the  chordce  tendinioi  hold  fast  their 
margins  and  surfaces  Hke  a  taut  sail.     The  margins  of  the  neighbouring 

cusps  are    also  kept   in  apposition  by  the 

chordce  tendinise  from  one  papillary  muscle 

always  passing   to  the  adjoining   edges  of 

two  cusps    (John   Eeid).      The    extent   to 

which  the  ventricular  wall  is  shortened  is 

compensated    by    the    contraction    of   the 

papillary   muscle,    and    also    of  the   large 

muscular  chordae,  so  that  the  cusps  cannot 

Ijc  pushed  into  the  auricle. 

"p~24^  When  the  valves  are  closed  then-  surfaces 

The    closed    semi-lunar    a,re    horizontal,    so    that    even   when   the 

valves   of   the  pulmonary    ventricles  are  contracted  to  their  greatest 

artery  seen  from  below.         extent,  a  small  amount  of  blood  remains, 

which  is  not  expelled  (Sandborg  and  Worm  Miiller). 


PATHOLOGICAL   DISTURBANCES   OF    CARDIAC  ACTION.  79 

(3.)  Opening  of  the  Semi-lunar  Valves. — When  the  pressure  within 
the  ventricle  exceeds  that  in  the  arteries,  the  semi-lunar  valves  are 
forced  open  and  stretched  like  a  sail  across  the  pocket-like  sinus, 
without,  however,  being  firmly  or  directly  applied  to  the  wall  of  the 
arteries  (pulmonary  and  aorta),  and  thus  the  blood  enters  the  arteries. 

Negative  Pressure  in  the  Ventricle.— Goltz  and  Gaule  found  that  there  was 

a  negative  pressure  of  23*5  mm.  Hg.  (dog)  in  the  interior  of  the  ventricle  during  a 
certain  phase  of  the  heart's  action.  They  surmised  that  that  phase  coincided  witli 
the  diastolic  dilatation,  for  which  they  assumed  a  considerable  power  of  aspiration. 
Marey  observed  a  similar  condition  and  called  it  "  vacuite  postsystolique,"  but 
thought  that  it  coincided  with  the  end  of  the  systole;  while  Moens  is  of  opinion  that 
this  negative  pressure  within  the  ventricle  obtains  shortly  before  the  systole  has 
reached  its  height,  i.e.,  just  before  the  inner  surface  of  the  ventricles  and  the 
valves,  after  the  blood  is  expelled,  are  nearly  in  apposition.  He  explains  this 
aspiration  as  being  due  to  the  formation  of  an  empty  space  in  the  ventricle  caused 
by  the  energetic  expulsion  of  the  blood  through  the  aorta  and  pulmonary  artery. 

(D.)  Pause. — As  soon  as  the  ventricular  contraction  ends,  and  the 
ventricles  begin  to  relax,  the  semi-lunar  valves  close.  The  diastole  of 
the  ventricles  is  followed  by  the  pause.  Under  normal  circumstances 
the  right  and  left  halves  of  the  heart  always  contract  or  relax  uni- 
formly and  simultaneously. 

49.  Pathological  Disturbances  of  Cardiac  Action. 

Cardiac  Hypertrophy. — All  eesistaxces  to  the  movement  of  the  blood 
through  the  various  compartments  of  the  heart,  and  through  the  vessels  com- 
municating witli  it,  cause  a  greater  amount  of  work  to  be  thrown  upon  the 
portion  of  the  heart  specially  related  to  this  part  of  the  circulatory  system ;  con- 
sequently, there  is  produced  an  increase  in  the  thickness  of  the  muscular  walls 
and  dilatation  of  the  heart.  If  the  resistance  or  obstacle  does  not  act  upon 
one  part  of  the  heart  alone,  but  on  parts  lying  in  the  onioard  direction  of  the 
blood-stream,  these  parts  also  subsequently  undergo  hypertrophy.  If  in  addi- 
tion to  the  muscular  thickening  of  a  part  of  the  heart  the  cavity  is  simultaneously 
dilated,  it  is  spoken  of  as  eccentric  hypertrophy  or  hypertrophy  with  dilatation. 

The  obstacles  most  likely  to  occur  in  the  blood-vessels  are  narrowing  of  the 
lumen  or  want  of  elasticity  in  their  walls  ;  in  the  heart,  narrowing  of  the  arterial 
or  venous  orifices  or  insufficiency  or  incompetency  of  the  valves.  Incompetency 
of  the  valves  forms  an  obstruction  to  the  movement  of  the  blood,  by  allowing 
part  of  the  blood  to  flow  back  or  regurgitate,  thus  throwing  extra  work  upon 
the  heart. 

Thus  arise — (1.)  Hypertrophy  of  the  left  ventricle,  owing  to  resistance  in  the  area 
of  the  systemic  cii'culation,  especially  in  the  arteries  and  capillaries — not  in  the 
veins.  Amongst  the  causes  are,  constriction  of  the  orifice  or  other  parts  of  the 
aorta,  calcification,  atheroma,  and  want  of  elasticity  of  the  large  arteries  and 
irregular  dilatations  in  their  course  (Aneurisms) ;  insufficiency  of  the  aortic 
valves,  in  which  case  the  same  pressure  always  obtain  within  the  ventricle  and  in 
the  aorta ;  and  lastly,  contraction  of  the  kidneys,  so  that  the  excretion  of  water  by 
these  organs  is  diminished.  Even  in  mitral  insufficiency  compensatory  hyper- 
trophy of  the  left  ventricle  must  occur,  owing  to  the  hypertrophy  of  the  left  atrium 
iu  consequence  of  the  increased  blood-pressure  in  the  pulmonary  circuit. 


80  THE   APEX-BEAT, 

(2. )  Hj'pertrophy  of  the  left  auricle  occurs  in  stenosis  of  tlie  left  auriculo-ven- 
tricular  orifice,  or  in  insufficiency  of  the  mitral  valve,  and  it  occurs  also  as  a  result 
of  aortic  insufficiency,  because  the  auricle  has  to  overcome  the  continual  aortic 
pressure  within  the  ventricle, 

(3.)  Hypertrophy  of  the  right  ventricle,  occurs  (a.)  when  there  is  resistance  to 
the  blood-stream  through  the  pulmonary  circuit.  The  resistance  may  be  due  to 
(a.)  obliteration  of  large  vascular  areas  in  consequence  of  destruction,  shrinking  or 
compression  of  the  lungs,  and  the  disappearance  of  numerous  capillaries  in  emphy- 
sematous lungs.  (/3.)  Overfilling  of  the  pulmonary  circuit  with  blood  in  conse- 
quence of  stenosis  of  the  left  auriculo-ventricular  orifice  or  mitral  insufficiency — 
consequent  upon  hypertrophy  of  the  left  auricle  resulting  from  aortic  insufficiency, 
(b. )  Hypertrophy  of  the  right  ventricle  wUl  also  occur  when  the  valves  of  the 
pulmonary  artery  are  insufficient,  thus  permitting  the  blood  to  flow  back  into  the 
ventricle,  so  that  the  pressure  within  the  pulmonary  artery  prevails  within  the 
right  ventricle  (very  rare). 

(4.)  Hypertrophy  of  the  right  auricle  occurs  in  consequence  of  the  last-named 
condition,  and  also  from  stenosis  of  the  tricuspid  orifice,  or  insufficiency  of  the 
tricuspid  valve  (rare).  If  several  lesions  occur  simultaneously,  the  result  is 
complex. 

Artificial  Injury  to  the  Valves. — 0.  Rosenbach  has  made  experiments  on 
the  action  of  the  heart  when  its  valves  are  injured  artificially.  If  the  aortic  valves 
are  perforated,  with  or  without  simultaneous  injury  to  the  mitral  or  tricuspid 
valves,  the  heart  does  more  work ;  thus  the  physical  defect  is  overcome  for  a  time, 
so  that  the  blood-pressure  does  not  fall.  The  heart  seems  to  have  a  store  of 
reserve  energy,  which  is  called  into  play.  Soon,  however,  dilatation  takes  place, 
on  account  of  the  regurgitation  of  the  blood  into  the  heart.  Hypertrophy  then 
occurs,  but  the  compensation  meanwhile  must  be  obtained  through  the  reserve 
en'ergy  of  the  heart. 

Impeded  Diastole. — Among  causes  which  hinder  the  diastole  of  the  heart  are — 
copious  effusions  into  the  peiicardium,  or  pressure  of  tumours  upon  the  heart.  The 
systole  is  greatly  interfered  with  Avhen  the  heart  is  united  to  the  pericardium  and 
to  the  connective  tissue  in  the  mediastinum.  As  a  consequence  the  connective 
tissue,  and  even  the  thoracic  wall,  are  drawn  in  during  conti'action  of  the  heart, 
so  that  there  is  a  retraction  of  the  region  of  the  apex-beat  during  systole,  and  a 
protrusion  of  this  part  during  the  diastole. 


50.  The  Apex-Beat— The  Cardiogram. 

Cardiac  Impulse. — By  the  term  "apex-beat,"  or  cardiac  impulse,  is 
understood  under  normal  circumstances  an  elevation  (perceptible  to 
touch  and  sight)  in  a  circumscribed  area  of  the  ffth  left  intercostal 
space,  caused  by  the  movement  of  the  heart,  [The  apex-beat  is  felt  in 
the  fifth  left  intercostal  space,  two  inches  below  the  nipple,  and  one 
inch  to  its  sternal  side.]  The  impulse  is  more  rarely  felt  in  the  fourth 
intercostal  space,  and  it  is  much  less  distinct  when  the  heart  beats 
against  the  fifth  rib  itself.  The  position  and  force  of  the  cardiac 
impulse  vary  ^Yith.  changes  in  the  position  of  the  body. 

[Methods. — To  obtain  a  curve  of  the  apex-beat  or  a  cardiogram,  we  may 
use  one  or  other  of  the  folloMong  cardiographs  (Fig.  25).  Fig,  25,  A,  is  the 
first  form  used  by  Marey,  and  it  consists  of  an  oval  wooden  capsule  applied  in  an 


THE   CARDIOGRAM. 


«1 


air-tight  manner  over  the  apex-beat.  The  disc,  "p,  capable  of  being  regulated  by  the 
screw,  s,  presses  upon  the  region  of  the  apex-beat,  while  t  is  a  tube  which  may 
be  connected  with  a  registering  tambour  (Fig.  28).  B  is  an  improved  form  of 
the  instrument,  consisting  essentially  of  a  tambour,  while  attached  to  the  mem- 
brane is  a  button,  i^,  to  be  applied  over  the  apex-beat.  The  movements  of  the  air 
within  the  capsule  are  communicated  by  the  tube,  t,  to  a  registering  tambour.  Fig. 
25,  C,  is  the  pansphygmograph  of  Brondgeest,  which  consists  of  a  Marey's  tam- 
boui',  in  an  iron  horse-shoe  frame,  and  adjustable  by  means  of  asci'ew,  s.  Burdon- 
Sanderson's  cardiograph  is  shown  in  D.  The  button,  f,  carried  by  the  spring,  e, 
does  not  rest  upon  the  caoutchouc  membrane,  but  on  an  aluminium  plate 
attached  to  it.  The  apparatus  is  adjusted  to  the  chest  by  three  supports. 
Fig.  25,  E,  shows  a  modified  instrument  on  the  same  principle  by  Grunmach 
and  V.  Knoll.  In  all  these  figures  the  t  indicates  the  exit-tube  communicating 
with  a  registering  tambour  (Fig.  28).  D  and  E  may  be  used  for  other  purposes, 
e.g.,  for  the  pulse,  so  that  they  iiVQ  polyrjraphs.     See  also  Fig.  52.] 


Fig.  25. 

Various  cardiographs — A,  original  form  as  used  by  Marey ;  B,  improved  form  by 
Marey;  C,  Pansphygmograph  of  Brondgeest;  D,  Cardiograph  of  Burdon- 
Sanderson  ;  E,  that  of  Grunmach  and  v.  Knoll. 


Fig.  25  a,  A,  shows  the  cardiogram  or  the  impulse -curve  of  the  heart  of 
a  healthy  man ;  B,  that  of  a  dog,  obtained  by  means  of  a  sj)liygmo- 
graph.  In  both  the  following  points  are  to  be  noticed — a,  h,  corre- 
sponds to  the  time  of  the  pause  and  the  contraction  of  the  auricles.  As 
the  atria  contract  in  the  direction  of  the  axis  of  the  heart  from 
the  right  and  above  towards  the  left  and  below,  the  apex  of  the 
heart  moves  towards  the  intercostal  space.     The  two  or  three  smaller 

6 


82 


THE   CARDIOGRAM. 


Fig.  2oo. 

Curves  taken  from  the  apex -beat — A,  normal  curve  from  man ;  B,  from  a  clog; 
C,  very  rapid  curve  from  a  dog  ;  D  and  E,  normal  curves  from  a  man,  regis- 
tered on  a  vibrating  glass-plate  where  each  indentation  =  0"01613  sees.  In 
all  the  curves,  a,  h,  means  contraction  of  the  auricles ;  h,  c,  ventricular 
systole ;  d,  closure  of  the  aortic  valves ;  e,  closure  of  the  pulmonary  artery 
valves  ;  e,  f,  relaxation  or  diastole  of  the  ventricle. 


elevations  are  perhaps  caused  by  the  contractions  of  the  ends  of  the 
veins,  the  auricular  appendices,  and  the  atria  themselves. 

Some  observers  ascribe  the  small  elevations  occurring  before  b  to  the  filling  of 
the  ventricle  during  the  diastole,  whereby  it  is  pressed  against  the  intercostal 
space  (Maurer,  Griltzner). 

The  portion,  h,  c,  which  communicates  the  greatest  impulse  to  the 
instrument,  and  also  to  one's  hand  when  it  is  placed  on  the  apex- 
beat,  is  caused  by  the  contraction  of  the  ventricle,  and  during  it  the  first 
sound  of  the  heart  occurs.  Frequently,  but  erroneously,  the  cardiac 
impulse  has  been  ascribed  to  this  contraction  of  the  ventricle.  It 
however,  is  due  to  all  those  conditions  which  cause  an  elevation  in  the 
region  of  the  apex-beat. 


CAUSE    OF    THE    CARDUC   IMPULSE. 


83 


The  cause  of  the  ventriadar  impulse  has  been  much  discussed.  It 
depends  upon  the  following  : — 

(1.)  The  base  of  the  heart  (aiuriculo-ventricular  groove)  represents 
during  diastole  a  transversely-placed  ellipse,  while  during  contraction  it 
has  a  more  circular  figure.  Thus,  the  long  diameter  of  the  ellipse  is 
diminished  in  the  cat  from  28  to  22"5  mm,  (C.  Ludwig) ;  the  small 
diameter  is  increased  {^^J  to  }),  while  the  base  is  brought  nearer  to 
the  chest-wall  (Arnold,  Ludwig) — Fig.  26, 1.  This  alone  does  not  cause 
the  impulse,  but  the  basis  of  the  heart,  being  hardened  during  the 
systole  and  brought  nearer  to  the  chest-wall,  allows  the  apex  to 
execute  the  movement  which  causes  the  impulse. 

(2.)  During  relaxation,  the  ventricle  lies  with  its  apex  obliquely 
downwards,  and  with  its  long  axis  in  an  oblique  direction — so  that  the 
angles  formed  by  the  axis  of  the  ventricles  with  the  diameter  of  the 
base  are  unequal — represents  a  regular  cone,  with  its  axis  at  rigid  angles 
to  its  base.  Hence,  the  apex  must  be  erected  from  below  and  behind, 
forwards  and  upwards  (Harvey — "  cor  sese  erigere "),  and  when 
hardened  during  systole  presses  itself  into  the  intercostal  space 
(Ludwig)— Fig.  20,  II. 


Fig.  26. 
I,  Schematic  horizontal  section  through  the  heart  and  lungs,  and  the  thoracic 
walls,  to  show  the  change  of  shape  which  the  base  of  the  heart  undergoes 
during  contraction  of  the  ventricle — 1,  2,  transverse  diameter  of  the  ventricle 
during  diastole ;  c,  position  of  the  thoracic  wall  during  diastole  ;  a,  b,  trans- 
verse diameter  of  the  heart  during  systole,  with  e,  the  position  of  the  anterior 
thoracic  wall  during  systole.  II,  Side-view  of  the  heart — s,  apex  during 
diastole  ;  p,  the  same  during  systole  (C.  Ludwig). 


84  CAUSE  OF  THE  CARDIAC  IMPULSE. 

(3.)  The  ventricle  undergoes  during  systole  a  slight  spiral  twisting 
on  its  long  axis  ("lateralem  inclinationem" — Harvey),  so  that  the  apex 
is  brought  from  behind  more  forward,  and  thus  a  greater  portion  of  the 
left  ventricle  is  turned  to  the  front.  This  rotation  is  caused  by  the 
muscular  fibres  of  the  ventricles,  which  proceed  from  that  part  of  the 
fibrous  rings  between  the  auricles  and  ventricles  which  lies  next  the 
anterior  thoracic  wall.  The  fibres  pass  from  above  obliquely  down- 
wards, and  to  the  left,  and  also  run  in  part  upon  the  posterior  surface 
of  the  ventricle.  When  they  contract  in  the  axis  of  their  direction, 
they  tend  to  raise  the  apex,  and  also  to  bring  more  of  the  posterior 
surface  of  the  heart  in  relation  with  the  anterior  thoracic  wall  (Harvey, 
Kiirschner,  Wilckens).  This  rotation  is  favoured  by  the  slightly  spiral 
arrangement  of  the  aorta  and  pulmonary  artery  (Kornitzer). 

These  are  the  most  important  causes,  but  minor  causes  are  as 
follows  : — 

(4.)  The  "  reaction  imimlse  "  is  that  movement  which  the  ventricles 
are  said  to  undergo  (like  an  exploded  gun  or  rocket)  at  the  moment 
when  the  blood  is  discharged  into  the  aorta  and  pulmonary  artery, 
whereby  the  apex  goes  in  the  opposite  direction — i.e.,  downwards  and 
slightly  outwards  (Alderson  1825,  Gutbrod,  Skoda,  Hifi'elsheim). 
Landois,  however,  has  shown  that  the  mass  of  blood  is  discharged  into 
the  vessels  0'08  of  a  second  after  the  beginning  of  the  systole,  while 
the  cardiac  impulse  occurs  with  the  first  sound. 

(5.)  When  the  blood  is  discharged  into  the  aorta  and  pulmonary 
artery,  these  vessels  are  slightly  elongated,  owing  to  the  increased  blood- 
pressure  (Senac).  As  the  heart  is  suspended  from  above  by  these 
vessels,  the  apex  is  pressed  slightly  downwards  and  forwards  towards 
the  intercostal  space  (^) 

Guttmann  and  Jahn  observed  that  the  cardiac  impulse  disapj^eared  after  sudden 
Kgature  of  the  aorta  and  pulmonaiy  artery,  while  Chauveau  and  Eosenstein 
maintain  that  it  persists. 

As  the  cardiac  impulse  is  observed  in  the  empty  hearts  of  dead 
animals,  (4)  and  (5)  are  certainly  of  only  second-rate  importance.  Filehne 
and  Pentzoldt  maintain  that  the  apex  duuring  systole  does  not  move  to 
the  left  and  downwards,  as  must  be  the  case  in  (4)  and  (5),  but  that  it 
moves  upwards  and  to  the  right — a  result  corroborated  by  v.  Ziemssen, 
which,  however,  is  disputed  by  Losch. 

It  is  to  be  remembered  that  as  the  apex  is  always  applied  to  the  chest-wall, 
separated  from  it  merely  by  the  thin  margin  of  the  lung,  it  only  presses 
against  the  intercostal  space  during  systole  (Kiwisch). 

After  the  apex  of  the  curve,  c,  has  been  reached  at  the  end  of  the 


THE   TIME   OCCUPIED   BY  THE   CARDIAC   MOVEMENTS.  85 

systole,  the  curve  falls  rapidly,  as  the  ventricle  rapidly  becomes  relaxed. 
In  the  descending  part  of  the  curve,  at  d  and  e,  are  two  elevations, 
which  occur  simultaneously  with  the  second  sound.  These  are  caused  by 
the  sudden  closure  of  the  semi-lunar  valves,  which,  occurring  suddenly, 
is  propagated  through  the  axis  of  the  ventricle  to  its  apex,  and  .thus 
causes  a  vibration  of  the  intercostal  space;  d  corresponds  to  the 
closure  of  the  aortic  valves,  and  e  to  the  closure  of  the  pulmonary 
valves.  The  closure  of  the  valves  in  these  two  vessels  is  not  simul- 
taneous, but  is  separated  by  an  interval  of  0'05  to  0*09  sec.  The 
aortic  valves  close  sooner  on  account  of  the  greater  blood-pressure 
there  (Landois,  187G,  Ott  and  Haas,  Malbranc,  Maurer,  Griitzner, 
Langendorff,  v.  Ziemssen,  and  Ter  Gregorianz). 

Complete  diastolic  relaxation  of  the  ventricle  occurs  from  e  to  /  in 
the  curve.  It  is  clear,  then,  that  the  cardiac  impulse  is  caused  chiefly 
by  the  contraction  of  the  ventricles,  while  the  auricular  systole  and  the 
vibration  caused  by  the  closure  of  the  semi-lunar  valves  are  also  con- 
cerned in  its  production. 

51.  The  Time  Occupied  by  the  Cardiac 
Movements. 

Methods. — The  time  occupied  by  the  various  phases  of  the  movements  of  the 
heart  may  be  determined  by  studying  the  apex -beat  curve. 

(1.)  If  we  know  at  what  rate  the  plate  on  which  the  curve  was  obtained  moved 
during  the  experiment,  of  com'se  all  that  is  necessary  is  to  measure  the  distance, 
and  so  calculate  the  time  occupied  by  any  event  (see  Pulse). 

(2.)  It  is  preferable,  however,  to  cause  a  tuning-fork,  whose  rate  of  vibration 
is  known,  to  write  its  vibrations  under  the  curve  of  the  apex-beat,  or  the 
curve  may  be  written  upon  a  plate  attached  to  a  vibrating  tuning-fork  (Eig. 
25a,  D,  E).  Such  a  curve  contains  fine  teeth,  caused  by  the  vibrations  of  the 
tuning-fork.  D  and  E  are  curves  obtained  from  the  cardiac  impulse  in  this  way 
from  healthy  students.  In  D  the  notch  d,  is  not  indicated.  Each  complete 
vibration  of  tlie  tuning-fork,  reckoned  from  apex  to  apex  of  the  teeth  =  0"01613 
sec,  so  that  it  is  simply  necessary  to  count  the  number  of  teeth  and  multiply  to 
obtain  the  time.     The  values  obtained  vary  within  certain  limits  even  in  health. 

Pause  and  Contraction  of  Auricles.— The  value  of  a  &=pause+con- 
traction  of  the  auricles — is  subject  to  the  greatest  variation,  and  depends 
chiefly  upon  the  number  of  heart-beats  per  minute.  The  more  quickly 
the  heart  beats,  the  smaller  is  the  pause,  and  conversely.  In  some 
curves,  even  when  the  heart  beats  slowly,  it  is  scarcely  possible  to 
distinguish  the  auricular  contraction  (indicated  by  a  rise)  from  the 
part  of  the  curve  corresponding  to  the  pause  (indicated  by  a  horizontal 
line).  In  one  case  (heart-beats  55  per  minute)  the  pause  =  0*4  sec,  the 
auricular  contraction  =  0 "17 7  sec.  In  Fig.  25a,  A,  the  time  occupied  by 
the  pause  +  the  auricular  contraction  (74  beats  per  minute)  =  0'5  sec. 


86  TIME   OCCUPIED   BY  THE  VENTRICULAR  SYSTOLE. 

In  D  the  a  &  =  19  to  20  vibrations  =  0' 3 2  sec;  in  E  =  26  vibrations 
=  0*42  sec. 

Ventricular  Systole. — The  ventricular  systole  is  calculated  from  the 
beginning  of  the  contraction,  h  to  e,  when  the  semi-lunar  valves  are 
closed ;  it  lasts  from  the  first  to  the  second  sound.  It  also  varies 
somewhat,  but  is  more  constant.  When  the  heart  beats  rapidly,  it  is 
somewhat  less — during  slow  action,  greater.  In  E  =  0*32  sec;  in  D 
=  0"29  sec  ;  with  55  beats  per  minute  Landois  found  it=0"34,  with  a 
very  high  rate  of  beating  =  0  •199  sec. 

When  the  ventricle  beats  feebly,  it  contracts  more  slowly,  as  can  be  shown  by 
ajiplying  the  registering  apparatus  to  the  heart  of  an  animal  just  killed.  In  Fig. 
27,  from  the  ventricle  of  a  rabbit  just  killed,  the  slow  heart-beats,  B,  are  seen  to 
last  longest. 

A  B 


Fig.  27. 

Curves  obtained  from  the  veatricle  of  a  rabbit,  and  written  upon  a  vibrating  plate 
attached  to  a  tuning-fork  (vibration=:0'01613  sec.) — A,  tolerably  soon  after 
death ;   B,  from  the  dying  ventricle. 

In  calculating  the  time  occupied  by  the  ventricular  systole  we  must  remember — 
(1.)  The  time  between  the  two  sounds  of  the  heart,  i.e.,  from  the  beginning  of  the 
first  to  the  end  of  the  second  sound  (h  to  e).  (2.)  The  time  the  hloodfloios  into  the 
aorta,  which  comes  to  an  end  at  the  depression  between  c  and  d  (in  Fig.  25a,  E). 
Its  commencement,  however,  does  not  coincide  wdth  h,  as  the  aortic  valves  open 
0'085  (Landois)  to  0'073  (Rive)  sec.  after  the  beginning  of  the  ventricular  systole. 
Hence  the  aortic  current  lasts  O'OS  to  0'09  sec. 

This  is  calculated  in  the  following  way : — The  time  between  the  first  sound  of 
the  heart  and  the  pulse  in  the  axillary  artery  is  0"137  sec,  and  of  this  time  0'052 
sec.  arc  occupied  in  the  propagation  of  the  pulse-wave  along  the  30  cm.  of  artery 
lying  between  the  root  of  the  aorta  and  the  axilla.  Thus  the  pulse-wave  in  the 
aorta  occurs  0'137  minus  0'052  =  0'085  sec.  after  the  beginning  of  the  first  sound. 

The  current  in  the  pulmonary  artery  is  interrupted  in  the  depression  between 
d  and  e.  (3.)  Lastly,  the  time  occupied  hy  the  muscular  contraction  of  the 
ventricle,  which  begins  at  h,  reaches  its  greatest  extent  at  c,  and  is  completely 
relaxed  at  /.  The  apex  of  the  curve,  c,  may  be  higher  or  lower  according  to  the 
flexibility  of  the  intercostal  space,  hence  the  position  of  c  varies.  In  hypertrophy 
with  dilatation  of  the  left  ventricle,  the  duration  of  the  ventricular  contraction 
does  not  greatly  exceed  the  normal. 

The  time  Avhich  elapses  between  d  and  e,  i.e.,  between  the  complete 
closure  of  the  aortic  and  pulmonary  valves,  is  greater  the  more  the 
pressure  in  the  aorta  exceeds  that  in  the  pulmonary  artery,  as  the 


ENDOCARDIAL  PRESSURE. 


87 


valves  arc  closed  by  the  pressure  from  above,  and  the  difFerence  in 
time  may  bo  0"05  sec,  or  oven  double  that  time,  in  which  case  the 
second  sound  appears  double  (compare  p.  94).  If  the  aortic  pressure 
diminishes  while  that  in  the  pulmonary  artery  rises,  d  and  e  may 
be  so  near  each  other  that  they  are  no  longer  marked  as  distinct 
elements  in  the  curve. 

The  time,  e,/,  during  which  the  ventricle  relaxes  varies  somewhat: 
0"1  sec.  may  be  taken  as  a  mean. 

Accelerated  Cardiac  Action. — When  the  caction  of  the  heart  is  greatly 
accelerated,  the  pause  is  considerably  shortened  in  the  first  instance  (Bonders), 
and  to  a  less  extent  the  time  of  contraction  of  the  auricles  aud  ventricles.  When 
the  jiulse-rate  is  very  rapid,  the  systole  of  the  atria  coincides  with  the  closure  of 
the  arterial  valves  of  the  preceding  contraction,  as  is  shown  in  Fig.  25a,  C  (dog). 

In  registering  the  cardiac  impulse,  the  apparatus  is  separated  Ijy  a  greater  or 
less  extent  of  soft  parts  from  the  heart  itself,  so  that  in  all  eases  the  intercostal 
tissues  do  not  follow  exactly  the  movements  of  the  heart,  and  thus  the  curve 
obtained  may  not  coincide  mathematically  with  the  movemeuts  of  the  heart.  It 
is  desirable  that  curves  be  obtained  from  persons  whose  hearts  are  exposed,  i.e., 
in  cases  of  ectopia  cordis. 

Gibson  inscribed  cardiograms   from   the   heart  of  a  man  with   cleft  sternum. 
The  following  were  the  results  obtained: — Auricular  contraction  =  0"115;  ventri- 
cular contraction  (/;,(Z)  =  0"28 ;  difference  between  closure  of  valves  (fZ,  e)  =  0"09 
ventricular  diastole  (e,/)  =  O'll ;  pause  =  0 "45  sec. 

Endocardial  Pressure. — In  large  mammals,  such  as  the  horse, 
Chauveau  and  Marey  determined 
the  duration  of  the  events  that 
occur  within  the  heart,  and  also 
the  endocardial  pressure,  by 
means  of  a  cardiac  sound.  Small 
elastic  bags  attached  to  tubes 
were  introduced  through  the 
jugular  vein  into  the  right  auricle 
and  ventricle.  Each  of  these 
tubes  was  connected  with  a  regis- 
tering tambour  (Fig.  28),  and 
simultaneous  tracings  of  the  varia-  Fig.  28. 

tions  of  pressure  within  the  cavi-    Marey's  registering  tambour,  consisting  of 


ties  of  the  heart  were  obtained 
by  causing  the  writing-points  of 
the  levers  of  the  tambours  to 
write  upon  a  revolving  cylinder. 


a  metallic  capsule,  T,  with  thin  india- 
rubber  stretched  over  it,  and  bearing 
an  aluminium  disc,  which  acts  upon 
the  writing  lever,  H.  By  means  of  a 
thick-walled  caoutchouc  tube,  it  may 
be  connected  with  any  system  con- 
taining air,  so  as  to  record  variations 
of  pressure. 


Fig.  29,  A,  gives  the  result  obtained 
when  the  elastic  bag  was  placed  in 
the  right  auricle,  introduced  through 
the  jugular  vein  and  superior  vena  cava;  B,  when  it  was  pushed  through  the 
tricuspid  valve  into  the  right  ventricle ;  D,  in  the  root  of  the  aorta,   pushed  in 


88 


ENDOCARDIAL  PRESSURE. 


through  the  carotid ;  C,  pushed  past  the  semi-lunar  valves  into  the  left  ventricle ; 
while  at  E  a  similar  bag  has  been  placed  externally  between  the  heart's  apex 
and  the  inner  wall  of  the  chest.  In  all  cases  -y= auricular  contraction;  V,  that  of 
the  ventricle;  s,  closure  of  semi-lunar  valves,  sooner  in  C  than  B;  P  =  pause. 

Method, — The  cardiac  sound  consists  of  a  tube  containing  two  separate  air- 
passages,  and  ui  connection  with  each  of  these  there  is  a  small  elastic  bag  or 
ampulla.  One  of  the  bags  is  fixed  to  the  free  end  of  the  sound,  and  communicates 
Avith  one  of  the  air-passages.  The  other  bag  is  i)laced  in  connection  with  the 
second  air-passage  in  the  sound,  and  at  such  a  distance,  that,  when  the  former  bag 
lies  Avithin  the  ventricle,  the  latter  is  in  the  auricle.  Each  bag  and  air-tube  in 
connection  "with  it,  is  connected  with  a  Marey's  tambour,  Fig.  28,  provided  with  a 
lever  which  inscribes  its  movements  upon  a  revolving  cylinder.  Any  variation 
of  pressure  within  the  auricle  or  ventricle  will  affect  the  elastic  ampullEe,  and  thus 
raise  or  depress  the  lever.  Care  must  be  taken  that  the  writing-points  of  the 
levers,  are  placed  exactly  above  each  other.  A  tracing  of  the  cardiac  impulse  is 
taken  simultaneously  by  means  of  a  cardiograph  attached  to  a  separate  tambour. 

It  has  still  to  be  determined  whether  the  auricles  and  ventricles  act 
alternately,  so  that  at  the  moment  of  the  beginning  of  the  ventricular 


Bight  Auricle. 


Eight  Ventricle. 


Left  Ventricle. 


Aorta. 


■  Cardiac  Impulse, 


Fig.  29, 

Curves  obtained  from  the  heart  by  the  cardiac  sound  (Chauveau  and  Marey). 


PATHOLOGICAL   DISTURBANCES   OF  THE   CARDIAC   IMPULSE.         89 

contraction  the  auricles  relax,  or  whether  the  ventricles  are  contracted 
wliile  the  auricles  still  remain  slightly  contracted,  so  that  the  whole 
heart  is  contracted  for  a  short  time  at  least.  The  latter  view  was 
supported  by  Harvey,  Bonders,  Schiff,  and  others,  while  Haller  and 
many  of  the  more  recent  observers  support  the  view  that  the  action  of 
the  auricles  and  ventricles  alternates.  In  the  case  of  Frau  Serafin, 
whose  heart  was  exposed,  v.  Ziemssen  and  Ter  Gregorianz  obtained 
curves  from  the  auricles,  which  showed  that  the  contraction  of  the 
auricles  continued  even  after  the  commencement  of  the  ventricular 
systole.  In  Marey's  curve  (Fig.  29)  the  contraction  of  the  ventricle  is 
represented  as  following  that  of  the  auricle. 

52.  Pathological  Disturbances  of  the  Cardiac 
Impulse. 

Change  in  the  Position  of  the  Apex-beat. — The  position  of  the  cardiac 

impulse  is  changed — (1)  by  the  accumulation  of  fliiids  (serum,  pus,  blood)  or  gas 
in  one  pleural  cavity.  A  copious  effusion  into  the  left  pleural  cavity  compresses 
the  lung,  and  may  displace  the  heart  towards  the  right  side,  while  effusion  on  the 
right  side  may  push  the  heart  more  to  the  left.  As  the  right  heart  must  make 
a  greater  effort  to  propel  the  blood  through  the  compressed  lung,  the  cardiac 
impulse  is  usually  increased.  Advanced  emphysema  of  the  lung,  causing  the 
diaphragm  to  be  pressed  downwards,  displaces  the  heart  downwards  and  inwards, 
while  conversely  the  pushing  or  pulling  up  of  the  diaphragm  (by  contraction  of 
the  lung,  or  through  pressure  from  below)  causes  the  apex-beat  to  be  displaced 
upwards  (even  to  the  third  intercostal  space),  and  also  slightly  to  the  left. 
Thickening  of  the  muscular  walls  and  dilatation  of  the  cavities  (hypertrophy  with 
dilatation)  of  the  left  ventricle  make  that  ventricle  longer  and  broader,  while  the 
increased  cardiac  impulse  may  be  felt  to  the  left  of  the  mammaiy  line,  and 
in  the  axillary  line  in  the  sixth,  seventh,  or  even  eighth  intercostal  space. 
Hypertrophy,  with  dilatation  of  the  right  side,  increases  the  breadth  of  the  heart, 
while  the  cardiac  impulse  is  felt  more  to  the  right,  even  to  the  right  of  the 
sternum,  and  at  the  same  time  it  may  be  slightly  beyond  the  left  mammary 
line.  In  the  rare  cases  where  the  heart  is  transposed,  the  apex-beat  is  felt  on 
the  right  side.  When  the  cardiac  impulse  goes  to  the  left  of  the  left  mammary 
line,  or  to  the  right  of  the  parasternal  line,  the  heart  is  increased  in  breadth,  and 
there  is  hypertrophy  of  the  heart.  A  greatly  increased  cardiac  unpulse  may 
extend  to  several  intercostal  spaces. 

The  cardiac  impulse  is  abnormally  tceakened  during  atrophy  and  degeneration 
of  the  cardiac  muscle,  or  by  weakening  of  the  innervation  of  the  cardiac  gangha. 
It  is  also  weakened  when  the  heart  is  separated  from  the  chest-wall  owing  to  the 
collection  of  fluids  or  air  in  the  pericardium,  or  by  a  greatly  distended  left  lung  ; 
and,  indeed,  when  the  left  side  of  the  chest  is  filled  with  fluid,  the  cardiac  impulse 
may  be  extinguished.  The  same  occurs  when  the  left  ventricle  is  very  imperfectly 
tilled  during  its  contraction  (in  consequence  of  marked  narrowing  of  the  mitral 
orifice),  or  when  it  can  only  empty  itself  very  slowly  and  gradually,  as  during 
marked  narrowing  of  the  aortic  orifice. 

An  increase  of  the  cardiac  impulse  occm-s  during  hypertrophy  of  the  walls,  as 
well  as  after  the  influence  of  various  stimuli  (psychical,  inflammatory,  febrile, 
toxic)  which  affect  the  cardiac  ganglia.     Great  hypertrophy  of  the  left  ventricle 


90 


VARIATIONS   OF  THE  CARDIAC  IMPULSE. 


causes  the  heart  to  heave,  so  that  a  part  of  the  left  chest-wall  may  be  raised  and 
also  vibrate  during  systole. 

A  falling  in  of  the  anterior  wall  of  the  chest  during  cardiac  systole  occurs  in  the 
third  and  fourth  interspaces,  not  unfrequently  under  normal  circumstances, 
sometimes  during  increased  cardiac  action,  and  in  eccentric  hypertrophy  of  the  ven- 
tricles. As  the  heart's  apex  is  slightly  displaced,  and  the  ventricle  becomes  slightly 
smaller  during  its  systole,  the  empty  space  is  filled  by  the  yielding  soft  parts  of 
the  intercostal  space.  When  the  heart  is  united  with  the  pericardium  and  the 
surrounding  connective  tissue,  which  renders  systolic  locomotion  of  the  heart 
impossible,  a  falling  in  of  the  chest-wall  during  systole  takes  the  place  of  the 
cardiac  impulse  (Skoda).  During  the  diastole  a  diastolic  cardiac  impulse  of  the 
corresponding  part  of  the  chest- wall  may  be  said  to  occur. 

Changes  in  the  cardiac  impulse  are  best  ascertained  by  taking  graphic  repre- 
sentations of  the  cardiac  impulse,  and  studying  the  curves  so  obtained.  This 
method  has  been  largely  followed  by  many  clinicians. 

In  all  the  following  curves,  a,  h,  means  auricular  contraction ;  b,  c,  ventricular 


Fig.  30. 
Various  forms  of  curves  obtained  from  the  cardiac  impulse — a,  h,  Contraction  of 
auricles ;  h,  c,  ventricular  systole ;  d,  closure  of  aortic,  and  'e  of  pulmonary 
valves ;  e,  /,  diastole  of  ventricle  ;  P,  Q,  hypertrophy  and  dilatation  of  the 
left  ventricle;  E,  stenosis  of  the  aortic  orifice;  F,  mitral  insufficiency;  G, 
mitral  stenosis ;  L,  nervous  palpitation  in  Basedow's  disease ;  M,  case  of 
so-called  hemisystole. 


THE  HEART-SOUNDS.  91 

contraction;   d,  closure  of  the  aortic  valves,  and  e  of  the  pulmonary;   e, /,  the 
time  the  ventricle  is  relaxed  (Fig.  30.) 

In  curve  P  (much  reduced),  taken  from  a  case  of  marked  hypertrophy  vnth. 
dilatation,  the  ventricular  contraction,  h  c,  is  usually  very  great,  while  the  time 
occupied  by  the  contraction  is  not  much  increased.  P  and  Q  vi^ere  obtained  from 
a  man  suffering  from  marked  eccentric  hypertrophy  of  the  left  ventricle,  in  con- 
sequence of  insufficiency  of  the  aortic  valves.  Curve  Q  was  taken  intentionally 
over  the  auriculo-ventricular  groove,  where  a  falling  in  of  the  chest-wall  occurred 
during  systole ;  nevertheless,  the  individual  events  occurring  in  the  heart  are 
indicated. 

Fig.  E  is  from  a  case  of  aortic  stenosis.  The  auricular  contraction  (a,  h)  lasts 
only  a  short  time ;  the  ventricular  systole  is  obviously  lengthened,  and  after  a 
short  elevation  (h,  c)  shows  a  series  of  fine  indentations  (c,  e)  caused  by  the  blood 
being  pressed  through  the  narrowed  and  roughened  aorta. 

Fig.  F,  from  a  case  of  insufficiency  of  the  mitral  valve,  shows  {a,  h)  well  marked 
on  account  of  the  increased  activity  of  the  left  auricle,  while  the  shock  (d)  from 
the  closure  of  the  aortic  valves  is  small  on  account  of  the  diminished  tension  in 
the  arterial  system.  On  the  other  hand,  the  shock  from  the  accentuated  pul- 
monary sound  (e)  is  very  great,  and  is  in  the  apex  of  the  curve.  On  account  of 
the  great  tension  in  the  pulmonary  artery,  the  second  pulmonary  tone  may  be  so 
strong,  and  succeed  the  second  aortic  sound  (d)  so  rapidly,  that  both  almost  merge 
completely  into  each  other  (H  and  K). 

The  curve  of  stenosis  of  the  mitral  orijice  (G)  shows  a  long  irregular  notched 
auricular  contraction  {a,  h)  caused  by  the  blood  being  forced  through  an  irregular 
narrow  orifice.  The  ventricular  contraction  (6,  c)  is  feeble  on  account  of  its  being 
imperfectly  filled.  The  closures  of  the  two  valves,  d  and  e,  are  relatively  far  apart, 
and  one  can  hear  distinctly  a  reduplicated  second  sound.  The  aortic  valves  close 
rapidly  because  the  aorta  is  imperfectly  supplied  with  blood,  while  the  more 
copious  inflow  of  blood  into  the  pulmonary  artery  causes  a  later  contraction  of  its 
valves  (Geigel). 

If  the  heart  beats  rapidly  and  feebly — if  the  blood-pressure  in  the  aorta  and 
pulmonary  artery  be  low,  the  signs  of  closure  of  the  pulmonary  valves  may  be 
absent — as  in  curve  L — taken  from  a  girl  suffering  from  nervous  palpitation  and 
morbus  Basedowii. 

In  very  rare  cases  of  insufficiency  of  the  mitral  valve,  it  has  been  observed  that 
at  certain  times  both  ventricles  contract  simultaneously,  as  in  a  normal  heart,  but 
that  this  alternates  with  a  condition  where  the  right  ventricle  alone  seems  to  con- 
tract. Curve  M  is  such  a  curve  obtained  by  Malbranc,  who  called  this  condition 
intermittent  hemisystole.  The  first  curve  (I)  is  like  a  normal  curve,  during  which 
the  whole  heart  acted  as  usual.  The  curve  II,  however,  is  caused  by  the  right 
side  of  the  heart  alone ;  it  wants  the  closure  of  the  aortic  valves,  d,  and  there  was 
no  pulse  in  the  arteries.  Owing  to  insufficiency  of  the  tricuspid  valve,  the  same 
person  had  a  venous  pulse  with  every  cardiac  impulse,  so  that  the  arterial  and 
venous  pulses  first  occurred  together,  and  then  the  venous  pulse  alone  occurred. 

In  these  cases  (Skoda,  v.  Bamberger,  Leyden)  the  mitral  insufficiency  leads  to 
overflowing  of  the  right  ventricle,  while  the  left  is  nearly  empty,  so  that  the  right 
side  requires  to  contract  more  energetically  than  the  left.  It  does  not  seem  that 
the  right  ventricle  alone  contracts  in  these  cases,  but  rather  that  the  action  of  the 
left  side  is  very  feeble. 

53.  The  Heart-Sounds. 

On  listening  over  the  region  of  the  heart  in  a  healthy  man,  either 
with  the  ear  applied  directly  to  the  chest-wall,  or  by  means  of  a 


92  THE  HEART-SOUNDS. 

stethoscope  (Laennec,  1819),  we  hear  two  characteristic  sounds,  the 
so-called  "  heart-sounds."  Harvey  was  acquainted  with  these  sounds, 
but  they  have  been  more  carefully  studied  by  clinicians  since  the  time 
of  Laennec. 

The  first  sound  [long  or  systolic]  is  somewhat  duller,  longer,  and 
one-third  or  one-fourth  deeper,  than  the  second  sound;  it  is  less  sharply 
defined  at  first,  and  is  isochronous  ivith  the  systole  of  the  ventricles  (Turnerj. 
The  second  sound  [short  or  diastolic]  is  clearer,  sharper,  shorter,  more 
sudden,  and  is  one-third  to  one-fourth  higher ;  it  is  sharply  defined  and 
isochronous  with  the  closure  of  the  semi-lunar  valves.  There  is  a  very 
short  interval  between  the  first  and  second  sounds,  and  between  the 
second  and  the  next  following  first  sound  a  distinctly  longer  interval. 
This  is  the  pause. 

[The  sounds  emitted  during  each  cardiac  cycle  have  been  compared 
to  the  pronunciation  of  the  syllables  lulh,  dwp.  We  may  express  the 
course  of  events  with  reference  to  the  sounds,  thus : — lubb,  diip,  pause.'] 
Or  the  result  may  be  expressed  thus — 

V  V    

"^~~|to  ^fe=f=^^|=^3;E^^ 


si- 


i    ^ 


i-  ^ 


-ii- 


Bu     -      tup.  Bu      -      tup. 

The  causes  of  the  first  sound  are  due  to  two  conditions.  As  the 
sound  is  heard  in  an  excised  heart  in  which  the  movements  of  the 
valves  are  arrested,  and  also  when  the  finger  is  introduced  into  the 
auriculo-ventricular  orifices  so  as  to  prevent  the  closure  of  the  valves 
(0.  Ludwig  and  Dogiel),  one  of  the  chief  factors  lies  in  the  "  muscle- 
sound  "  produced  by  the  contracting  muscular  fibres  of  the  ventricles 
(Williams,  1835). 

This  sound  is  supported  and  increased  by  the  sound  produced  by  the 
tension  and  vibration  of  the  auriculo-ventricular  valves  and  their 
chordae  tendinise,  at  the  moment  of  the  ventricular  systole  (Rouanet, 
Kiwisch,  Bayer,  Giese). 

Wintrich,  by  means  of  proper  resonators,  has  been  able  so  to  analyse 
the  first  sound  as  to  distinguish  the  clear,  short,  valvular  part  from  the 
deep,  long,  muscular  sound. 

The  muscle-sound  produced  by  transversely-striped  muscle  does  not  occur  with  a 
simple  contraction,  but  only  when  several  contractions  are  superposed  to  produce 
tetanus  (see  Muscle).  The  ventricular  contraction  is  only  a  simple  contraction, 
but  it  lasts  considerably  longer  than  the  contraction  of  other  muscles,  and  herein 
lies  the  cause  of  the  occurrence  of  the  muscle-sound  during  the  ventricular  con- 
traction. 

Defective  Heart-Sounds. — In  certain  conditions  (typhus,  fatty  degeneration 
of  the  heart)  where  the  muscular  substance  of  the  heart  is  much  weakened,  the 


THE   HEART-SOUNDS. 


93 


Fig.  31. 

The  heart— its  several  parts  and  gi-eat  vessels  in  relation  to  the  front  of  the 
thorax.  The  lungs  are  collapsed  to  their  normal  extent,  as  after  death, 
exposing  the  heart.  The  outlines  of  the  several  parts  of  the  heart  are  indi- 
cated by  very  line  dotted  lines.  The  area  of  propagation  of  valvular  murmurs 
is  marked  out  by  more  visible  dotted  lines.  A,  the  circle  of  mitral  murmur, 
corresponds  to  tlie  left  apex.  The  broad  and  somewhat  diffused  area,  roughly 
triangular,  is  the  region  of  tricuspid  murmurs,  and  corresponds  generally  ■with 
the  right  ventricle,  where  it  is  least  covered  by  lung.  The  letter  C  is  in  its 
centre.  The  circumscribed  circular  area,  D,  is  the  part  over  which  the  pulmonic 
arterial  murmurs  are  commonly  heard  loudest.  In  many  cases  it  is  an  inch, 
or  even  more,  lower  do-\vn,  correspondmg  to  the  conus  arteriosus  of  the  right 
venti'icle,  where  it  touches  the  walls  of  the  thorax.  The  internal  organs  and 
parts  of  organs  are  indicated  by  letters  as  follows — r.  au,  right  auricle, 
traced  in  fine  dotting ;  ao,  arch  of  aorta,  seen  in  the  first  intercostal  sjjace, 
and  traced  m  fine  dotting  on  the  sternum ;  vi,  the  t\\o  innominate  veins ; 
rv,  right  ventricle  ;  h\  left  ventricle. 


94  CAUSES   OF   THE    HEART-SOUNDS. 

first  sound  may  be  completely  inaudible.  In  aortic  insufficiency,  in  which,  in  con- 
sequence of  the  reflux  of  blood  from  the  aorta  into  the  ventricle,  the  mitral  valve 
is  gradually  stretched,  and  sometimes  even  before  the  beginning  of  the  ventricular 
systole,  the  first  sound  may  be  absent.  Both  pathological  cases  show  that  for  the 
production  of  the  first  sound,  muscle-sound  and  valve-sound  must  eventually 
work  together,  and  that  the  tone  is  altered,  or  may  even  disappear,  when  one  of 
these  causes  is  absent. 

The  Cause  of  the  Second  Sound  is  undoubtedly  due  to  the  prompt 
closure,  and  therefore  sudden  stretching  or  tension,  of  the  semi-lunar 
valves  of  the  aorta  and  pulmonary  artery,  so  that  it  is  purely  a  valvular 
sound  (Carswell  and  Eouanet,  1830).  Perhaps  it  is  augmented  by  the 
sudden  vibration  of  the  fluid-particles  in  the  large  arterial  trunks.  As 
already  pointed  out  (p.  85),  the  aortic  and  pulmonary  valves  do  not 
close  simultaneously.  Usually,  however,  the  difference  in  time  is  so 
small  that  both  valves  make  one  sound,  but  the  second  sound  may  be 
double  or  divided  when,  through  increase  of  the  difference  of  pressure 
in  the  aorta  and  pulmonary  artery,  the  interval  becomes  longer.  Even 
in  health  this  may  be  the  case,  as  occurs  at  the  end  of  inspiration  or 
the  beginning  of  expiration  (v.  Dusch). 

[The  second  sound  has  all  the  characters  of  a  valvular  sound.  That 
the  aortic  valves  are  concerned  in  its  production,  is  proved  by  intro- 
ducing a  curved  wire  through  the  left  carotid  artery  and  hooking  up 
one  or  more  segments  of  the  valve,  when  the  sound  is  modified,  and  it 
may  be  replaced  by  an  abnormal  sound  or  "  murmur."  Again,  when 
these  valves  are  diseased,  the  sound  is  altered,  and  it  may  be  accompanied 
or  even  displaced  by  murmurs.] 

Where  the  Sounds  are  Heard  Loudest. — The  sound  produced  by  the 
tricuspid  valve  is  heard  loudest  at  the  insertion  of  the  fifth  light  rib  into 
the  sternum,  and  from  here  somewhat  inwards  and  obliquely  upwards 
along  the  sternum;  as  the  mitral  valve  lies  more  to  the  left  and  deeper 
in  the  chest,  and  is  covered  in  front  by  the  arterial  orifice,  the  mitral 
sound  is  best  heard  at  the  apex-beat,  or  immediately  above  it,  wdiere  a 
strip  of  the  left  ventricle  lies  next  the  chest-wall.  [The  sound  is  con- 
ducted to  the  part  nearest  the  ear  of  the  listener  by  the  muscular 
substance  of  the  heart.]  The  aortic  and  pulmonary  orifices  lie  so 
close  together  that  it  is  convenient  to  listen  for  the  second  [aortic) 
sound  in  the  direction  of  the  aorta  and  where  it  comes  nearest  to 
the  surface,  i.e.,  over  the  first  right  costal  cartilage  close  to'  its 
junction  Avith  the  sternum.  The  sound,  although  produced  at  the 
semi-lunar  valves,  is  carried  upwards  by  the  column  of  blood  and 
by  the  walls  of  the  aorta. 

The  sound  produced  by  the  pulmonary  artery  is  heard  most  distinctly 
in  the  second  left  intercostal  space,  somewhat  to  the  left  and  external 
to  the  margin  of  the  sternum  (Fig.  31). 


VARIATIONS   OF  THE   HEART-SOUNDS.  95 


54.  Variations  of  the  Heart- Sounds. 

An  increase  of  the  firsfc  sound  of  both  ventricles  indicates  a  more  energetic  con- 
traction of  the  ventricular  muscle  and  a  simultaneously  greater  and  more  sudden 
tension  of  the  auriculo-ventricular  valves.  An  increase  of  the  second  sound  is  a 
sign  of  inci-eased  tension  in  the  interior  of  the  corresponding  large  arteries. 
Hence,  increase  of  the  second  (pulmonary)  sound  indicates  overfilling  and  excessive 
tension  in  the  pulmonary  circuit. 

Feeble  weak  action  of  the  heart,  as  well  as  abnormal  want  of  blood  in  the  heart, 
causes  weak  heart-sounds,  which  is  the  case  in  degenerations  of  the  heart-muscle. 

Irregularities  in  structure  of  the  individual  valves  may  cause  the  heart-sounds 
to  become  '■'■impure.'''  If  a  pathological  cavity,  filled  with  air,  be  so  placed,  and 
of  such  a  form  as  to  act  as  a  resonator  to  the  heart-sounds,  they  may  assume  a 
"metallic"  character.  The  first  and  second  sounds  may  be  "reduplicated"  or 
"divided."  The  reduplication  of  the  first  sound  is  explained  by  the  tension 
of  the  tricuspid  and  that  of  the  mitral  valves  not  occurring  simultaneously. 
Sometimes  a  soimd  is  produced  by  a  hypertrophied  auricle  producing  an  audible 
presystolic  sound,  i.e.,  a  sound  or  "murmur,"  preceding  the  first  sound.  As  the 
aortic  and  pulmonary  valves  do  not  close  quite  simultaneously,  a  reduplicated 
second  sound  is  only  an  increase  of  a  physiological  condition  (Landois).  All  con- 
ditions which  cause  the  aortic  valves  to  close  rapidly  (diminished  amount  of  blood 
in  the  left  ventricle)  and  the  pulmonary  valves  to  close  later  (congestion  of  the 
right  ventricle— both  conditions  together  in  mitral  stenosis),  favour  the  production 
of  a  reduplicated  second  sound. 

Cardiac  Murmurs.— if  irregularities  occur  in  the  valves,  either  in  cases  of  stenosis 
or  in  insufficiency,  so  chat  the  blood  is  subjected  to  vibratory  oscillations  and  friction, 
then,  instead  of  the  heart-sounds,  other  sounds  arise  or  accompany  these — murmurs 
or  bruits,  which,  when  combined,  are  always  accompanied  by  disturbances  of  the 
circulation.  It  is  rare  that  tumours  or  other  deposits  projecting  into  the  ventricles 
cause  murmurs,  unless  there  he  present  at  the  same  time  lesions  of  the  valves  and 
disturbances  of  the  circulation.  The  cardiac  murmurs  or  bruits  are  always  related 
to  the  systole  or  diastole,  and  usually  the  systolic  are  more  accentuated  and 
louder.  Sometimes  they  are  so  loud  that  the  thorax  trembles  under  their  irregular 
oscillations  (fremitus,  frt^missement  cataire). 

In  cases  where  diastolic  murmurs  are  heard,  there  are  always  anatomical  changes 
in  the  cardiac  mechanism.  These  are  insufficiency  of  the  arterial  valves,  or  stenosis 
of  the  auriculo-ventricular  orifices  (usually  the  left).  Systolic  murmurs  do 
not  always  necessitate  a  disturbance  in  the  cardiac  mechanism.  They  may 
occur  in  the  left  side,  owing  to  insufficiency  of  the  mitral  valve,  stenosis  of 
the  aorta,  and  in  calcification  and  dilatation  of  the  ascending  part  of  the  aorta. 
These  murmurs  occur  very  much  less  frequently  on  the  right  side,  and  are  due  to 
insufficiency  of  the  tricuspid  and  stenosis  of  the  pulmonary  orifice. 

Systolic  munnurs  often  occur  without  any  valvular  lesion,  although  they  are 
always  less  loud,  and  are  caused  by  abnormal  vibrations  of  the  valves  or  arterial 
walls.  They  occur  most  frequently  at  the  orifice  of  the  pulmonary  artery,  less 
frequently  at  the  mitral,  and  still  less  frequently  at  the  aorta  or  the  tricuspid 
orifice.  Anaemia,  general  mal-nutrition,  acute  febrile  affections,  are  the  causes  of 
these  murmurs. 

Murmurs  also  occur  during  a  certain  stage  of  inflammation  of  the  pericardium 
(pericarditis)  from  the  roughened  surfaces  of  this  membrane  rubbing  upon  each 
other.  Audible  friction-sounds  are  thus  produced,  and  the  vibration  may  even  be 
perceptible  to  touch.  [These  are  ' '  friction-sounds, "  and  quite  distinct  from  sounds 
produced  within  the  heart  itself.] 


96       DURATION  OF  THE  MOVEMENTS  OF  THE  HEART, 

55.  Duration  of  the  Movements  of  the  Heart. 

That  the  heart  continues  to  beat  for  some  time  after  it  is  cut  out 
of  the  body,  was  known  to  Cleanthes,  a  contemporary  of  Herophilus, 
300  B.C.  The  movement  lasts  longer  in  cold-blooded  animals  (frog, 
turtle,  fish) — extending  even  to  days — than  in  mammals.  A  rabbit's  heart 
beats  from  3  minutes  up  to  36  minutes  after  it  is  cut  out  of  the  body. 
The  average  of  many  experiments  is  about  11  minutes.  Panum  found 
the  last  trace  of  contraction  to  occur  in  the  right  auricle  (rabbit) 
15  hours  after  death;  in  a  mouse's  heart,  46  hours;  in  a  dog's,  96  hours. 
An  excised  frog's  heart  beats,  at  the  longest,  2|-  days  (Valentin).  In 
a  human  embryo  (third  month)  the  heart  was  found  beating  after 
4  hours.  In  this  condition  stimulation  causes  an  increase  and  accelera- 
tion of  the  action.  Afterwards,  the  ventricular  contraction  first  becomes 
weaker,  and  soon  each  auricular  contraction  is  not  followed  by  a 
ventricular  contraction,  two  or  more  of  the  former  being  succeeded  by 
only  one  of  the  latter.  At  the  same  time  the  ventricles  contract  more 
slowly  (Fig.  27),  and  soon  stop  altogether,  while  the  auricles  still  con- 
tinue to  beat.  If  the  ventricles  be  stimulated  directly,  as  by  pricking 
them  with  a  pin,  they  may  execute  a  contraction.  The  left  auricle 
soon  ceases  to  beat,  while  the  right  auricle  still  continues  to  contract. 
The  right  auricular  appendage  continues  to  beat  longest,  as  was 
observed  by  Galen  and  Cardanus  (1550).  The  term  "ultimum 
moriens  "  is  applied  to  it.  Similar  observations  have  been  made  upon 
the  hearts  of  persons  who  have  been  executed. 

If  the  heart  has  ceased  to  beat,  it  may  be  excited  to  contract  for  a 
short  time  by  direct  stimulation  (Harvey),  more  especially  by  heat ; 
even  under  these  circumstances,  the  auricles  and  their  appendages  are 
the  last  parts  to  cease  contracting.  As  a  general  rule,  direct  stimula- 
tion, although  it  may  cause  the  heart  to  act  more  vigorously  for  a 
short  time,  brings  it  to  rest  sooner.  In  such  cases,  therefore,  the 
regular  sequence  of  events  ceases,  and  there  is  usually  a  twitching 
movement  of  the  muscular  fibres  of  the  heart.  C.  Ludwig  found  that 
even  after  the  excitability  is  extinguished  in  the  mammalian  heart,  it 
may  be  restored  by  injecting  arterial  blood  into  the  coronary  arteries : 
lesion  of  these  vessels  is  followed  by  enfeebled  action  of  the  heart 
(p.  75).  Hammer  found  that  in  a  man,  whose  left  coronary  artery  was 
plugged,  the  pulse  fell  from  80  to  8  beats  ^er  minute. 

Action  of  Gases  on  the  Heart. — During  its  activity  the  heart  uses 
0,  and  produces  COg,  so  that  it  beats  longest  in  pure  0  (12  hours) 
(Castell),  and  not  so  long  in  N,  — H  (1  hour)  — COa  (10  minutes),  CO 
(42  minutes)  — CI  (2  minutes),  or  in  a  vacuum  (20  to  30  minutes) 
(Boyle,  1G70;  Fontana,  Tiedemann,  1847),  even  when  there  is  watery 


THE   CARDIAC  NERVES.  97 

vapour  present  to  prevent  evaporation.  If  the  heart  be  re-introduced 
into  0  it  begins  to  beat  again.  [An  excised  heart  suspended  in 
ordinary  air  beats  three  to  four  times  as  long  as  a  heart  which  is 
placed  upon  a  glass-plate.]  A  heart  which  has  ceased  to  contract 
spontaneously  may  contract  when  an  electrical  stimulus  is  applied  to 
it,  but  it  does  not  do  so  for  a  longer  time  than  other  muscles  (Budge). 

56.  Innervation  of  the  Heart. 

[When  the  heart  is  removed  from  the  body,  or  when  all  the  nerves 
which  pass  to  it  are  divided,  it  still  beats  for  some  time,  so  that  its 
movements  must  depend  upon  some  mechanism  situated  within  itself. 
The  ordinary  rhythmical  movements  of  the  heart  are  undoubtedly 
associated  with  the  presence  of  nerve  ganglia,  wdiich  exist  in  the 
substance  of  the  heart — the  intracardiac  ganglia.  But  the  movements 
of  the  heart  are  influenced  by  nervous  impulses  wdiich  reach  it  from 
without,  so  that  there  falls  to  be  studied  an  intracardiac  and  an  extra- 
cardiac  nervous  mechanism.] 

57.  The  Cardiac  Nerves. 

The  cardiac  plexus  is  composed  of  the  following  nerves — (1.)  The 
cardiac  branches  of  the  vagus,  the  branch  of  the  same  name  from  the 
external  branch  of  the  superior  laryngeal,  a  branch  from  the  inferior 
laryngeal,  and  sometimes  branches  from  the  pulmonary  plexus  of  the 
vagus  (more  numerous  on  the  right  side).  (2.)  The  superior,  middle, 
inferior,  and  lowest  cardiac  branches  of  the  three  cervical  ganglia  and 
the  first  thoracic  ganglia  of  the  sympathetic.  (3.)  The  inconstant 
twig  of  the  descending  branch  of  the  hypoglossal  nerve,  which, 
according  to  Luschka,  arises  from  the  upper  cervical  ganglia.  From 
the  plexus  there  proceed — the  deep  and  the  superficial  nerves  (the 
latter  usually  at  the  division  of  the  pulmonary  artery  under  the  arch  of 
the  aorta,  and  containing  a  ganglion).  The  following  nerves  may  be 
separately  traced  from  the  plexus — 

{a.)  The  plexus  coronarius  dexter  and  sinister  (Scarpa),  which  con- 
tains the  vaso-motor  nerves  for  these  vessels  (physiological  proof  still 
w^anting)  as  well  as  the  nerves  (sensory?)  proceeding  from  them  (to 
the  pericardium  1) 

(J.)  Intra-cardiac  Nerves  and  Ganglia. — The  nerves  lying  in  the 
grooves  of  the  heart  and  in  its  substance,  containing  numerous  ganglia 
(Remak),  which  are  regarded  as  the  automcdic  motm'  centres  of  the 
heart.  A  nervous  ring  containing  numerous  ganglia  corresponds  to  the 
margin  of  the  septum  atriorum;  there  is  another  in  the  auriculo- 
ventricular  groove.  Where  the  two  meet,  they  exchange  fibres.  The 
ganglia  usually  lie  near  the  pericardium.     In  mammals  the  two  largest 


98 


MOTOR  CENTRES  OF  THE  HEART. 


ganglia  lie  near  the  orifice  of  the  superior  vena  cava — in  birds  the 
largest  ganglion  (containing  thousands  of  ganglionic  cells)  lies  pos- 
teriorly where  the  longitudinal  and  transverse  sulci  cross  each  other. 
Fine  branches,  also  provided  with  small  ganglia,  proceed  from  these 
ganglia,  and  penetrate  the  muscular  walls  of  the  auricles  and  ventricles. 
Nerves  of  the  Frog's  Heart. — In  the  frog  there  is  a  large  ganglion 
(Bemah's)  near  the  fibres  of  the  vagus  within  the  wall  of  the  sinus 
venosus.  Branches  of  the  vagus  proceed  from  this  ganglion  along  the  an- 
terior and  posterior  walls  of  the  auricular  septum,  and  each  of  these  con- 
tains a  ganglion  in  the  auriculo-ventricular  groove,  these  aggregations 
of  ganglion  cells  constituting  Bidde/s  ganglion.  Fine  branches  proceed 
from  this  ganglion,  but  they  can  be  traced  only  for  a  short  distance,  so 
that  the  greater  part  of  the  ventricle  appears  to  be  devoid  of  nerves. 

According  to  Openchowsky,  eveiy  part  of  the  heart  (frog,  triton,  tortoise)  con- 
tains nerve-fibres  which  are  coanected  with  every  muscular  fibre.  In  the  aui-icles, 
at  the  end  of  the  non-mednllated  fibre,  a  tri-radiate  nucleus  exists  which  gives  ofi' 
fibrils  to  the  muscular  bundles. 

There  is  a  network  of  fine  nerve-fibres  distributed  immediately  under  the  endo- 
cardium—these fibres  act  partly  in  a  centripetal  direction  on  the  cardiac  ganglia, 
and  are  partly  motor  for  the  endocardial  muscles.  The  parietal  layer  of  the  peri- 
cardium contains  (sensory)  nerve-fibres.  The  following  kinds  of  nerve-cells  are  found 
— unipolar  cells,  the  single  processes  of  which  aftervvards  divide ;  Upolar  cells  (Fig. 
3 1  a),  which  in  the  frog  possess  a  straight  [n)  and  usually  also  a  spiral  process  (o). 

58.  The  Automatic  Motor  Centres  of  the  Heart. 

(1.)  We  must  assume  that  the  nervous  centres  which  excite  the 
cardiac  movements,  and  maintain  the  rhythm  of  these  movements,  lie 
within  the  heart,  and  that  they  are  probably 
represented  by  the  ganglia. 

(2.)  There  are — not  one,  but  several,  of  these 
centres  in  the  heart,  which  are  connected  with 
each  other  by  conducting  paths.  As  long  as 
the  heart  is  intact,  aU  its  parts  are  made  to 
move  in  rhythmical  sequence  from  a  principal 
central  point,  an  impulse  being  conducted 
from  this  centre  through  the  conducting  paths 
(Bonders).  What  the  "discharging  forces" 
of  these  regular  progressive  movements  are,  is 
unknown.  If,  however,  the  heart  be  subiected 
to  the  action  of  difiuse  stimuli  {e.g.,  strong 
electrical  currents),  all  the  centres  are  thrown 
into  action,  and  a  spasm-like  action  of  the  heart 
occurs.  The  dominating  centre  lies  in  the 
auricles,  hence  the  regular  progressive  move- 
ment usually  starts  from  them.     If  the  excit- 


Fig.  31a. 
Pyi-iform  ganglionic  bi- 
polar ners-e-cell  fi-om 
the  heart  of  a  frog 
(Arnold) — m,  sheath; 
n,  straight  process ;  o, 
spiral  process. 


MOTOR  CENTRES  OP  THE  HEART.  99 

ability  is  diminished  {e.g.,  by  touching  the  septum  with  opium — 
Ludwig,  Hoffa),  other  centres  seem  to  undertake  this  function,  in 
which  case  the  movement  may  extend  from  the  ventricles  to  the 
auricles.  If  a  heart  be  cut  into  pieces,  so  that  the  individual  pieces 
still  remain  connected  with  each  other,  the  regular  peristaltic  or 
wave-like  movements  proceeding  from  the  auricles  to  the  ventricle, 
may  continue  for  a  long  time  (Bonders,  Engelmann).  If  the  heart, 
however,  be  completely  divided  into  two  distinct  pieces  (auricle  and 
ventricle),  the  movements  of  both  parts  continue,  but  not  in  the  same 
sequence — they  beat  at  different  rates. 

(3.)  All  stimuli  of  moderate  strength  applied  directly  to  the  heart 
cause  at  first  an  increase  of  the  rhythmical  heart-beats ;  stronger 
stimuli  cause  a  diminution,  and  it  may  be  paralysis,  which  is  often 
preceded  by  a  convulsive  movement.  Increased  activity  exhausts 
the  energy  of  the  heart  sooner. 

(4.)  The  auricular  centres  seem  to  be  more  excitable  than  those  of 
the  ventricle;  hence,  in  a  heart  left  to  itself  the  auricles  pulsate 
longest. 

(5.)  The  heart  may  be  excited  (reflexly)  from  its  inner  surface. 
Weak  stimuli  applied  to  the  inner  surface  of  the  heart  greatly 
accelerate  the  heart's  action,  the  stimulus  required  being  much 
feebler  than  that  applied  to  the  external  surface  of  the  heart. 
Strong  stimuli,  which  bring  the  heart  to  rest,  also  act  more  easily  when 
applied  to  the  inner  surface  than  when  they  are  applied  to  its  outer 
surface  (Henry,  1832).  The  ventricle  is  always  the  part  first  to  be 
paralysed. 

(6.)  In  order  that  the  heart  may  continue  to  contract,  it  is  necessary 
that  it  be  supplied  with  a  fluid  which  in  addition  to  0  (Ludwig,  Volk- 
mann,  Goltz)  must  contain  the  necessary  nutritive  materials.  The  most 
perfect  fluid,  of  course,  is  blood.  Hence  the  heart  ceases  to  beat 
in  an  indifferent  fluid  (0"6  p.c.  sodium  chloride),  but  its  activity  may 
be  revived  by  supplying  it  with  a  proper  nutritive  fluid. 

Cardiac  Nutritive  Fluids. — These  nutritive  fluids  are  such  as  contain  serum- 
albvunin — e.g.,  blood,  serum,  or  lymph.  Serum  retains  its  nutritive  properties 
even  after  it  has  been  subjected  to  dififusion  (Martins  and  Kronecker).  Milk  and 
whey  (v,  Ott),  normal  saline  solution  (0"6  per  cent.  NaCl)  mixed  with  blood, 
albumin,  or  peptone,  and  0"3  per  cent,  sodium  carbonate  (Kronecker,  Merunowicz, 
and  Sti^non),  or  a  trace  of  caustic  soda  (Gaule),  or  a  solution  of  the  salts  of 
serum,  are  suitable, 

(7.)  The  independent  pulsations  of  parts  of  the  heart  which  are 
devoid  of  ganglia,  show  that  the  presence  of  ganglia  is  not  absolutely 
necessary  in  order  to  have  rhythmical  pulsation.  Direct  stimulation 
of  the  heart  may  cause  these  movements.  But  the  ganglia  are  more 
excitable  than  the  heart-muscle  itself,  and  they  conduct  the  impulses 


100  STANNIUS'   EXPERIMENT. 

which  lead  to  the  regular  alternatmg  action  of  the  various  parts  of  the 
heart,  so  that  under  normal  circumstances,  we  must  assume  that  the 
action  of  the  heart  is  governed  by  the  ganglia. 

The  chief  experiments  upon  which  the  above  statements  are  based 
consist  of  two  classes: — (1.)  Where  the  heart  is  incised  or  divided; 
and  (2.)  where  it  is  stimulated  directly. 

(I.)  Experiments  by  CUTTING  and  ligaturing  the  heart.  These 
experiments  have  been  made  chiefly  upon  the  frog's  heart.  The 
ligature  experiments  are  performed  by  tightening  and  then  relaxing 
a  ligature  placed  around  the  heart,  so  that  the  physiological  connection 
is  destroyed,  while  the  anatomical  or  mechanical  connections  (con- 
tinuity of  the  cardiac  wall,  intact  condition  of  its  cavities)  still  exist. 
The  most  important  of  these  experiments  are — 

(1.)  Stannius'  Experiment. — If  the  sinus  venosus  of  a  frog's  heart 
be  separated  from  the  auricles,  either  by  an  incision  or  by  a  ligature, 
the  auricles  and  ventricle  stand  still  in  diastole,  whilst  the  veins  and 
the  remainder  of  the  sinus  continue  to  beat.  If  a  second  incision  be 
made  at  the  auriculo-ventricular  groove,  as  a  rule  the  ventricle  begins 
at  once  to  beat  again,  whilst  the  auricles  remain  in  the  condition  of 
diastolic  rest.  According  to  the  position  of  the  second  ligature  or 
incision,  the  auricles  may  also  beat  along  with  the  ventricles,  or  the 
auricles  alone  may  beat,  while  the  ventricles  remain  at  rest  (1852). 

Explanations. — Various  explanations  of  these  experiments  have  been  given  : — 
(a.)  Eemak's  ganglion  in  the  sinus  vinosus  is  distinguished  by  its  great  excitability, 
while  Bidder's  ganglion  in  the  auriculo-ventricular  groove  is  less  excitable  ;  in  the 
normal  condition  of  the  heart  the  motor  impulse  is  carried  from  the  former  to  the 
latter.  If  the  sinus  venosus  be  separated  from  the  heart,  Remak's  ganglion  has  no 
action  on  the  heart.  The  heart  stops  for  two  reasons — first,  because  Bidder's 
ganglion  alone  has  not  sufiicient  energy  to  excite  it  to  action,  and  because 
the  inhibitory  fibres  of  the  vagus  going  to  the  heart  have  been  stimulated  by 
being  divided  at  this  point  (Heidenhain).  [That  stimulation  of  the  inhibitory 
fibres  of  the  vagus  is  not  the  cause  of  the  standstill,  is  proved  by  the  fact  that  the 
standstill  occurs  even  after  the  administration  of  atropine,  which  paralyses  the 
cardiac  inhibitory  mechanism.]  The  passive  heart,  however,  may  be  made  to 
contract  by  mechanically  stimulating  Bidder's  ganglion — e.g.,  by  a  slight  prick 
with  a  needle  in  the  auriculo-ventricular  groove  (H.  Munk),  or  by  the  action  of  a 
constant  current  of  moderate  strength  (Eckhard),  the  ventricular  pulsation  at  the 
same  time  preceding  the  auricular  (v.  Bezold,  Bernstein).  If  the  auriculo- 
ventricular  groove  be  divided,  the  ventricle  pulsates  again,  because  Bidder's  ganglion 
has  been  stimulated  by  the  act  of  dividing  it;  while,  at  the  same  time,  the  ventricle 
is  withdrawn  from  the  inhibitory  influence  of  the  vagus  produced  by  the  first 
division  at  the  sinus  venosus.  If  the  line  of  separation  is  so  made  that  Bidder's 
ganglion  remains  attached  to  the  auricles,  these  pulsate,  and  the  ventricle,  rests ; 
if  it  be  divided  into  halves,  the  auricles  and  ventricles  pulsate,  each  half  being 
excited  by  the  portion  of  the  ganglion  in  relation  with  it.  (6.)  According  to 
another  view,  both  Remak's  (a.)  and  Bidder's  ganglia  {&.)  are  motor  centres,  but 
in  the  auricles  there  is  in  addition  an  inhibitory  ganglionic  system  (c.)  (Bezold, 
Traube).     Under  normal  circumstances  a  -t-  &  is  stronger  than  c,  while  c  is  stronger 


LIGATURE   AND   SECTION   OF  THE   HEART.  101 

than  a  or  6  separately.  If  the  sinus  venosus  be  separated  it  beats  in  virtue  of  a; 
on  the  other  hand,  the  heart  rests  because  c  is  stronger  than  h.  If  the  section  be 
made  at  the  level  of  the  auriculo-ventricular,  the  auricles  stand  still  owing  to  c, 
while  the  ventricle  beats  owing  to  h. 

(2.)  If  the  ventricle  of  a  frog's  heart  be  separated  from  the  rest  of 
the  heart  by  means  of  a  ligature,  or  by  an  incision  carried  through 
it  at  the  level  of  the  auriculo-ventricular  groove,  the  sinus  and  atria 
pulsate  undisturbed  as  before  (Descartes,  1644),  but  the  ventricle  stands 
still  in  diastole.  Local  stimulation  of  the  ventricle  causes  a  single 
contraction.  If  the  incision  be  so  made  that  the  lower  margin  of  the 
auricular  septum  remains  attached  to  the  ventricle,  the  latter  pulsates 
(Rosenberger,  1850). 

(3.)  Section  of  the  Heart. — Engelmann's  recent  experiments  show 
that  if  the  ventricle  of  a  frog's  heart  be  cut  up  into  two  or  more  strips 
in  a  zig-zag  way,  so  that  the  individual  parts  still  remain  connected 
with  each  other  by  muscular  tissue,  the  strips  still  beat  in  a  regularly 
progressive,  rhythmical  manner,  provided  one  strip  is  caused  to  con- 
tract. The  rapidity  of  the  transmission  is  about  10  to  30  mm.  per  sec. 
(Engelmann).  Hence,  it  appears  that  the  conducting  paths  for  the 
imjjulse  causing  the  contraction  are  not  nervous,  but  must  be  the 
contractile  mass  itself.  It  has  not  been  proved  that  nerve-fibres 
proceed  from  the  ganglia  to  all  the  muscles. 

[According  to  Marchand's  experiments,  it  takes  a  very  long  time  for  the  excite- 
ment to  pass  from  the  auricles  to  the  ventricle — a  much  longer  time,  in  fact,  than 
it  would  require  to  conduct  the  excitement  through  muscle — so  that  it  is  probable 
that  the  propagation  of  the  impulse  from  the  auricles  to  the  ventricle  is  conducted 
by  nervous  channels  to  the  auriculo-ventricular  nervous  apparatus.  In  fact,  in  the 
mammalian  heart  the  muscular  fibres  of  the  auricles  are  quite  distinct  from  those 
of  the  ventricle.] 

(4.)  It  is  usually  stated  that  when  the  apex  of  a  frog's  heart  is  severed 
from  the  rest  of  the  heart,  it  no  longer  pulsates  (Heidenhain,  Goltz),  but 
such  an  apex,  if  vstimulated  mechanically,  responds  with  a  single  con- 
traction. 

Action  of  Fluids  on  the  Heart — Haller  was  of  opinion,  that 
the  venous  blood  was  the  natural  stimulus  which  caused  the 
heart  to  contract.  That  this  is  not  so,  is  proved  at  once  by  the  fact 
that  the  heart  beats  rhythmically  when  it  contains  no  blood. 

Blood  and  other  fluids  which  are  supplied  to  an  excised  heart  are 
not  the  cause  of  its  rhythmical  movements,  but  only  the  conditions  on 
which  these  movements  depend.  Thus,  a  heart  which  is  too  feeble  to 
contract  may  be  made  to  do  so  by  sujiplying  it  with  a  fluid  containing 
proteids,  when  a  latent  intra-cardiac  mechanism  is  brought  into  action, 
the  albuminous  or  other  fluid  merely  supplying  the  pabulum  for  the 
excitable  elements. 


102 


ACTION   OF  FLUIDS   ON   THE  HEART. 


[Methods. — The  action  of  fluids  upon  the  excised  frog's  heart  has  been  rendered 
possible  by  the  invention  of  the  "frog-manometer"  of  Ludwig.  The  apparatus 
has  been  improved  by  Ludwig's  pupils,  and  already  numerous  important  results 
have  been  obtained.  The  apparatus,  Fig,  32  consists  of — (1.)  a  double-way 
cannula,  c,  which  is  tied  into  the  heart,  h;  (2.)  a  manometer,  m,  connected  with  c, 
and  registering  the  movements  of  its  mercury  on  a  revolving  cylinder,  cyl ;  (3. ) 
two  Mariotte's  flasks,  a  and  6,  which  are  connected  with  the  other  limb  of  the 
cannula.  Either  «  or  6  can  be  placed  in  communication  with  the  interior  of  the 
heart  by  means  of  the  stop-cock,  s.  The  fluid  in  one  graduated  tube  may  be 
poisoned,  and  the  other  not;  c?  is  a  glass  vessel  for  fluid,  in  which  the  heart 
pulsates,  e  and  e'  are  electrodes,  e  is  inserted  into  the  fluid  in  d,  e'  is  attached  to 
the  german  silver  cannula  which  is  shown  in  Fig.  32a. 


Fig.  32. 
Scheme  of  a  frog-manometer— a,  b, 
Mariotte's  flasks  for  the  nutrient 
fluids  ;  s,  stop-cock  ;  c,  cannula  ; 
m,  manometer ;  A,  heart ;  d,  glass 
cup  for  h;  e,  e',  electrodes;  cyl, 
revolving  cylinder. 


Fig.  32a. 

Double-way  or  perfu- 
sion cannula  (nat. 
size)  for  a  frog's 
heart — c,  for  fixing 
an  electrode ;  d,  the 
heart  is  tied  over  the 
flanges,  preventing 
it  from  slipping  out ; 
e,  section  of  d. 


In  the  tonometer  of  Roy  (Fig.  33)  the  ventricle,  h,  or  the  whole  heart,  is  placed 
in  an  air-tight  chamber;  o,  filled  with  oil,  or  with  oil  and  normal  saline  solution. 
As  before,  a  "  perfusion  "  cannvila  is  tied  into  the  heart.  A  piston,  p,  works  up 
and  down  in  a  cylinder,  and  is  adjusted  by  means  of  a  thin  flexible  animal  mem- 
brane, such  as  is  used  by  perfumers.  Attached  to  the  piston  by  means  of  a  thread 
is  a  writing  lever,  I,  which  records  the  variations  of  pressure  within  the 
chamber,  o.  When  the  ventricle  contracts,  it  becomes  smaller,  diminishes 
the  pressure  within  o,  and  hence  the  piston  and  lever  rise ;  conversely,  when 
the  heart  dilates,  the  lever  and  piston  descend.  Variations  in  the  volume  of 
the  ventricle  may  be  registered,  without  in  any  way  interfering  with  the  flow 
of  fluids  through  it. 

Two  preparations  of  the  frog's  heart  have  been  used— (1.)  The  ^' heart"  in  which 
case  the  cannula  is  introduced  into  the  heart  through  the  sinus  venosus,  and  a 


ACTION   OF  FLUIDS   ON   THE   HEART. 


103 


ligature  is  tied  over  it  around  the  auricle,  or  it  may  be  the  sinus  venosus.  Thus 
the  auriculo-ventricular  ganglia  and  other  nervous  structures  remain  in  the  pre- 
paration. This  was  the  heart  preparation  employed  by  Luciani  and  Rossbach. 
(2.)  In  the  ^^ heart-apex"  preparation  the  cannula  is  introduced  as  before,  but  the 
ligature  is  |^tied  on   it  on  the  ventricle,  several  millimetres  heloio  the  auriculo- 


Fig.  33. 

Roy's  apparatus  or  tonometer  for  the  heart— ^,  heart;  o,  air-tight  chamber; 
p,  piston;  I,  writing  lever. 

ventricular  groove,  so  that  this  preparation  contains  none  of  the  auriculo-ventricu- 
lar ganglia,  and,  according  to  the  usual  statement,  this  part  of  the  heart  is  devoid 
of  nerve  ganglia.  This  is  the  preparation  which  was  used  by  Bowditch,  Kronecker 
and  Stirling,  Merunomcz,  and  others.  The  first  effect  of  the  application  of  the 
ligature  in  both  cases  is,  that  both  preparations  cease  to  beat,  but  the  "heart" 
usually  resumes  its  rhythmical  contractions  within  several  minutes,  while  the 
"heart-apex"  does  not  contract  spontaneously  until  after  a  much  longer  time 
(lOtoOOmins.). 

If  the  "Heart- Apex"  be  filled  with  a  0*6  per  cent,  solution  of  common  salt, 
the  contractions  are  at  first  of  greater  extent,  but  they  afterwards  cease,  and 
the  preparation  passes  into  a  condition  of  "apparent  death;"  while  if  the  action 
of  the  fluid  be  prolonged,  the  heart  may  not  contract  at  all,  even  when  it  is 
stimulated  electrically  or  mechanically.  It  may  be  made,  however,  to  pulsate 
again,  if  it  be  supplied  with  saline  solution  containing  blood  (I  to  10  per 
cent).  The  "stille"  or  state  of  quiescence  may  last  90  mins.  (Kronecker  and 
Merunowicz).  If  the  ventricle  be  nipped  with  wire  forceps  at  the  junction  of  the 
upper  with  its  middle  third,  so  as  to  separate  the  lower  two-thirds  of  the  ventrical 
physiologically  but  not  anatomically  from  the  rest  of  the  heart,  then  the  apex  will 
cease  to  contract,  although  it  is  still  supplied  with  the  frog's  own  blood  (Bernstein, 
Bowditch).  The  physiologically  isolated  apex  may  be  made  to  beat  by  clamping 
the  aortic  branches  to  prevent  blood  passing  out  of  the  heart,  and  thus  raising  the 
intracardial  pressure.  The  rate  of  the  beat  of  the  apex  is  independent  of  and 
slower  than  that  of  the  rest  of  the  heart.  This  experiment  proves  that  the 
amount  of  pressure  within  the  apex  cavity  is  an  important  factor  in  the 
causation  of  the  spontaneous  apex  beats  (Gaskell).  If  blood-serum,  to  which 
a  trace  of  delphinin  is  added,  be  transfused  or  "perfused"  through  the  heart, 
it  begins  to  beat  within  a  minute,  continues  to  beat  for  several  seconds,  and 
then  stands  still  in  diastole  (Bowditch).      Quinine  (Schtschepotjew)  and  a  mixture 


104 


ACTION    OF   FLUIDS   ON    THE   HEART. 


of  atropine  and  muscarin  have  a  similar  action  (v.  Basch).  These  experiments 
shew  that,  provided  no  nervous  apparatus  exists  loithin  the  heart-apex,  the  cause  of 
the  varying  contraction  is  to  be  sought  for  in  the  musculature  of  the  heart 
(Kronecker),  and  that  the  stimulus  necessary  for  the  systole  of  the  heart's- 
apex  may  arise  within  itself  (Aubert).  If  there  is  no  nervous  apparatus  of  any 
kind  present,  then  we  must  assume  that  the  heart-muscle  may  execute  rhythmical 
movements  independently  of  the  presence  of  any  nervous  mechanism,  although  it 
is  usually  assumed  that  the  ganglia  excite  the  heart-muscle  to  pulsate  rhythmically. 
It  is  by  no  means  definitely  proved  that  the  heart-apex  is  devoid  of  all  nervous 
structures,  which  may  act  as  originators  of  these  rhythmical  impulses. 

The  "Heart"  preparation  in  many  respects  behaves  like  the  foregoing,  i.e., 
it  is  exhausted  after  a  time  by  the  continued  application  of  normal  saline 
solution  (0"6  per  cent.  NaCl),  while  its  activity  may  be  restored  by  supplying  it 
with  albuminous  and  other  fluids  (p.  99).] 

[(5.)  Luciani  found  that  such  a  heart,  when  filled  with  pure  serum, 
produced  groups  of  pulsations  with  a  long  diastolic  pause  between  every 
two  groups  (Fig.  34).  The  successive  beats  in  each  group  assume  a 
"staircase"  character  (p.  107).     These  periodic  groups  undergo  many- 


Fig.  31. 
Four  groups  of  pulsations  with  intervening  pauses,  as  obtained  by  Luciani,  with 
their  "staircase"  character.     The  points  on  the  abscissa  were  marked  every 
ten  seconds. 

changes ;  they  occur  when  the  heart  is  filled  with  pure  serum  free 
from  blood-corpuscles,  and  they  disappear  and  give  place  to  regular 
pulsations  when  defibrinated  blood  or  serum  containing  hemoglobin 
or  normal  saline  solution  (Eossbach)  is  used.  They  also  occur  when 
the  blood  within  the  heart  has  become  dark-coloured — i.e.,  when  it 
has  been  deprived  of  certain  of  its  constituents — and  if  a  trace  of 
veratrin  be  added  to  bright-red  blood  they  occur.] 

(6.)  The  same  apparatus  permits  of  the  application  of  electrical  stimuli 
to  either  of  the  above-named  preparations.  An  apex-preparation,  when 
stimulated  with  even  a  weak  induction  shock,  always  gives  its  maximal 
contraction,  and  when  a  tetanising  current  is  applied  tetanus  does  not 
occur  (Kronecker  and  Stirling).  When  the  opening  and  closing 
shocks  of  a  sufficiently  strong  constant  current  are  applied  to  the 
heart-apex,  it  contracts  with  each  closing  or  opening  shock.  [When 
a  constant  current  is  applied  to  the  lower  two-thirds  of  the  ventricle 
(heart-apex),  under  certain  conditions  the  apex  contracts  rhythmically. 


ACTION   OF  HEAT   ON   THE  HEART. 


105 


This  is  an  important  fact  in  connection  with  any  theory  of  the  cardiac 
beat.] 

(7.)  If  the  bulbus  aortse  (frog)  be  ligatured,  it  still  pulsates,  provided 
the  internal  pressure  be  moderate.  Should  it  cease  to  beat,  a  single 
stimulus  makes  it  respond  by  a  series  of  contractions.  Increase  of 
temperature  to  35°C.,  and  increase  of  the  pressure  within  it  increase 
the  number  of  pulsations  (Engelmann). 

(II.)  Direct  Stimulation  of  the  Heart. — All  direct  cardiac  stimuli  act 
more  energetically  on  the  inner  than  on  the  outer  surface  of  the  heart. 
If  strong  stimuli  are  applied  for  too  long  a  time,  the  ventricle  is  the 
part  first  paralysed. 

(a.)  Thermal  Stimuli. — [Heat  affects  the  number  or  frequency  and  the 
amplitude  of  the  pulsations,  as  well  as  the  duration  of  the  systole  and  diastole  and 
the  excitcOnUt ij  of  the  heart.]  Descartes  (1614)  observed  that  heat  increased  the 
number  of  pulsations  of  an  eel's  heart.  A.  v.  Humboldt  found  that  when  a  frog's 
heart  was  placed  in  lukewarm  water,  the  number  of  beats  increased  from  12  to  40 
per  minute.  As  the  temperature  increases,  the  number  of  beats  is  at  first  con- 
siderably increased,  but  afterwards  the  beats  again  become  fewer,  and  if  the 
temperature  is  raised  above  a  certain  limit  the  heart  stands  still,  the  myosin  of 
which  its  fibres  consist  is  coagulated,  and  "heat-rigor"  occurs.  Even  before 
this  stage  is  reached,  however,  the  heart  may  stand  still,  the  muscular  fibres 


Fig.  35. 
Fig.  a,  Contractions  of  a  frog's  heart  at  19°C.;  h,  at  34°C.;  c,  at  3°C. 


106  ACTION   OF  MECHANICAL  AND   ELECTRICAL   STIMULL 

appearing  to  remain  contracted.  The  ventricles  usually  cease  to  beat  before  the 
auricles  (Schelske),  The  size  and  extent  of  the  contractions  increase  up  to  about 
20°C.,  but  above  this  point  they  diminish  (Fig.  35).  The  time  occupied  by  any 
single  contraction  at  20°O.  is  only  about  -^  of  the  time  occupied  by  a  contraction 
occurring  at  5°C.  ' 

A  heart  which  has  been  warmed  is  capable  of  reacting  pretty  rapidly  to  inter- 
mittent stimuli,  while  a  heart  at  a  low  temperature  reacts  only  to  stimuli  occurring 
at  a  considerable  interval.  If  a  frog  be  kept  in  a  cold  place  its  heart  beats  slowly 
and  does  little  work,  but  if  the  heart  be  supplied  with  the  extract  of  a  frog  which 
has  been  kept  warm,  it  is  rendered  more  capable  of  doing  work  (Gaule). 

Cold. — When  the  temperature  of  the  blood  is  diminished,  the  heart  beats  slower 
(Kielmeyer,  1793).  A  frog's  heart,  placed  between  two  watch-glasses  and  laid  on 
ice,  beats  very  much  slower  (Ludwig,  1861).  The  pulsations  of  a  frog's  heart  stop 
when  the  heart  is  exposed  to  a  temperature  of  4°C.  to  0°  (E.  Cyon).  If  a  frog's 
heart  be  taken  out  of  warm  water,  and  suddenly  placed  upon  ice,  it  beats  more 
rapidly,  and  conversely,  if  it  be  taken  from  ice  and  placed  in  warm  water,  it  beats 
more  slowly  at  first  and  more  rapidly  afterwards  (Aristow). 

[Methods. — The  effect  of  heat  on  a  heart  may  be  studied  by  the  aid  of  the  frog- 
manometer,  the  fluid  in  which  the  heart  is  placed  being  raised  to  any  temperature 
required.  For  demonstration  purposes,  the  heart  of  a  pithed  frog  is  excised  and 
placed  on  a  glass  slide  under  a  light  lever,  such  as  a  straw.  The  slide  is  warmed 
by  means  of  a  spirit-lamp.  In  this  way  the  frequency  and  amplitude  of  the  con- 
tractions are  readUy  made  visible  at  a  distance.] 

[Gaskell  fixes  the  heart  by  means  of  a  clamp  placed  round  the  auriculo-ven- 
tricular  groove,  while  levers  are  placed  horizontally  above  and  below  the  heart. 
These  levers  are  fixed  to  part  of  the  auricles  and  to  the  apex  by  means  of  threads. 
Each  part  of  the  heart  attached  to  a  lever,  as  it  contracts,  pulls  upon  its  own 
lever,  so  that  the  extent  and  duration  of  each  contraction  may  be  registered.  This 
method  is  applicable  for  studying  the  effect  of  the  vagus  and  other  nerves  upon  the 
heart  (Roy).] 

(6.)  Mechanical  Stimuli. — Pressure  applied  externally  to  the  heart  accelerates 
its  action.  In  the  case  of  Frau  Serafin,  v.  Ziemssen  found,  that  slight  pressure  on 
the  auriculo-ventricular  groove  caused  a  second  short  contraction  of  both  ventricles 
after  the  heart-beat.  Strong  pressure  causes  a  very  irregular  action  of  the  cardiac 
muscle.  This  may  readily  be  produced  by  compressing  the  freshly  excised  heart 
of  a  dog  between  the  fingers. 

The  intra-cardiac  pressure  also  affects  the  heart-beat.  If  the  pressure  within  the 
heart  be  increased,  the  heart-beats  are  gradually  increased,  if  it  be  diminished  the 
number  of  beats  diminishes  (Ludwig  and  Thiry).  If  the  intra-cardiac  pressure  be 
very  greatly  increased,  the  heart's  action  becomes  very  irregular  and  slower 
(Heidenhain).  A  heart  which  has  ceased  to  beat  may,  under  certain  circum- 
stances, be  caused  to  execute  a  single  contraction  if  it  be  stimulated  mechanically, 
(c.)  Electrical  Stimuli.— A  constant  electrical  current  of  moderate  strength 
increases  the  number  of  heart-beats,  v.  Ziemssen  found  in  the  case  of  Frau 
Serafin  (p.  74,  3),  that  the  number  of  beats  was  doubled,  when  a  constant  uninter- 
rupted strong  current  was  passed  through  the  ventricles.  If  the  constant  current 
be  very  strong,  or  if  tetanising  induction  currents  be  used,  the  cardiac  muscle 
assumes  a  condition  resembling,  but  not  identical  with,  tetanus  (Ludwig  and 
Hoffa),  and  of  course  this  results  in  a  fall  of  the  blood-pressure  (Sigm.  Mayer). 

When  a  single  induction  shock  is  applied  to  the  ventricle  of  a  frog's  heart  during 
systole,  it  has  no  apparent  effect ;  but  if  it  is  applied  during  diastole,  the  succeeding 
contraction  takes  place  sooner.  The  auricles  behave  in  a  similar  manner.  Whilst 
they  are  contracted,  an  induction  shock  has  no  effect ;  if,  however,  the  stimulus  is 
applied  during  diastole,  it  causes  a  contraction,  which  is  followed  by  systole  of  the 


ACTION   OF  ELECTRICAL   STIMULI    ON   THE   HEART.  107 

ventricle  (Hildebrand).  Even  when  strong  tetanising  induction-shocks  are  applied 
to  the  heart,  they  do  not  produce  tetanus  of  the  entire  cardiac  musculature,  or  as  it 
is  said,  "the  heart  knows  no  tetanus"  (Kronecker  and  Stirling).  Small  white  local 
weal-like  elevations— such  as  occur  when  the  intestinal  musculature  is  stimulated 
— appear  between  the  electrodes.  They  may  last  several  minutes.  A  frog's  heart, 
which  yields  weak  and  irregular  contractions,  may  be  made  to  execute  regular 
rhythmical  contractions  isochronous  with  the  stimuli,  if  electrical  stimuli  are  used 
(Bowditch).  In  this  case  the  weakest  stimuli  (which  are  still  active)  behave  like 
the  stronger  stimuli — even  with  the  weak  stimulus  the  heart  always  gives  the 
strongest  contraction  possible.  Hence  this  minimal  electrical  stimulus  is  as 
effective  as  a  "maximal"  stimulus  (Kronecker  and  Stirling). 

V.  Ziemssen  found  that  he  could  not  alter  the  heart-beats  of  the  human  heart  (Frau 
Serafin,  p.74,3),  even  with  strong  induction  currents.  The  ventricular  diastole  seemed 
to  be  less  complete,  and  there  were  irregularities  in  its  contraction.  By  opening  and 
closing,  or  by  reversing  a  strong  constant  current  applied  to  the  heart,  the  number 
of  beats  was  increased,  and  the  increase  corresponded  with  the  number  of  electrical 
stimuli;  thus,  when  the  electrical  stimuli  were  120,  140,  180,  the  number  of  heart- 
beats was  the  same,  the  pulse  beforehand  being  SO.  When  180  shocks  per  minute 
were  applied  the  action  of  the  heart  assumed  the  characters  of  the  pulsus  alternans 
(p.  143).  Minimal  stimuli  were  also  found  to  act  like  maximal  stimuli.  The 
normal  pulse-rate  of  80  was  reduced  to  60  and  50,  when  the  number  of  shocks  was 
reduced  in  the  same  ratio.  The  rhythm  became  at  the  same  time  somewhat 
irregular.  In  these  experiments  a  strong  current  is  required,  and  v.  Basch  found 
that  the  same  was  true  for  the  frog's  heart.  Even  in  healthy  persons,  v.  Ziemssen 
ascertained  that  the  energy  and  rhythm  of  the  heart  could  be  modified  by  passing 
an  electrical  current  through  the  uninjured  chest-wall. 

[Method- — The  apparatus  (Fig.  32.)  is  also  well  adapted  for  studying  the  eifect 
of  electrical  currents  upon  the  heart.  Bowditch,  Kronecker  and  Stirling,  and 
other  observers,  used  the  "heart-apex,"  as  it  does  not  contract  spontaneously 
for  some  time  after  the  ligature  is  applied.  One  electrode  is  attached  to  the 
cannula,  and  the  other  is  placed  in  the  fluid  in  which  the  heart  is  bathed.] 

[Opening  induction  shocks,  if  of  sufficient  strength,  caiise  the  heart  to  con- 
tract, while  weak  stimuli  have  no  eifect;  on  the  other  hand,  moderate  stimuli, 
when  they  do  cause  the  heart  to  contract,  always  cause  a  maximal  contrac- 
tion, so  that  a  minimal  stimulus  acts  at  the  same  time  like  a  maximal  stimulus. 
The  heart  either  contracts  or  it  does  not  contract,  and  when  it  contracts  the 
result  is  always  a  "  maximal "  contraction.  Bowditch  found,  that  the  excit- 
ability of  the  heart  was  increased  by  its  own  movements,  so  that  after  a  heart 
had  once  contracted,  the  strength  of  the  stimulus  required  to  excite  the  next 
contraction  may  be  greatly  diminished,  and  yet  the  stimulus  be  effectual.  Usually 
the  amplitude  of  the  first  beat  so  produced  is  not  so  great  as  the  second  beat,  and 
the  second  is  less  than  the  third,  so  that  a  "  staircase "  ("  Treppe  ")  of  beats 
of  successively  greater  extent  are  produced  (Fig.  34. )  This  staircase  arrangement 
occurs  even  when  the  strength  of  the  stimulus  is  kept  constant,  so  that  the  produc- 
tion of  one  contraction  facilitates  the  occurrence  of  the  succeeding  one.  A  staircase 
arrangement  of  the  pulsations  is  also  seen  in  Luciani's  groups  (p.  104).  The  ques- 
tion, whether  a  stimulus  will  cause  a  contraction,  depends  upon  what 
particular  phase  the  heart  is  in,  when  the  shock  is  applied.  Even  comparatively 
weak  stimuli  will  cause  a  heart  to  contract,  provided  the  stimuli  are  applied  at 
the  proper  moment  and  in  the  proper  tempo — i.e.  to  say,  they  become  what 
are  called  "infallible."  If  stimuli  are  applied  to  the  heart,  at  intervals  which 
are  longer  than  the  time  the  heart  takes  to  execute  its  contraction,  they  are 
effectual  or  "adequate,"  but  if  they  are  applied  before  the  period  of  pulsation 
comes  to  an  end,  then  they  are  ineflfectual  (Kronecker).     It  is  quite  clear,  there- 


108    ACTION   OF   CHEMICAL  STIMULI   AND  GASES   ON   THE  HEART. 

fore,  that  the  relation  of  the  strength  of  the  stimulus,  to  the  extent  of  the  contrac- 
tion of  the  cardiac  muscle,  is  quite  different  from  what  occurs  in  a  muscle  of  the 
skeleton,  where  within  certain  limits  the  amplitude  of  the  contraction  bears  a 
relation  to  the  stimulus,  while  in  the  heart  the  contraction  is  always  maximal.] 

{d.)  Chemical  Stimuli. — Many  chemical  substances,  when  applied  in  a  dilute 
solution,  to  the  inner  surface  of  the  heart,  increase  the  heart-beats,  while  if 
they  are  concentrated  or  allowed  to  act  too  long,  they  diminish  the  heart-beats, 
and  paralyse  it.  Bile  (Budge),  bile  salts  (Rbhrig)  diminish  the  heart-beats  (also 
when  they  are  absorbed  into  the  blood  as  in  jaundice)  ;  in  very  dilute  solutions 
both  increase  the  heart-beats  (Landois).  A  similar  result  is  produced  by  acetic, 
tartaric,  citric  (Bobrik),  and  phosphoric  acids  (Ley den).  Chloroform  and  ether, 
applied  to  the  inner  surface,  rapidly  diminish  the  heart-beats,  and  then  paralyse  it; 
but  very  small  quantities  of  ether  (1  per  cent.)  accelerate  the  heart-beat  of  the  frog 
(Kronecker  and  M'Gregor-Robertson),  while  a  solution  of  IJ  to  2  per  cent,  passed 
through  the  heart  arrests  it  temporarily  or  completely.  A  dilute  solution  of 
opium,  strychnia,  or  alcohol  applied  to  the  endocardium,  increases  the  heart-beats 
(C.  Ludwig) ;  if  concentrated  they  rapidly  arrest  its  action.  Chloral-hydrate 
paralyses  the  heart  (P.  v.  Rokitansky). 

Action  of  Gases.-— When  blood  containing  different  gases  was  passed  through 
a  frog's  heart,  Klug  found  that  blood  containing  sulphurous  acid  rapidly  and 
completely  killed  the  heart ;  chlorine  stimulated  the  heart  at  first,  and  ultimately 
killed  it ;  and  laughing-gas  rapidly  killed  it  also.  Blood  containing  sulphuretted 
hydrogen  paralysed  the  heart  without  stimulating  it.  Carbonic  oxide  also 
paralysed  it,  but  if  fresh  blood  was  transfused,  the  heart  recovered.  [Blood  con- 
taining 0  excites  the  heart  (Castell),  while  the  presence  of  much  CO2  paralyses  it, 
and  the  presence  of  CO2  is  more  injurious  than  the  want  of  0.  H  and  N  have  no 
effect.] 

Rossbach  found  on  stimulating  the  ventricle  of  a  frog's  heart  at  a  circumscribed 
area,  either  mechanically,  chemically,  or  electrically,  during  systole,  that  the 
part  so  stimulated  relaxes  in  partial  diastole.  The  immediate  direct  after-effect 
of  this  stimulation  is,  that  the  muscular  fibres  in  the  part  irritated  remain  some- 
what shrivelled.  This  part  ceases  to  act,  and  has  lost  its  vital  functions.  If  the 
stimulus  is  applied  during  diastole,  the  part  irritated  always  relaxes  sooner,  and 
its  diastole  lasts  longer  than  does  that  of  the  parts  which  were  not  stimulated. 
If  weak  stimuli  are  allowed  to  act  for  a  long  time  upon  any  part  of  the  ventricle 
of  a  frog's  heart,  the  part  so  stimulated  always  relaxes  sooner  than  the  non-stimu- 
lated parts,  and  its  diastole  is  also  prolonged. 

Cardiac  Poisons  are  those  substances  whose  action  is  characterised  by  special 
effects  upon  the  movements  of  the  heart.  Amongst  these  are  the  neutral  salts  of 
■potash.  [Until  1863  it  was  believed  that  these  salts  were  just  as  slightly  active  on 
the  heart  as  the  soda  salts,  but  Bernard  and  Grandeau  showed  that  very  small 
doses  of  these  salts  produced  death,  the  heart  standing  still  in  diastole.  An 
excised  frog's  heart  ceases  to  beat  after  one-half  to  one  minute  when  it  is  placed  in 
a  2  per  cent,  solution  of  potassic  chloride.]  Even  a  very  dilute  solution  of  yellow 
prussiate  of  potash  injected  into  the  heart  of  a  frog  causes  the  ventricle  to  stand 
still  in  systole. 

As  early  as  1691,  Clayton  and  Moulin  showed  the  poisonous  action  of  potassium 
sulphate,  and  alum,  as  compared  with  the  non -poisonous  action  of  sodium  chloride, 
which  was  demonstrated  by  Courten  in  1679.  Antiar  (Java  arrow-poison)  causes 
the  ventricle  to  stand  still  in  systole  and  the  auricles  in  diastole.  Some  heart- 
poisons  in  small  doses,  diminish  the  heart's  action,  and  in  large  doses  not  unfre- 
quently  accelerate  it — e.g.,  digitalis,  morphia,  nicotin.  Others,  when  given  in 
small  doses,  accelerate  its  action,  and  in  large  doses  slow  it — veratria,  aconitin, 
camphor. 


NATURE   OF   A   CARDIAC  CONTRACTION.  109 

Special  Actions  of  Cardiac  Poisons.— The  complicated  actions  of  various 

poisons  upon  the  heart,  have  led  observers  to  suppose  that  there  are  various  intra- 
cardiac mechanisms  on  which  these  substances  may  act.  Besides  the  muscular 
fibres  of  the  heart  and  its  automatic  ganglia,  some  toxicologists  assume  that  there 
are  inhibitory  ganglia  into  which  the  inhibitory  fibres  of  the  vagus  pass,  and 
accelerator  ganglia,  which  are  connected  with  the  accelerating  nerve-fibres  of  the 
heart.  Both  the  iiihibitory  and  accelerator  ganglia  are  connected  with  the  automatic 
ganglia  by  conducting  channels. 

Muscarin  stimulates  permanently  the  inhibitory  ganglia,  so  that  the  heart 
stands  still  (Schmiedeberg  and  Koppe).  As  atropin  and  daturin  paralyse  these 
ganglia,  the  stand-still  of  the  heart  brought  about  by  muscarin  may  be  set  aside  by 
atropin.  [If  a  frog's  heart  be  excised  and  placed  in  a  watch-glass,  and  a  few  drops 
of  a  very  dilute  solution  of  muscarin  be  placed  on  it  with  a  pipette,  it  ceases  to 
beat  within  a  few  minutes,  and  will  not  beat  again.  If,  however,  the  muscarin  be 
removed,  and  a  solution  of  atropine  appUed  to  the  heart,  it  will  resume  its  contrac- 
tions after  a  short  time.]  Physostigmin  [Calabar  bean]  excites  the  energy  of  the 
cardiac  muscle  to  such  an  extent,  that  stimulation  of  the  vagus  no  longer  causes 
the  heart  to  stand  still.  lodine-aldehyd,  chloroform,  and  chloral-hydrate  paralyse 
the  automatic  ganglia.  The  heart  stands  still,  and  it  cannot  be  made  to  contract 
again  by  atropine.  The  cardiac  muscle  itself  remains  excitable  after  the  action  of 
muscarin  and  iodine -aldehyd,  so  that  if  it  be  stimulated  it  contracts.  [According 
to  Gaskell,  antiarin  and  digitalin  solutions  produce  an  alteration  in  the  condition 
of  the  muscular  tissue  of  the  apex  of  the  heart  of  the  same  nature  as  that  pro- 
duced by  the  action  of  very  dilute  alkali  solution,  while  the  action  of  a  blood  solution 
containing  muscarin  closely  resembles  that  of  a  dilute  acid  solution  {§  65).] 

[Nature  of  a  Cardiac  Contraction. — The  question  as  to  wliether 
this  is  a  simple  contraction  or  a  compound  tetanic  contraction,  has  been 
much  discussed.  This  mucli  is  certain,  that  the  systolic  contraction 
of  the  heart  is  of  very  much  longer  dui-ation  (8  to  10  times)  than  the 
contraction  of  a  skeletal  muscle  produced  by  stimulation  of  its  motor 
nerve.  When  the  sciatic  nerve  of  a  nerve-muscle  preparation  ("  rheo- 
scopic  limb")  is  adjusted  upon  a  contracting  heart,  a  simple  secondary 
twitch  of  the  limb,  and  not  a  tetanic  spasm,  is  produced  when  the 
heart  (auricle  or  ventricle)  contracts.  This  of  itself  is  not  sufficient 
proof  that  the  systole  is  a  simple  spasm,  for  tetanus  of  a  muscle  does 
not  in  all  cases  give  rise  to  secondary  tetanus  in  the  leg  of  a  rheoscopic 
limb.  Thus,  a  simple  "  initial "  contraction  occurs,  when  the  nerve  is 
applied  to  a  muscle  tetanised  by  the  action  of  strychnia,  and  the  con- 
tracted diaphragm  gives  a  similar  result.  The  question  as  to  whether 
the  heart  can  be  tetanised,  has  been  answered  in  the  negative,  and  as 
yet  it  has  not  been  shown  that  the  heart  can  be  tetanised  in  the  same 
way  that  a  skeletal  muscle  is  tetanised.] 

The  peripheral  or  extra-cardiac  nerves  will  be  discussed  in  connec- 
tion with  the  I^ervous  System. 

59.  The  Cardio-Pneumatic  Movement. 

As  the  heart  within  the  thorax  occupies  a  smaller  space  during  the 
systole  than  during  the  diastole,  it  follows  that  when  the  glottis  is  open, 


no 


THE   CARDIO-PNEUMATIC  MOVEMENT. 


air  must  be  drawn  into  the  chest  when  the  heart  contracts ;  whenever 
the  heart  relaxes,  i.e.,  during  diastole,  air  must  be  expelled  through  the 
open  glottis.  But  we  must  also  take  into  account  the  degree  to  which 
the  larger  intrathoracic  vessels  are  filled  with  blood.  These  movements 
of  the  air  within  the  lungs,  although  slight,  seem  to  be  of  importance 
in  hybernating  animals.  In  animals  in  this  condition,  the  agitation  of 
the  gases  in  the  lungs  favours  the  exchange  of  COg  and  0  in  the  lungs, 
and  this  slow  current  of  air  is  sufl&cient  to  aerate  the  blood  passing 
through  the  lungs.  [Ceradini  called  the  diminution  of  the  volume  of 
the  entire  heart  which  occurs  during  systole  meiocardie,  and  the 
subsequent  increase  of  volume  when  the  heart  is  distended  to  its 
maximum,  auxocardie.] 

Method. — The  cardo-pneumatic  movements — i.e.,  the  movement  of  the  respira- 
tory gases  dependent  on  the  movements  of  the  heart  and  great  vessels — may  be 
demonstrated  in  animals  and  man,  A  manometric  flame  may  be  used.  Insert  one 
limb  of  a  Y-tube  into  the  opened  trachea  of  an  animal,  while  the  other  limb  passes 
to  a  small  gas-jet,  and  connect  the  other  tube  with  a  gas-jet.  It  is  clear  that  the 
movements  of  the  heart  will  affect  the  column  of  gas,  and  thus  affect  the  flame. 
Large  animals  previously  curarised  are  best.  It  may  also  be  done  in  man  by 
inserting  the  tube  into  one  nostril,  while  the  other  nostril  and  the  mouth  are 
closed.  [A  simpler  and  less  irritating  plan  is  to  till  a  wide  curved  glass-tube  with 
tobacco  smoke,  and  insert  one  end  of  the  tube  into  one  nostril  while  the  other  nostril 
and  the  mouth  are  closed.  If  the  glottis  be  kept  open,  and  respiration  be  stopped, 
then  the  movements  of  the  column  of  smoke  within  the  tube  are  obvious.] 


Fig.  36. 

Landois'  cardio-pneumograph,  and  the  curves  obtained  therewith — A  and  B,  from 
man,  1  and  2,  correspond  to  the  periods  of  the  first  and  second  heart-sounds; 
C,  from  dog;  D,  method  of  using  the  apparatus. 

Cardio-PneumOgraph. — Ceradini    employed    a    special    instrument,     while 
Landois  uses  his  cardio-pneumograph  which  consists  of  a  tube  (D),  about  one  inch 


INFLUENCE   OF   RESPIRATORY  PRESSURE   ON   THE   HEART.         Ill 

in  diameter  and  six  to  eight  inches  in  length;  the  tube  is  bent  at  a  right  angle, 
and  communicates  with  a  small  metal  capsule  about  the  size  of  a  saucer  (T),  over 
which  a  membrane  composed  of  collodion  and  castor  oil  is  loosely  stretched.  To 
this  membrane  is  attached  a  glass-rod  (H)  used  as  a  writing-style,  wliich  records 
its  movements  on  a  glass-plate  (S)  moved  by  clock-work.  A  small  valve  (K)  is 
placed  on  the  side  of  the  tube  (D),  which  enables  the  experimenter  to  breathe 
when  necessarj'.  The  tube  (D)  is  held  in  an  air-tight  manner  between  the  lips, 
the  nostrils  being  closed,  the  glottis  open,  and  respiration  stopped.  Fig.  36, 
A,  B,  C,  are  curves  obtained  in  this  way.     In  them  we  observe — 

(a)  At  the  moment  of  the  first  sound  (1.),  the  respiratory  gases  undergo  a  sharp 
expiratory  movement,  because  at  the  moment  of  the  first  part  of  the  ventricular 
systole  the  blood  of  the  ventricle  has  not  left  the  thorax,  while  venous  blood  is 
streaming  into  the  right  auricle  through  the  venaj  cavaj,  and  because  the  dilating 
branches  of  the  pulmonary  artery  compress  the  accompanying  bronchi.  The 
blood  of  the  right  ventricle  lias  not  yet  left  the  thorax,  it  passes  merely  into 
the  pulmonary  circuit.  The  expiratory  movement  is  diminished  somewhat  by  {a) 
the  muscular  mass  of  the  ventricle  occupying  slightly  less  bulk  during  the  contrac- 
tion, and  (/3)  owing  to  the  thoracic  ca^^ity  being  slightly  increased  by  the  fifth 
intercostal  space  being  pushed  forward  by  the  cardiac  impulse. 

{b)  Iimnediately  after  (1. ),  there  follows  a  strong  inspiratory  current  of  the  respira- 
tory gases.  As  soon  as  the  blood  from  the  root  of  the  aorta  reaches  that  part  of 
the  aorta  lying  outside  the  thorax,  more  blood  leaves  the  chest  than  passes  into  it 
simultaneously  through  the  vena?  cava?. 

(c)  After  the  second  sound  (at  2. ),  indicated  sometimes  by  a  slight  depression  in 
the  apex  of  the  curve,  the  arterial  blood  accumulates,  and  hence  there  is  another 
expiratory  movement  in  the  curve. 

{d)  The  peripheral  wave-movements  of  the  blood  from  the  thorax  cause  another 
inspu-atory  movement  of  the  gases. 

(e)  More  blood  flows  into  the  chest  through  the  veins,  and  the  next  heart-beat 
occurs. 

60.  Influence  of  the  Respiratory  Pressure  on  the 
Dilatation  and  Contraction  of  the  Heart. 

The  variation  in  pressure  to  Avliicli  all  the  intra-thoracic  organs  are 
subjected,  owing  to  the  increase  and  decrease  in  the  size  of  the  chest 
caused  by  the  respiratory  movements,  exerts  an  influence  on  the  move- 
ments of  the  heart,  as  Avas  proved  by  Carson  in  1820,  and  by  Bonders 
in  1854.  Examine  first  the  relations  in  different  passive  conditions  of 
the  thorax,  when  the  glottis  is  open. 

The  diastolic  dilatation  of  the  cavities  of  the  heart  (excluding  the 
pressure  of  the  venous  blood  and  the  elastic  stretching  of  the  relaxed 
muscle-wall)  is  fundamentally  due  to  the  elastic  traction  of  the  lungs. 
This  is  stronger  the  more  the  lungs  are  distended  (inspiration),  and  is 
less  active  the  more  the  lungs  are  contracted  (expiration).  Hence  it 
follows  : — 

(1.)  When  the  greatest  possible  expiratory  effort  is  made  (of  course, 
with  the  glottis  open)  only  a  small  amount  of  blood  flows  into  the 
cavities  of  the  heart ;  the  heart  in  diastole  is  small  and  contains  a  small 


112  VALSALVA  AND  MULLEr's  EXPERIMENTS. 

amount  of  blood.  Hence  the  systole  must  also  be  small,  which  further 
gives  rise  to  a  small  pulse-beat. 

(2.)  On  taking  the  greatest  possible  inspiration,  and  therefore  causing 
the  greatest  stretching  of  the  elastic  tissue  of  the  lungs,  the  elastic 
traction  of  the  lungs  is,  of  course,  greatest — 30  mm.  Hg.  (Bonders). 
This  force  may  act  so  energetically  as  to  interfere  with  the  contraction 
of  the  thin-walled  atria  and  appendices,  in  consequence  of  which  these 
cavities  do  not  completely  empty  themselves  into  the  ventricles.  The 
heart  is  in  a  state  of  great  distension  in  diastole,  and  is  filled  with 
blood ;  nevertheless,  in  consequence  of  the  limited  action  of  the  auricles, 
only  small  pulse-beats  are  observed.  In  several  individuals  Bonders 
found  the  pulse  to  be  smaller  and  slower ;  afterwards  it  became  larger 
and  faster. 

(3.)  When  the  chest  is  in  a  position  of  moderate  rest,  whereby  the 
elastic  traction  is  moderate  (7'5  mm.  Hg. — Bonders),  we  have  the  condi- 
tion most  favourable  to  the  action  of  the  heart — sufficient  diastolic 
dilatation  of  the  cavities  of  the  heart,  as  well  as  unhindered  emptying 
of  them  during  systole. 

A  very  important  factor,  is  the  influence  exerted  upon  the  action  of 
the  heart,  by  the  voluntary  increase  or  diminution  of  the  intra-ihoracic 
pressure. 

(1.)  Valsalva's  Experiment. — If  the  thorax  is  fixed  in  the  position 
of  deepest  inspiration,  and  the  glottis  be  then  closed,  and  if  a  powerful 
expiratory  eff"ort  be  made  by  bringing  into  action  all  the  expiratory 
muscles,  so  as  to  contract  the  chest,  the  cavities  of  the  heart  are  so 
compressed  that  the  circulation  of  the  blood  is  temporarily  interrupted. 
In  this  expiratory  phase  the  elastic  traction  is  very  limited,  and  the  air 
in  the  lungs  being  under  a  high  pressure  also  acts  upon  the  heart  and 
the  intra- thoracic  great  vessels.  No  blood  can  pass  into  the  thorax 
from  without ;  hence  the  visible  veins  swell  up  and  become  congested, 
the  blood  in  the  lungs  is  rapidly  forced  into  the  left  ventricle  by  the 
compressed  air  in  the  lungs,  and  the  blood  soon  passes  out  of  the  chest. 
Hence  the  lungs  and  the  heart  contain  little  blood.  Hence  also  there 
is  a  greater  supply  of  blood  in  the  systemic  than  in  the  pulmonary 
circulation  and  the  heart.  The  heart-sounds  disappear,  and  the  pulse 
is  absent  (E.  H.  Weber,  Bonders). 

(2.)  J.  Miiller's  Experiment. — Conversely,  if  after  the  deepest  pos- 
sible expiration  the  glottis  be  closed,  and  the  chest  be  now  dilated  with 
a  great  inspiratory  effort,  the  heart  is  powerfully  dilated,  the  elastic 
traction  of  the  lungs,  and  the  very  attenuated  air  in  these  organs  act 
so  as  to  dilate  the  cavities  of  the  heart  in  the  direction  of  the  lungs. 
More  blood  flows  into  the  right  heart,  and  in  proportion  as  the  right 
auricle  and  ventricle  can  overcome  the  traction  outwards,  the  blood- 


INFLUENCE   OF  THE   RESPIRATION   ON   THE   HEART, 


113 


vessels  of  the  lungs  become  filled  with  blood,  and  thus  partly  occupy 
the  lung-space.  Much  less  blood  is  driven  out  of  the  left  heart,  so  that 
the  pulse  may  disappear.  Hence,  the  heart  is  distended  with  blood, 
and  the  lungs  are  congested,  while  the  aortic  system  contains  a  small 
amount  of  blood — i.e.,  the  systemic  circulation  is  comparatively  empty, 
while  the  heart  and  the  pulmonary  vessels  are  engorged  with  blood. 

In  normal  respiration,  the  air  in  the  lungs  during  inspiration  is 
under  slight  pressure,  while  during  expiration  the  pressure  is  higher, 
so  that  these  conditions  favour  the  circulation ;  inspiration  favours  the 
supply  of  blood  (and  lymph)  through  the  venee  cavse,  and  favours  the 
occurrence  of  diastole.  In  operations  where  the  axillary  or  jugular 
vein  is  cut,  air  may  be  sucked  into  the  circulation  during  inspiration, 
and  cause  death.  Expiration  favours  the  flow  of  blood  in  the  aorta 
and  its  branches,  and  aids  the  systolic  emptying  of  the  heart.  The 
arrangement  of  the  valves  of  the  heart  causes  the  blood  to  move  in  a 
definite  direction  through  it. 


Fis:  .37. 


Apparatus  for  demonstrating  the  action  of  inspiration,  II,  and  expiration,  I,  on 
the  heart  and  on  the  blood -stream — P,  p,  lungs  ;  H,  h,  heart ;  L,  I,  closed 
glottis  ;  M,  VI,  manometers  ;  E,  e,  ingoing  blood-stream,  vein  ;  A,  a,  outgoing 
blood-stream,  artery  ;  D,  diaphragm  during  expiration ;  d,  during  inspiration, 

8 


.114  INFLUENCE   OP  THE   RESPIRATION   ON   THE  HEART. 

The  elastic  traction  of  the  lungs  aids  the  lesser  circulation  through  the 
lungs  within  the  chest;  the  blood  of  the  pulmonary  capillaries  is 
exposed  to  the  pressure  of  the  air  in  the  lungs,  while  the  blood  in  the 
pulmonary  veins  is  exposed  to  a  less  pressure,  as  the  elastic  traction  of 
the  lungs,  by  dilating  the  left  auricle  favours  the  outflow  from  the 
capillaries  into  the  left  auricle.  The  elastic  traction  of  the  lungs  acts 
slightly  as  a  disturbing  agent  on  the  right  ventricle,  and,  therefore, 
on  the  movement  of  blood  through  the  pulmonary  artery,  owing  to 
the  overpowering  force  of  the  blood-stream  through  the  pulmonary 
artery,  as  against  the  elastic  traction  of  the  lungs  (Bonders). 

The  above  apparatus  (Fig.  37)  shows  the  effect  of  the  inspiratory  and  expiratory- 
movements  on  the  dilatation  of  the  heart,  and  on  the  blood-stream  in  the  large 
blood-vessels.  The  large  glass-vessel  represents  the  thorax;  the  elastic  mem- 
brane, D,  the  diaphragm  ;  P,  p,  the  lungs  ;  L,  the  trachea  supplied  with  a  stop-cock 
to  represent  the  glottis  ;  H,  the  heart ;  E,  the  venae  cavse  ;  A,  the  aorta.  If  the 
glottis  be  closed,  and  the  expiratory  phase  imitated  by  pushing  up  D  as  in  I,  the 
air  in  P,  P  is  compressed,  the  heart,  H,  is  compressed,  the  venous  valve  closes, 
the  arterial  is  opened,  and  the  fluid  is  driven  out  through  A.  The  manometer, 
M,  indicates  the  intrathoracic  pressure.  If  the  glottis  be  closed,  and  the 
inspiratory  phase  imitated,  as  in  II,  p,  p  and  h  are  dilated,  the  venous  valve 
opens,  the  arterial  valve  closes  ;  hence,  venous  blood  flows  from  e  into  the  heart. 
Thus,  inspiration  always  favours  the  venous  stream,  and  hinders  the  arterial ; 
while  expiration  hinders  the  venous,  and  favours  the  arterial  stream.  If  the 
glottis  L  and  I,  be  open,  the  air  in  P,  P,  p,  p  will  be  changed  during  the  respiratory 
movements  D  and  d,  so  that  the  action  on  the  heart  and  blood-vessels  will  be 
diminished,  but  it  will  still  persist,  although  to  a  much  less  extent. 


Tlie  Circulation. 


61.  The  Flow  of  Fluids  through  Tubes. 

Toricelli's  Theorem  (1643)  states  that  the  vekcity  of  efflux  (v)  of  a  ffuid- 
through  an  opening  at  the  bottom  of  a  cylindrical 
vessel — is  exactly  the  same  as  the  velocity  which  a  body 
falling  freely  would  acquire,  were  it  to  fall  from  the 
surface  of  the  fluid  to  the  base  of  the  orifice  of  the  out- 
flow. If  h  be  the  height  of  the  propelling  force,  thu 
velocity  of  efHux  is  given  by  the  formula — 


hJ 


■u  =  \/  "2  (J  h  (where  (j  =  9  "8  metre). 

The  rapidity  of  outflow  increases  (as  shown  experi- 
mentally) with  increase  in  the  height  of  the  propelling 
force,  li.  The  former  occurs  in  the  ratio,  1,  2,  3,  when  It 
increases  in  the  ratio,  ],  4,  9 — i.  c,  the  velocity  of  efflux 
is  as  the  square  root  of  the  height  of  the  propelling- 
force.  Hence,  it  follows  that  the  velocity  of  efflux 
depends  upon  the  height  of  the  liquid  above  the  orifice 
of  outflow,  and  not  upon  the  nature  of  the  fluid. 

Resistance. — Toricelli's  theorem,  however,  is  only 
valid  when  all  resistance  to  the  outflow  is  absent ;  but, 
in  fact,  in  every  physical  experiment  such  resistance 
exists.  Hence,  the  propelling  force,  h,  has  not  only  to 
cause  the  efflux  of  the  fluid,  but  has  also  to  overco7ne 
resistance.  These  two  forces  may  be  expressed  by  the 
heights  of  two  columns  of  water  placed  over  each  other — 
viz. ,  by  the  height  of  the  column  of  water  causing  the 
outflow,  F,  and  the  height  of  the  column,  D,  which 
overcomes  the  resistance  opposed  to  the  outflow  of  the  fluid.     So  that 

/i  =  F  -f  D. 


Fig.  38. 

Cylindrical  vessel  filled 
with  water — h,  height 
of  the  column  of  fluid ; 
D,  height  of  column  of 
fluid  required  to  over- 
come the  resistance ; 
and  F,  height  of 
column  of  fluid  caus- 
ing the  efflux. 


62.  Propelling  Force— Velocity  of  the  Current, 
and  Lateral  Pressure. 


In  the  case  of  a  fluid  flowing  through  a  tube,  which  it  fills  completely,  we  have 
to  consider  the  propelling  force,  h,  causing  the  fluid  to  flow  through  the  various 
sections  of  the  tube.  The  amount  of  the  propelling  force  depends  upon  two 
factors : — 

(1.)  On  the  velocity  of  the  current,  v  ; 

(2.)  On  the  pressure  (amount  of  resistance)  to  which  the  fluid  is  subjected  at  the 
various  parts  of  the  tube,  D. 

(1.)  The  velocity  of  the  current,  v,  is  estimated— (a. )  from  the  lumen,  I,  of  the 


116 


FLOW   OF  FLUIDS   THROUGH  TUBES. 


tube  ;  and  (1).)  from  the  quantity  of  fluid,  q,  wMcli  flows  through  the  tube  in 
the  unit  of  time.  So  that  v  =q  :  I.  Both  values,  q  as  well  as  I,  can  be  accurately 
measured.      (The  circumference  of  a  round  tube,   whose  diameter =c?  is  3'14.cZ. 


The   sectional  area   (lumen   of  the  tube)  is  l- 


314 


dr.)      Having  in  this   way 


determined  v,  from  it  we  may  calculate  the  height  of  the  column  of  fluid,  F,  which 
will  give  this  velocity — i.e.,  the   height  from  which  a  body  must  fall  in  vacuo, 

in  order  to  attain  the  velocity,  r,     In  this  case  F  —  j-^  (where  y  —  the  distance 


traversed  by  a  falling  body  in  1  sec. =4-9  metre). 


^9 


I         n 

Fig.  39. 


11 


A  cylindrical  vessel  flUed    with    water— or,    &,   outflow  tube,    along  which    are 
placed  at  intervals  vertical  tubes,  1,  2,  3,  to  estimate  the  pressure. 

(2.)  The  pressure,  D  (amount  of  resistance),   is  measured  directly  by  placing 
manometers  at  diflerent  parts  of  the  tube  (Fig.  39). 
The  propelling  force  at  any  part  of  the  tube  is 


or, 


h  =  F  +  D; 


4-0 


(Bonders). 


This  is  proved  experimentally  by  taking  a  tall  cylindrical  vessel,  A,  of  sufficient 
size,  which  is  kept  filled  with  water  at  a  constant  level,  7i.  The  outflow 
rigid  tube,  a,  b,  has  in  connection  vnth  it  a  number  of  tubes  placed  vertically 
I,  2,  3,  constituting  a  piezometer.  At  the  end  of  the  tube,  b,  there  is  an  opening 
with  a  short  tube  fixed  in  it,  from  which  the  water  issues  to  a  constant  height, 
provided  the  level  of  h  is  kept  constant.  The  height  to  which  it  rises  depends  on 
the  height  of  the  column  of  fluid  causing  the  velocity,  F.  As  the  pressure  in  the 
manometric  tubes,  'D\  D-,  D^,  can  be  read  ofi'  directly,  the  propelling  force  of  the 
water  at  the  sections  of  the  tubes,  I,  II,  III,  is— 

A  =  F  +  Di ;— F  +  D2;-F  +  D^. 

At  the  end  of  the  tube,  b,  where  I>*  =  0,h=F  +  0,  i.e.,  /t  =  F.  In  the  cylinder 
itself  it  is  the  constant  pressure,  h,  which  causes  the  movement  of  the  fluid. 

It  is  clear,  that  the  propelling  force  of  the  water  gradually  diminishes  as  we  pass 
from  the  part  where  the  fluid  passes  out  of  the  cylinder  into  the  tube  towards  the 
end  of  the  tube,  h.  The  water  in  the  pressure-cylinder,  falling  from  the  height,  h, 
only  rises  as  high  as  F  at  6.     This  diminution  of  the  propelling  power  is  due  to  the 


ESTIMATION   OF   RESISTANCE.  117 

presence  of  resistances,  which  oppose  the  current  in  the  tube,  i.e.,  part  of  the 
energy  is  transformed  into  heat.  As  the  propelling  power  at  b  is  represented  only 
by  F,  while  in  the  vessel  it  is  h,  the  difference  must  be  due  to  the  sum  of  the 
resistances,  D  ~  h-Y;  hence  it  follows  that  h  —  F  +  D  (Donders). 


Estimation  of  Resistance. 

Estimation  of  the  Eesistance.— ^Vhen  a  fluid  flows  through  a  tube  of 
uniform  calibre  the  propelling  force,  h,  diminishes  from  point  to  point  on  account 
of  the  uniformly  acting  resistance,  hence  the.  sum  of  the  resistances  in  the  whole 
tube  is  directly  proportional  to  its  length.  In  a  uniformly  wide  tube,  fluid  flows 
through  each  sectional  area  with  equal  velocity,  hence  v  and  also  F  are  equal  in 
all  parts  of  the  tube.  The  diminution  which  h  (propelling  force)  undergoes  can 
only  occur  from  a  diminution  of  pressure  D,  as  F  remains  the  same  throughout 
(and  /t  =  F  +  D).  Experiment  with  the  pressure-cylinder  shows,  that  as  a  matter 
of  fact,  the  pressure  towards  the  outflow  end  of  the  tube  becomes  gradually 
diminished. 

In  a  uniformly  ividc  tube,  the  height  of  the  pressure  in  the  manometers  expresses  the 
resistances  opposed  to  tlie  current  of  fluid,  ivhich  it  has  to  overcome  in  its  course 
from  the  jwint  investigated  to  the  free  orifice  of  efflux. 

Nature  of  the  Resistance. — The  resistance  opposed  to  the  flow  of  a  fluid, 
depends  upon  the  cohesion  of  the  particles  of  the  fluid  amongst  themselves.,  Dui-iug 
the  current,  the  outer  layer  of  fluid  which  is  next  the  wall  of  the  tube,  and  which 
moistens  it,  is  at  rest  ((4irard,  Poiseuille).  All  the  other  layers  of  fluid,  which 
may  be  represented  as  so  many  cylindrical  layers,  one  inside  the  other,  move  more 
rapidly  as  we  proceed  towards  the  axis  of  the  tube,  the  axial  thread  or  stream 
being  the  most  rapidly  mo\-ing  part  of  the  liquid.  On  account  of  the  movement  of 
the  cylindrical  layers,  one  within  the  other,  a  part  of  the  propelling  energy  must 
be  used  up.  The  amount  of  the  resistance  greatly  depends  upon  the  amount  of  the 
cohesive  force  which  the  particles  of  the  fluid  have  for  each  other  ;  the  more  firmly 
the  particles  cohere  with  each  other,  the  greater  will  be  the  resistance,  and  vice 
versa.  Hence,  the  sticky  blood-current  experiences  greater  resistance  than  water 
or  ether. 

Heat  diminishes  the  cohesion  of  the  particles,  hence  it  also  diminishes  the  resistance 
to  the  flow  of  a  current.  These  resistances  are  first  developed  by,  and  result  from, 
the  movement  of  the  particles  of  the  fluid,  they  being,  as  it  were,  torn  from  each 
other.  The  more  rapid  the  current,  therefore,  i.e.,  the  larger  the  number  of 
particles  of  fluid  which  are  pulled  asunder  in  the  unit  of  time,  the  greater  will  be 
the  sum  of  the  resistance.  As  already  mentioned,  the  layer  of  fluid  lying  next  the 
tube,  and  moistening  it,  is  at  rest,  hence  the  material  which  composes  the  tube 
exerts  no  influence  on  the  resistance. 


Effect  of  Tubes  of  Unequal  Calibre. 

Unequal  Diameter. — When  the  velocity  of  the  current  is  uniform,  the  resis- 
tance depends  upon  the  diameter  of  the  tube — the  smaller  the  diameter,  the  gi-eater 
the  resistance;  the  greater  the  diameter,  the  less  the  resistance.  The  resistance  in 
narrow  tubes,  however,  increases  more  rapidly  than  the  diameter  of  the  tube 
decreases,  as  has  been  proved  experimentally. 

In  tubes  of  unequal  calibre,  at  different  parts  of  their  course,  the  velocity  of  the 
current  varies — it  is  slower  in  the  wide  part  of  the  tube  and  more  rapid  in  the 


118  CURRENTS  THROUGH   CAPILLARY   TUBES. 

narrow  parts.  As  a  general  rule,  in  tubes  of  unequal  diameter  the  velocity  of 
the  current  is  inversely  proportional  to  the  diameter  of  the  corresponding  section 
of  the  tube ;  i.e.,  if  the  tube  be  cylindrical,  it  is  inversely  proportional  to  the  square 
of  the  diameter  of  the  circular  transverse  section.  In  tubes  of  uniform  diameter,  the 
propelling  force  of  the  moving  fluid  diminishes  uniformly  from  point  to  point,  but 
in  tubes  of  unequal  calibre  it  does  not  diminish  uniformly.  As  the  resistance  is 
greater  in  narrow  tubes,  of  course  the  propelhng  force  must  diminish  more  rapidly 
in  them  than  iu  wide  tubes.  Hence,  within  the  wide  parts  of  the  tube  the  pressure 
is  greater  than  the  sum  of  the  resistances  still  to  be  overcome,  while  in  the  narrow 
portions  it  is  less  than  these. 

Tortuosities  and  Bending  of  the  Vessels  add  new  resistance,  and  the  fluid 
presses  more  strongly  on  the  convex  side  than  on  the  concave  side  of  the  bend, 
and  there  the  resistance  to  the  flow  is  greater  than  on  the  concave  side. 

Division  of  a  tube  into  two  or  more  branches  is  a  source  of  resistance,  and 
diminishes  the  propelling  power.  When  a  tube  divides  into  two  smaller  tubes,  of 
course  some  of  the  particles  of  the  fluid  are  retarded,  while  others  are  accelerated 
on  account  of  the  unequal  velocities  of  the  difi"erent  layers  of  the  fluid.  Many 
particles  which  had  the  greatest  velocity  in  the  axial  layer  come  to  lie  more  towards 
the  side  of  the  tube  where  they  move  more  slowly ;  and  conversely  many  of  those 
lying  in  the  outer  layers  reach  the  centre,  where  they  move  more  rapidly.  Hence, 
some  of  the  propelling  force  is  used  up  in  this  process,  and  the  pulling  asunder  of 
the  particles  where  the  tube  divides  acts  in  a  similar  manner.  If  two  tubes  join 
to  form  07ie  tube,  new  resistance  is  thereby  caused  which  must  diminish  the 
propelling  force.  The  sum  of  the  mean  velocities  in  both  branches  is  independent 
of  the  oMgle  at  which  the  division  takes  place  ( Jacobson).  If  a  branch  be  opened 
from  a  tube,  the  principal  current  is  accelerated  to  a  considerable  extent,  no 
matter  at  what  angle  the  branch  may  be  given  off. 


63.  Currents  through  Capillary  Tubes. 

Poiseuille  proved  experimentally,  that  the  flow  in  the  capillaries  is  subject  to 
special  conditions — 

(1.)  The  quantity  of  fluid  which  flows  out  of  the  same  capillary  tube  is  pro- 
portional to  the  pressure. 

(2. )  The  time  necessary  for  a  given  quantity  of  fliiid  to  flow  out  (with  the  like 
pressure,  diameter  of  tube  and  temperature),  is  proportional  to  the  length  of 
the  tubes. 

(3.)  The  product  of  the  outflow  (other  things  being  equal)  is  as  the  fourth  power 
of  the  diameter. 

(4.)  The  velocity  of  the  current  is  proportional  to  the  pressure  and  to  the  square 
of  the  diameter,  and  inversely  proportional  to  the  length  of  the  tube. 

(5.)  The  resistance  in  the  capillaries  is  proportional  to  the  velocity  of  the  current. 


64.  Movement  of  Fluids  and  Wave-Motion  in 
Elastic  Tubes. 

(1.)  When  an  tLninterrupted  uniform  cxvcrent  flows  through  an  elastic  tube,  it 
follows  exactly  the  same  lavjs  as  if  the  tube  had  rigid  walls.  If  the  propelling 
power  increases  or  diminishes,  the  elastic  tubes  become  wider  or  narrower,  and 
they  behave,  as  far  as  the  movement  of  the  fluid  is  concerned,  as  wider  or  narrower 
rigid  tubes. 


MOVEMENT  OF   FLUIDS    IN   ELASTIC  TUBES.  119 

(2.)  Wave-Motion. — if,  however,  more  Huid  be  forced  i?i  jerks  into  an  elastic 
tube,  i.e.,  interruptedly — the  first  part  of  the  tube  dilates  suddenly,  corresponding 
to  the  quantity  of  fluid  propelled  into  it.  The  jerk  communicates  an  oscillatory 
movement  to  the  particles  of  the  fluid,  which  is  communicated  to  all  the  fluid 
particles  from  the  beginning  to  the  end  of  the  tube ;  a  positive  wave  is  thus  rapidly 
propagated  througliout  the  whole  length  of  the  tube.  If  we  imagine  the  elastic  tube 
to  be  closed  at  its  peripheral  end,  the  positive  wave  will  be  reflected  from  the 
point  of  occlusion,  and  it  may  be  propagated  to  and  fro  through  the  tube  uritil 
it  finally  disappears.  In  such  a  closed  tube  a  sudden  jet  of  fluid  produces  only  a 
wave-movement,  i.e.,  only  a  vibratory  movement,  or  an  alteration  in  the  shape 
of  the  liquid,  there  being  no  actual  translation  of  the  particles  along  the  tube. 

(8.)  If,  however,  fluid  be  pumped  interruptedly  or  by  jerks  into  an  elastic  tube 
filled  with  fluid,  in  which  there  is  already  a  continuous  current,  the  movement 
of  the  current  is  combined  with  the  wave-movement.  We  must  carefully  dis- 
tinguish the  movement  of  the  current  of  the  fluid,  i.e.,  the  translation  of  a  mass  of 
fluid  through  the  tube,  from  the  wave-movement,  the  oscillatory  movement,  or 
movement  of  change  of  form  in  the  column  of  fluid.  In  the  former,  the 
particles  are  actually  translated,  while  in  the  latter  they  merely  vibrate.  The 
current  in  elastic  tubes  is  slower  than  the  wave-movement,  which  is  propagated 
with  great  rapidity. 

This  last  case  obtains  in  the  arterial  system.  The  blood  in  the  arteries  is 
already  in  a  state  of  continual  movement,  directed  from  the  aorta  to  the  capillaries 
(movement  of  tlie  current  of  blood) ;  by  means  of  the  systole  of  the  left  ventricle 
a  quantity  of  fluid  is  siiddenly  pumped  into  the  aorta,  and  causes  a  positive  tvave 
(pulse-wave)  which  is  propagated  with  great  rapidity  to  the  terminations  of  the 
arteries,  while  the  current  of  the  blood  itself  moves  much  more  slowly. 

Rigid  and  Elastic  Tubes. — It  is  of  importance  to  contrast  the  movement 
of  fluids  in  rirjid  and  in  elastic  tubes.  If  a  certain  quantity  of  fluid  be  forced 
into  a  rigid  tube  under  a  certain  pressure,  the  same  quantity  of  fluid  will  flow 
out  at  once  at  the  other  end  of  the  tube,  provided  there  be  no  special  re- 
sistance. In  an  elastic  tube,  immediately  after  the  forcing  in  of  a  certain 
quantity  of  fluid,  at  first  only  a  small  quantity  flows  out,  and  the  remainder 
flows  out  only  after  the  propelling  foi'ce  has  ceased  to  act. 

If  an  equal  quantity  of  fluid  be  periodically  injected  into  a  rigid  tube,  with 
each  jerk  an  equal  quantity  is  forced  out  at  the  other  end  of  the  tube,  and  the 
outflow  lasts  exactly  as  long  as  the  jerk  or  the  contraction,  and  the  pause  betMeen 
two  periods  of  outflow  is  exactly  the  same  as  between  the  two  jerks  or  contractions. 
In  an  elastic  tube  it  is  different,  as  the  outflow  continues  for  a  time  after  the 
jerk;  hence,  it  follows  that  a  continuous  outflow  current  will  be  produced  in 
elastic  tubes,  when  the  time  between  two  jerks  is  made  shorter  than  the  duration 
of  the  outflow  after  the  jerk  has  been  completed.  When  fluid  is  pumped 
periodically  into  rigid  tubes,  it  causes  a  sharp  abrupt  outflow  isochronous  with 
the  inflow,  and  the  outflow  becomes  continuous  only  when  the  inflow  is 
continuous  and  uninterrupted.  In  elastic  tubes,  an  intermittent  current  under 
the  above  conditions  causes  a  continuous  outflow  which  is  increased  with  the 
systole  or  contraction. 


65.  Structure  and  Properties  of  the  Blood- Vessels. 

In  the  body  the  large  vessels  carry  the  blood  to  and  from  the  various 
tissues  and  organs,  while  the  thin-walled  capillaries  bring  the  blood  into 


120 


STRUCTURE   OF  ARTERIES. 


intimate  relation  with  the  tissues.  Through  the  excessively  thin  walls 
of  the  capillaries  the  fluid  part  of  the  blood  transudes,  to  nourish  the 
tissues  outside  the  capillaries.  [At  the  same  time  fluids  pass  from  the 
tissues  into  the  blood.  Thus,  there  is  an  exchange  between  the  blood 
and  the  fluids  of  the  tissues.  The  fluid  after  it  passes  into  the  tissues 
constitutes  the  lymph,  and  acts  like  a  stream  irrigating  the  tissue 
elements,] 

I.  The  Arteries  are  distinguished  from  veins  by  their  thicker 
walls,  due  to  the  greater  development  of  smooth  muscular  and 
elastic  tissues — the  middle  coat  (tunica  media)  of  the  arteries  is 
specially  thick,  while   the  outer  coat  (t.  adventitia)  is  relatively  thin. 

[The   absence   of    valves    is     by    no 
means  a  characteristic  feature.] 

The  arteries  consist  of  three  coats 
(Fig.  40).  (1.)  The  Tunica  intima, 
or  inner  coat,  consists  of  a  layer  of 
(a)  irregular,  long,  fusiform  nucleated 
vsquamous  cells  forming  the  exces- 
sively thin  transparent  endothelium 
(His,  1866),  immediately  in  contact 
with  the  blood-stream.  [Like  other 
endothelial  cells,  these  cells  are  held 
together  by  a  cement  substance  which 
is  blackened  by  the  action  of  silver 
nitrate.] 

Outside  this  lies  a  very  thin,  more 
or  less  fibrous,  layer  —  suh-epitheVMl 
luijer — in  which  numerous  spindle  or 
branched  protoplasmic  cells  lie  em- 
bedded within  a  corresponding  system 
of  plasma  canals.  Outside  this  is  an 
elastic  lamina  {h),  which  in  the  smallest 
arteries  is  a  structureless  or  fil^rous 
elastic  membran  e — in  arteries  of  medium 
lamina;  c,  circular  muscular  fibres  size  it  is  a  fenestrated  membrane  (Henle), 
of  the  middle  coat;  rZ,  the  comiective  ^^hile  in  the  /rt?-r/csi  arteries  there  may 
tissue  outer  coat  (T.  adventitia).        ,  ,    ,  r     i     j.-      i       • 

be  several  layers  of  elastic  laminae  or 

fenestrated  elastic  membrane  mixed  with  connective  tissue.  [In  some 
arteries  the  elastic  membrane  is  distinctly  fibrous,  the  fibres  being 
chiefly  arranged  longitudinally.  It  may  be  strij^ped  off,  when  it  forms 
a  brittle  elastic  membrane,  which  has  a  great  tendency  to  curl  up  at 
its  margins.  In  a  transverse  section  of  a  middle-sized  artery  it 
appears  as  a  bright  wavy  line,  but  the  curves  are  probably  produced 


Fig.  40. 

Small  artery  to  show  the  various 
layers  -which  compose  its  walls — 
«,  endothelium;  h,  internal  elastic 


STRUCTURE   OF   ARTERIES.  121 

by  the  partial  collapse  of  the  vessel.  It  forms  an  important  guide  to 
the  pathologist  in  enabling  him  to  determine  which  coat  of  the 
artery  is  diseased.] 

In  middle-sized  and  large  arteries  a  few  non-striped  muscular  fibres 
are  disposed  longitudinally  between  two  elastic  plates  or  lamina?  (K. 
Bardeleben).  Along  with  the  circular  muscular  fibres  of  the  middle 
coat,  they  may  act  so  as  to  narroAv  the  artery,  and  they  may  also  aid  in 
keeping  the  lumen  of  the  vessel  open  and  of  uniform  calibre.  It 
is  not  probable  that  when  they  act  by  themselves  they  dilate  the 
vessel. 

(2.)  The  Tunica  media,  or  middle  coat,  contains  much  non-striped 
muscle  (c),  which  in  the  smallest  arteries  consist  of  transversely  disposed 
non-striped  muscular  fibres  lying  between  the  endothelium  and  the 
T.  adventitia,  while  a  finely  granular  tissue  with  few  elastic  fibres  forms 
the  bond  of  union  between  them.  As  we  proceed  from  the  very 
smallest  to  the  small  arteries,  the  number  of  muscular  fibres  becomes 
so  great  as  to  form  a  well-marked  fibrous  ring  of  non-striped  muscle,  in 
which  there  is  comparatively  little  connective  tissue.  In  the  large 
arteries  the  amount  of  connective  tissue  is  considerably  increased,  and 
between  the  layers  of  fine  connective  tissue  numerous  (as  many  as 
50)  thick,  elastic  fibrous  or  fenestrated  laminae  are  concentrically 
arranged. 

A  few  non-striped  fibres  lie  scattered  amongst  these,  and  some  of 
them  are  arranged  transversely,  while  a  few  have  an  oblique  or  longi- 
tudinal direction. 

The  first  part  of  the  aorta  and  pulmonary  artery,  and  the  retinal  arteries  are 
devoid  of  muscle.  The  descending  aorta,  common  iliac,  and  popliteal  have  longi- 
tudinal fibres  between  the  transverse  ones.  Longitudinal  bundles  lying  inside  the 
media  occur  in  the  renal,  splenic,  and  internal  spermatic  arteries.  Longitudinal 
bundles  occur  both  on  the  outer  and  inner  surfaces  of  the  umbilical  arteries,  which 
are  very  muscular. 

(3.)  The  Tunica  adventitia,  or  outer  coat,  in  the  smallest  arteries 
consists  of  a  structureless  membrane  with  a  few  connective  tissue 
corpuscles  attached  to  it ;  in  somewhat  larger  arteries  there  is  a  layer 
of  fine  fibrous  elastic  tissue  mixed  with  bundles  of  fibrillar  connective 
tissue  ((/).  In  arteries  of  middle  size,  and  in  the  largest  arteries  the 
chief  mass  consists  of  bundles  of  fibrillar  connective  tissue  containing 
connective  tissue  corpuscles.  The  bundles  cross  each  other  in  a  variety 
of  directions,  and  fat  cells  often  lie  between  them.  Next  the  media 
there  are  numerous  fibrous  or  fenestrated  elastic  lamellae.  In  medium 
sized  and  small  arteries  the  elastic  tissue  next  the  media  takes  the 
form  of  an  independent  elastic  membrane  (Henle's  external  elastic 


122 


STRUCTURE   OF   CAPILLARIES. 


Fig.  41. 

Capillaries — The  outlines  of  the  endothelial  cells 
marked  off  from  each  other  by  the  cement 
which  is  blackened  by  the  action  of  silver 
nitrate.     The  nuclei  of  the  cells  are  obvious. 


membrane).     Bundles  of  non-striped  muscle,  arranged  longitudinally, 

occur  in  the  adventitia  of 
the  arteries  of  the  penis, 
and  in  the  renal,  splenic, 
spermatic,  iliac,  hypogas- 
tric, and  superior  mesen- 
teric arteries. 

II.  The  Capillaries,  while 
retaining  their  diameter, 
divide  and  reunite  so  as 
to  form  net-works,  whose 
shape  and  arrangement 
differ  considerably  in  dif- 
ferent tissues.  The  diame- 
ter of  the  capillaries  varies 
considerably,  but  as  a 
general  rule,  it  is  such  as 
to  admit  freely  a  single 
row  of  blood-corpuscles. 
In  the  retina  and  muscle 
the  diameter  is  5  -  6  /x,  and  in  bone-marrow,  liver,  and  choroid 
10  —  20  fx.  The  tubes  consist  of  a  single  layer  of  transparent,  ex- 
cessively thin  nucleated  endothelial  cells  joined  to  each  other  by  their 
margins  (Hoyer,  Auerbach,  Eberth,  Aeby,  1865). 

[The  nuclei  contain  a  well-marked  intra-nuclear  plexus  of  fibrils, 
like  other  nuclei.]  The  cells  are  more  fusiform  in  the  smaller  capil- 
laries and  more  polygonal  in  the  larger.  The  body  of  the  cells 
presents  the  characters  of  very  faintly  refractive  protoplasm,  but  it  is 
doubtful  whether  the  body  of  the  cell  is  endowed  with  the  property  of 
contractility. 

Action  of  Silver  Nitrate. — If  a  dilute  solution  {\  per  cent.)  of 
silver  nitrate  be  injected  into  the  blood-vessels,  the  cement  substance 
of  the  epithelium  [and  of  the  muscular  fibres  as  well]  is  revealed  by 
the  presence  of  the  black  "  silver-lines."  The  blackened  cement  sub- 
stance shows  little  specks  and  large  black  slits  at  different  points. 
It  is  not  certain  whether  these  are  actual  holes  (J.  Arnold)  through 
which  colourless  corpuscles  may  pass  out  of  the  vessels,  or  are  merely 
larger  accumulations  of  the  cement  substance. 

[Arnold  called  these  small  areas  in  the  black  silver  lines  when  they  were  large 
stomata,  and  when  small  stigmata.  They  are  most  numerous  after  venous 
congestion,  and  after  the  disturbances  which  follow  inflammation  of  a  part 
(Cohnheim,  Winiwarter).  They  are  not  always  present.  The  existence  of  cement 
substance  between  the  cells  may   also  be  inferred  from  the  fact  that  indigo- 


STRUCTURE   OF   VEINS. 


123 


sulphate  of  soda  is  deposited  in  it  (Thoma),  and  particles  of  cinnabar  and  China 
ink  are  fixed  in  it,  when  these  substances  are  injected  into  the  blood  (Foa).] 

Fine  anastomosing  fibrils  derived  from  non-meduUated  nerves 
terminate  in  small  end-buds  in  relation  with  the  capillary  wall; 
ganglia  in  connection  with  capillary  nerves  occur  only  in  the  region 
of  the  sympathetic  (Bremer  and  Waldeyer). 

[If  a  capillary  is  examined  in  a  perfectly  fresh  condition  (while 
living)  and  Avithout  the  addition  of  any  reagent,  it  is  impossible  to 
make  out  any  line  of  demarcation  between  adjacent  cells  owing  to 
the  uniform  refractive  index  of  the  entire  wall  of  the  tube.] 

The  small  vessels  next  in  size  to  the  capillaries  and   continuous 
with    them    have    a     completely 
structureless  covering  in   addition 
to  the  endothelium. 

III.  The  Veins  are  generally 
distinguished  from  the  arteries  by 
their  lumen  being  icidc}'  than  the 
lumen  of  the  corresponding 
arteries ;  their  walls  are  thinner 
on  account  of  the  smaller  amount 
of  non-striped  muscle  and  elastic 
tissue  (the  non-striped  muscle  is 
not  unfrequently  arranged  longi- 
tudinally in  veins).  They  are 
also  more  extensile  (with  the  same 
strain).  The  adventitia  is  usually 
the  thickest  coat. 

The  occurrence  of  valves  is 
limited  to  the  veins  of  certain 
areas.  (1.)  The  intima  consists 
of  a  layer  of  sJwrtcr  and  broader 
endothelial  cells,  under  which  in 
the  smallest  veins  there  is  a 
structureless  elastic  membrane, 
sub-ejnthelial  layer,  which  is  fibrous 
in  veins  somewhat  larger  in  size, 
but  in  all  cases  is  thinner  than  in 
the  arteries.  In  large  veins  it 
may  assume  the  characters  of  a 
fenestrated  membrane,  which  is 
double  in  some  parts  of  the 
crural  and  iliac  veins.  Isolated  muscular  fibres  exist  in  the  intima 
of  the  femoral  and  popliteal  veins. 


Fig.  42. 

Longitudinal  section  of  a  vein  at  the 
level  of  a  valve— «,  hyaline  layer  of 
the  internal  coat;  b,  elastic  lamina; 
c,  groups  of  smooth  muscular  fibres 
divided  transversely;  d,  longitudinal 
muscular  fibres  in  the  adventitia. 


124  STRUCTURE   OF   VEINS. 

(2.)  The  media  of  the  larger  veins  consists  of  alternate  layers  of 
elastic  and  muscular  tissue  united  to  each  by  a  considerable  amount  of 
connective  tissue,  but  this  coat  is  always  thinner  than  in  the  corres- 
ponding arteries.  This  coat  diminishes  in  the  following  order  in 
the  following  vessels — popliteal,  veins  of  the  lower  extremity,  veins 
of  the  upper  extremity,  superior  mesenteric,  other  abdominal  veins, 
hepatic,  pulmonary,  and  coronary  veins.  The  following  veins  contain 
no  muscle — veins  of  bone,  central  nervous  system,  and  its  membranes, 
retina,  the  superior  cava,  with  the  large  trunks  that  open  into  it, 
the  upper  part  of  the  inferior  cava.  Of  course,  in  these  cases,  the 
media  is  very  thin.  In  the  smallest  veins  the  media  is  formed  of 
fine  connective  tissue,  with  very  few  muscular  fibres  scattered  in 
the  inner  part. 

(3.)  The  adventitia  is  thicker  than  that  of  the  corresponding 
arteries  j  it  contains  much  connective  tissue  usually  arranged  longi- 
tudinally, and  not  much  elastic  tissue.  Longitudinally  arranged 
muscular  fibres  occur  in  some  veins  (renal,  portal,  inferior  cava  near 
the  liver,  veins  of  the  lower  extremities).  The  valves  consist  of 
fine  fibrillar  connective  tissue  with  branched  cells.  An  elastic  net- 
work exists  on  their  convex  surface,  and  both  surfaces  are  covered 
by  endothelium.  The  valves  contain  many  muscular  fibres  (Fig.  42). 
[Ranvier  has  shown  that  the  shape  of  the  epithelial  cells  covering 
the  two  surfaces  of  the  valves  differs.  On  the  side  over  which  the 
blood  passes,  they  are  more  elongated  than  on  the  cardiac  side  of 
the  valve,  where  the  long  axes  of  the  cell  are  placed  transversely.] 

The  sinuses  of  the  dura  mater  are  spaces  covered  with  endothelium.  The  spaces 
are  either  duplicatures  of  the  membrane,  or  channels  in  the  substance  of  the  tissue 
itself. 

Cavernous  spaces  we  may  imagine  to  arise  by  numerous  divisions  and  anasto- 
moses of  tolerably  large  veins  of  unequal  calibre.  The  vascular  wall  appears  to 
be  much  perforated  and  like  a  sponge,  the  internal  space  being  traversed  by  threads 
and  strands  of  tissue,  which  are  covered  with  endothelium  on  their  surfaces,  that 
are  in  contact  with  the  blood.  The  surrounding  wall  consists  of  connective  tissue 
which  is  often  very  tough,  as  in  the  corpus  cavernosum,  and  it  not  unfrequently 
contains  non -striped  muscle. 

Cavernous  Formations  of  an  analogous  nature  on  arteries,  are  the 
carotid-gland  of  the  frog,  and  a  similar  structure  on  the  pulmonary 
arteries  and  aorta  of  the  turtle,  and  the  coccygeal-gland  of  man  (Luschka). 
This  structure  is  richly  supplied  with  sympathetic  nerve-fibres,  and  is  a 
convoluted  mass  of  ampullated  or  fusiform  dilatations  of  the  middle 
sacral  artery  (Arnold),  surrounded  and  permeated  by  non-striped 
muscle  (Eberth). 

Vasa  Vasorum. — [These  are  small  vessels  which  nourish  the  coats  of  the 
arteries  and  veins.     They  arise  from  one  part  of  a  vessel  and  enter  the  walls  of 


PHYSICAL   PROPERTIES  OF  THE  BLOOD-VESSELS.  125  . 

the  same  vessel,  or  another  at  a  lower  level.  They  break  up  chiefly  in  the  outer 
coat,  and  none  enter  the  inner  coat.]  In  structure  they  resemble  other  small 
blood-vessels,  and  the  blood  circulating  in  the  arterial  or  venous  wall  is  returned 
by  small  veins. 

Intercellular  blood-channels. — Intercellular  blood-channels  of  narrow  calibre 
and  without  walls  occur  in  the  granulation  tissue  of  healing  wounds.  At  first 
blood-plasma  alone  is  found  between  the  formative  cells,  but  afterwards  the  blood- 
current  forces  blood-corpuscles  through  the  channels.  The  first  blood-vessels  in 
the  developing  chick  are  formed  in  a  similar  way  from  the  formative  cells  of  the 
mesoblast. 

Properties  of  the  Blood-Vessels. — The  larger  blood-vessels  are 
cylindrical  tubes  composed  of  several  layers  of  various  tissues,  more 
especially  elastic  tissue  and  j^^^f'in  muscular  fibres,  and  the  whole  is  lined 
by  a  smooth  layer  of  epithelium.  One  of  the  most  important  properties 
is  the  CONTRACTILITY  of  the  vascular  wall,  in  virtue  of  which  the 
blood-vessel  becomes  contracted,  so  that  the  calibre  of  the  vessel  and, 
therefore,  the  supply  of  blood  to  a  part  are  altered.  The  contractility 
is  due  to  the  plain  muscular  fibres  which  are,  for  the  most  part, 
arranged  circularly.  It  is  most  marked  in  the  small  arteries,  and  of 
course  is  absent  where  no  muscular  tissue  occurs.  The  amount  and 
intensity  of  the  contraction  depend  upon  the  development  of  the 
muscular  tissue ;  in  fact,  the  two  go  hand-in-hand.  [If  an  artery  be 
exposed  in  the  living  body  it  soon  contracts  under  the  stimulus  of  the 
atmosphere  (J.  Hunter)  acting  upon  the  muscular  fibres.] 

[Action  of  Alkalies  and  Acids  on  the  Vascular  System.— Gaskell  finds 

that  very  dilute  alkalies  and  acids  have  a  remarkable  effect  on  the  blood-vessels 
and  also  upon  the  heart.  A  very  dilute  solution  of  lactic  acid  (1  part  to  10,000 
parts  of  saline  solution),  passed  through  the  blood-vessels  of  a  frog,  always  enlarges 
the  calibre  of  the  blood-vessels,  while  an  alkaline  solution  (1  part  sodium  hydrate 
to  10,000  or  20,000  parts  saline  solution)  always  diminishes  their  size,  usually  to 
absolute  closure,  and  indeed  the  artificial  constriction  of  the  blood-vessels  may  be 
almost  complete.  These  fluids  are  antagonistic  to  each  other  as  far  as  regards 
their  action  on  the  calibre  of  the  arteries.  Microscopic  observations  which  con- 
firmed these  results,  were  also  made  on  the  blood-vessels  of  the  mylohyoid  muscle 
of  the  frog.  Dilute  alkaline  solutions  act  on  the  heart  in  the  same  way.  After 
a  series  of  beats,  the  ventricle  stops  beating,  the  stand-still  being  in  a  state  of  con- 
traction. Very  dilute  lactic  acid  causes  the  ventricle  to  stand  still  in  the  position 
of  complete  relaxation.  The  action  of  the  acid  and  alkali  solutions  are  antagonistic 
in  theh'  action  on  the  ventricle.  Gaskell  attaches  considerable  importance  to  the 
"  tonic  "  and  "  atonic  "  conditions  of  the  whole  vascular  system  produced  by  very 
dilute  solutions  of  alkalies  and  acids  respectively.] 

That  the  capillaries  undergo  dilatation  and  contraction,  owing  to 
variations  in  size  of  the  protoplasmic  elements  of  their  walls,  must  be 
admitted. 

Strieker  has  described  capillaries  as  "protoplasm  in  tubes,"  and  observed  that 
they  exhibited  movements  when  stimulated  in  living  animals.  Golubew  described 
an  active  state  of  contraction  of  the  capillary  wall,  but  he  regarded  the  nuclei  as 


126  PHYSICAL  PROPERTIES   OF  THE   BLOOD-VESSELS. 

the  parts  which  underwent  change.  Tarchanoff  found  that  mechanical  or  electrical 
stimulation  caused  a  change  in  the  shape  and  size  of  the  nuclei,  so  that  he  regards 
these  as  the  actively  contractile  parts.  [Severini  also  attaches  great  importance 
to  the  contractility  of  the  capillaries.  ]  Strieker's  observations  were  made  on  the 
capillaries  of  tadpoles.  These  phenomena  became  less  marked  as  the  animal 
became  older.  Rouget  observed  the  same  result  in  the  capillaries  of  new-born 
mammals.  As  the  capillaries  are  excessively  thin  and  delicate,  and  as  they  are 
soft  structures,  it  is  obvious  that  the  form  of  the  individual  cells  must  depend  to  a 
considerable  extent  upon  the  degree  to  which  the  vessels  are  filled  with  blood.  In 
vessels  which  are  distended  with  blood  the  endothelial  cells  are  flattened,  but  when 
the  capillaries  are  collapsed,  they  project  more  or  less  into  the  lumen  of  the  vessel 
(Renaut). 

[It  is  a  well-known  fact  that  the  capillaries  present  great  variations  in  their 
diameter  at  different  times.  As  these  variations  are  usually  accompanied  by  a 
corresponding  contraction  or  dilatation  of  the  arterioles,  it  is  usually  assumed  that 
the  variations  in  the  diameter  of  the  capillaries  are  due  to  differences  of  the  pres- 
sure within  the  capillaries  themselves — viz.,  to  the  elasticity  of  their  walls.  Every 
one  is  agreed  that  the  capillaries  are  very  elastic,  but  the  experiments  of  Roy  and 
Graham  Brown  show  that  they  are  contractile  as  well  as  elastic,  and  these 
observers  conclude  that  under  normal  conditions,  it  is  by  the  contractility  of  the 
capillary  wall  as  a  whole  that  the  diameter  of  these  vessels  is  changed,  and  to  all 
appearance  their  contractihty  is  constantly  in  action.  "The  individual  capillaries 
(in  all  probability)  contract  or  expand  in  accordance  with  the  requirements  of  the 
tissues  through  which  they  pass.  The  regulation  of  the.vascular  blood-flow  is  thus 
more  complete  than  is  usually  imagined  "  (Roy  and  Graham  Brown).] 

Physical  Properties. — Amongst  the  physical  properties  of  the  blood- 
vessels. Elasticity  is  the  most  important ;  their  elasticity  is  small  in 
amount,  i.e.,  they  offer  little  resistance  to  any  force  applied  to  them  so 
as  to  distend  or  elongate  them,  but  it  is  perfect  in  quality,  i.e.,  the 
blood-vessels  rapidly  regain  their  original  size  and  form  after  the  force 
distending  them  is  removed. 

[The  elasticity  of  the  arteries  is  of  the  utmost  importance  in  aiding  the  conversion 
of  the  interrupted  flow  of  the  blood  in  the  large  arteries  into  a  uniform  flow  in 
the  capillaries.  E.  H.  Weber  compared  the  elastic  wall  of  the  arteries  with  the 
air  in  the  air-chamber  of  a  fire-engine.  In  both  cases  an  elastic  medium  is  acted 
upon — the  air  in  the  one  case  and  the  elastic  tissue  in  the  other — which  in  turn 
presses  upon  the  fluid,  propelling  it  onwards  continually,  while  the  action  of  the 
pump  or  the  heart,  as  the  case  may  be,  is  intermittent.] 

According  to  E.  H.  Weber,  Volkmann,  and  Wertheim,  the  elongation  of  a  blood- 
vessel (and  most  moist  tissues)  is  not  proportional  to  the  weight  used  to  extend  it, 
the  elongation  being  relatively  less  with  a  large  weight  than  with  a  small  one,  so 
that  the  curve  of  extension  is  nearlj"-  [or,  at  least,  bears  a  certain  relation  to]  a 
hyperbola. 

According  to  Wundt,  we  have  not  only  to  consider  the  extension  produced  at 
first  by  the  weight,  but  also  the  subsequent  "elastic  after-effect," -which,  occurs 
gradually.  The  elongation  which  occurs  during  the  last  few  moments  occurs  so 
slowly  and  so  gradually  that  it  is  well  to  observe  the  effect  by  means  of  a  magni- 
fying lens.  Variations  from  the  general  law  occur  to  this  extent,  that  if  a  certain 
weight  is  exceeded,  less  extension,  and,  it  may  be,  permanent  elongation  of  the 
artery  not  unfrequently  occur.  K.  Bardeleben  found,  especially  in  veins 
elongated  to  40  or  50  per  cent,  of  their  original  length,  that  when  the  weight 
employed  increased  by  an  equal  amount  each  time,  the  elongation  was  proportional 


THE  PULSE.  127 

to  the  square-root  of  the  weight.  This  is  apart  from  any  elastic  after-effect.  Veins 
may  be, extended  to  at  least  50  per  cent,  of  their  length  without  passing  the  limit 
of  their  elasticity. 

[Roy  has  made  careful  experiments  upon  the  elastic  properties  of  the  arterial 
wall.  A  portion  of  an  artery,  so  that  it  could  be  distended  by  any  desired  internal 
pressure,  was  inclosed  in  a  small  vessel  containing  olive  oil.  The  small  vessel  with 
oil  was  arranged  in  the  same  way  as  in  Fig.  33  for  the  heart.  The  variations  of 
the  contents  were  recorded  by  means  of  a  lever  writing  on  a  revolving  cylinder. 
The  aorta  and  other  large  arteries  were  found  to  be  most  elastic  and  most  distensible 
at  pressures  corresponding  more  or  less  exactly  to  their  normal  blood-pressure, 
while  in  veins  the  relation  between  internal  pressure  and  the  cubic  capacity  is  very 
different.  In  them  the  maximum  of  disteusibility  occurs  with  pressures  imme- 
diately above  zero.  Speaking  generally,  the  cubic  capacity  of  an  artery  is  greatly 
increased  by  raising  the  intra-arterial  tension,  say  from  zero  to  about  the  normal 
internal  pressure  which  the  artery  sustains  during  life.  Thus  in  the  rabbit  the 
caj)acity  of  the  aorta  was  quadra/ded  by  raising  the  intra-arterial  pressure  from 
zero  to  200  mm.  Hg.,  while  that  of  the  carotid  was  more  than  six  times  as  great 
at  that  pressure  as  it  was  in  the  undistended  condition.  The  pulmonary  artery  is 
distinguished  by  its  excessive  elastic  disteusibility.  Its  capacity  (rabbit)  was 
increased  more  than  twelve  times  on  raising  the  internal  pressure  from  zero  to 
about  36  mm.  Hg.  Veins,  on  the  other  hand,  are  distinguished  by  the  relatively 
small  increase  iu  their  cubic  capacity  produced  by  greatly  raising  the  internal 
pressure,  so  that  the  enormous  changes  in  the  capacity  of  the  veins  during  life,  are 
due  less  to  differences  in  the  pressure  than  to  the  great  differences  in  the  quantity 
of  blood  which  they  contain  (Roy).] 

Pathological. — Interference  with  the  nutrition  of  an  artery  alters  its  elasticity 
[and  that  in  cases  where  no  structural  changes  can  be  found].  Marasmus  pre- 
ceding death  causes  the  arteries  to  become  wider  than  normal  (Roy).  Age  also 
influences  their  elasticity — in  some  old  people  they  become  atheromatous  and 
even  calcified.  [The  ratio  of  expansion  of  strips  of  the  aortic  wall  to  the  weights 
employed  to  stretch  them,  remains  much  the  same  from  childhood  up  to  a  certain 
age  (Roy).] 

Cohesion. — Blood-vessels  are  endowed  with  a  very  large  amount  of 
cohesion,  in  virtue  of  which  they  are  able  to  resist  even  considerable 
internal  pressure  without  giving  way.  The  carotid  of  a  sheep  is  ruptured 
only  when  fourteen  times  the  usual  pressure  it  is  called  upon  to  bear  is 
put  upon  it  (Volkmann).  A  greater  pressure  is  required  to  rupture  a 
vein  than  an  artery  with  the  same  thickness  of  its  wall. 


66.  The  Pulse— Historical. 

Although  the  movement  of  the  pulse  in  the  superficially  placed  arteries  was 
known  to  the  ancients,  still  the  pulse,  as  it  was  affected  by  disease,  was  more 
studied  by  the  older  physicians  than  the  normal  pulse.  Hippocrates  (460  to  377 
B.C.)  speaks  of  the  former  as  o-4)Dyuos,  while  Herophilus  (300  B.C.)  contrasted  the 
normal  pulse  (-n-aXjUos)  with  the  pulse  of  disease  (o-t/juy/ios).  He  lays  special  stress 
upon  the  relative  time  occupied  by  the  dilatation  and  contraction  of  the  arterial 
tube,  and  compares  these  phenomena  with  the  notes  of  music.  He  established  the 
fact  that  the  rhythm  of  the  pulse  varies  in  the  newly-born,  in  the  adult,  and  in 
the  aged.  Further,  he  distinguished  the  size,  fulness,  quickness,  &n^ frequency  of 
the  pulse.     Erasistratus  (t  280  B.C.),  a  contemporary  of  Herophilus,  made  correct 


128 


INSTRUMENTS  FOR  INVESTIGATING  THE  PULSE. 


observations  on  the  pulse-wave.  He  points  out  tliat  the  pulse  occurs  sooner  in 
arteries  near  the  heart  than  in  those  placed  further  away  from  it,  because  the  pulse 
proceeding  from  the  heart  passes  towards  the  periphery.  Erasistratus  placed  a 
cannula  in  the  course  of  an  artery,  and  he  found  that  the  pulse  could  still  be  felt 
on  the  distal  side  of  this  point.  Archigenes  gave  the  name  dicrotic  pulse  to  a 
condition  which  he  had  observed  in  febrile  conditions.  Galen  (131  to  202  A.D.) 
gave  more  exact  details  as  to  the  relations  of  the  dilatation  and  contraction  of  the 
arteries  during  the  movement  of  the  pulse,  and  supplied  much  information  on  the 
pulse-rhythm,  and  the  influence  of  temperament,  age,  sex,  period  of  the  year, 
climate,  sleep  and  waking,  cold  and  warm  baths,  on  its  rate  and  other  qualities. 
Cusanus  (1565)  was  the  first  person  to  count  the  pulse-beats  with  the  aid  of  a 
watch. 

67.  Instruments  for  Investigating  the  Pulse. 

The  individual  phases  of  the  movement  of  the  pulse  could  only  be 
accurately  investigated  by  the  application  of  instruments  to  the  arteries. 

(1.)  Poiseuille's  Box  Pulse-Measurer  (1829).— An  artery  (Fig.  43,  a,  a)  is 

exposed  and  placed  in  an  oblong  box  (K,  K)  filled  with  an  indifferent  fluid.  A 
vertical  tube  with  a  scale  attached  communicates  with  the  interior  of  the  box. 
The  column  of  fluid  undergoes  a  variation  with  every  pulse-beat. 


Fig.  43. 
Poiseuille's  pulse-measurer — a,  a,  exposed  artery  ;  K,  K,  the 
box  consisting  of  two  pieces  ;  h,  vertical  tube,  with  scale 
attached. 


Fig.  44. 

Sphygmometer  of 
H^risson  and 
Chelius. 


(2.)  H6rissou's  Tubular  Sphygmometer  consisted  of  a  glass-tube  whose 

lower  end  was  covered  with  an  elastic  membrane  (Fig.  44).  The  tube  was  partly 
filled  with  Hg.  The  membrane  was  placed  over  the  position  of  a  pulsating  artery, 
so  that  its  beat  caused  a  movement  in  the  Hg.     Chelius  used  a  similar  instrument, 


marey's  sphygmograph.  129 

and  he  succeeded  with  this  instrument  in  showing  the  existence  of  the  double- 
beat  (dicrotisra)  in  the  normal  pulse  (1850). 

(3.)  Vierordt's  Sphygmograph  (1855).— In  this,  one  of  the  earliest  sphygmo- 
graphs,  Vierordt  departed  from  the  principle  of  a  fluctuating  fluid  column,  and 
adopted  the  principle  of  the  ler^er.  Upon  the  artery  rested  a  small  pad,  which 
moved  a  complicated  system  of  levers.  At  first  he  used  a  straw  six  inches  long, 
which  rested  on  the  artery.  The  point  of  one  of  the  levers  inscribed  its  movements 
upon  a  revolving  cylinder.     This  instrument  was  soon  discarded. 

(4.)  Marey's  Sphygmograph  consists  of  a  combination  of  a  lever 
with  an  elastic  spring.  It  consists  of  an  elastic  spring  (Fig.  45,  A) 
fixed  at  one  end,  z,  free  at  the  other  end,  and  provided  with  an  ivory 
pad,  y,  which  is  pressed  by  the  spring  upon  the  radial  artery.  On 
the  upper  surface  of  the  pad  there  is  a  vertically-placed  fine  toothed 
rod,  h,  which  is  pressed  upon  by  a  weak  spring,  e,  so  that  its  teeth 
dove-tail  with  similar  teeth  in  the  small  wheel,  t,  from  whose  axis 
there  projects  a  long,  light,  wooden  lever,  v,  running  nearly  parallel 
with  the  elastic  spring.  This  lever  has  a  fine  style  at  its  free-end,  s, 
which  writes  upon  a  smoked  plate,  P,  moved  by  clock-work,  U,  in  front 
of  the  style.  Marey's  instrument,  as  improved  by  Mahomed  and  others, 
has  been  very  largely  used. 


Fig.  45. 

Scheme  of  Marey's  sphygmograph— A,  spring  with  ivory  pad,  y,  which  rests  on 
the  artery ;  e,  weak  spring  pressing  k  into  t ;  v,  wi'iting  lever ;  P,  piece  of 
smoked  glass  or  paper  moved  by  clock-work,  U  ;  H,  screw  to  limit  excursion 
of  A  ;  s,  arrangement  for  fixing  the  instrument  to  the  arm  of  the  patient. 

[Its  more  complete  form,  as  in  Fig.  46,  where  it  is  shown  applied  to  the  arm, 
consists  of — (1.)  a  steel  spring,  A,  which  is  provided  with  a  pad  resting  on  the 
artery,  and  moves  with  each  movement  of  the  artery  ;  (2. )  the  lever,  C,  which 
records  the  movement  of  the  artery  and  spring  in  a  magnified  form  on  the  smoked 
paper,  G  ;  (3.)  an  arrangement,  L,  whereby  the  exact  pressure  exerted  upon  the 
artery  is  indicated  on  the  dial,  M  (Mahomed)  ;  (4.)  the  clock-work,  H,  which 
moves  the  smoked  paper,  G,  at  a  uniform  rate ;  (5.)  a  frame-work  to  which  the 
various  parts  of  the  instrument  are  attached,  and  by  means  of  which  the  instru- 
ment is  fastened  to  the  arm  by  the  straps,  K,  K  (Byrom  Bramwell). 

[Application. — In  applying  the  sphygmograph,  cause  the  patient  to  seat  himself 
beside  a  low  table,  and  place  his  arm  on  the  double- inclined  plane  (Fig.  46).  In 
the  newer  form  of  instrument,  the  lid  of  the  box  is  so  arranged  as  to  unfold  to 
make  this  support.  The  fingers  ought  to  be  semi-flexed.  Mark  the  position  of 
the  radial  artery  with  ink.     See  that  the  clock-work  is  wound  up,  and  apply  the 

9 


130 


marey's  sphygmograph. 


ivory  pad  exactly  over  the  radial  artery  where  it  lies  upon  the  radius,  fixing  it  to 
the  arm  by  the  non -elastic  straps,  K,  K  (Fig.  46).  Fix  the  slide  holding  the  smoked 
paper  in  position.  The  best  paper  to  use  is  that  with  a  very  smooth  surface 
(album  inised  or  enamelled  card)  smoked  over  the  flame  of  a  turpentine  lamp,  or 
over  a  piece  of  burning  camphor.  The  writing-style  is  so  arranged  as  to  write 
upon  the  smoked  paper  with  the  least  possible  friction.    The  most  important  part 


Marey's  improved  sphygmograph  as  used  when  a  tracing  is  taken — A,  steel 
spring ;  B,  first  lever  j  C,  writing  lever ;  C,  its  free  writing  end ;  D,  screw 
for  bringing  B  in  contact  with  C ;  G,  slide  with  smoked  paper ;  H,  clock- 
work ;  L,  screw  for  increasing  the  pressure  ;  M,  dial  indicating  the  amount  of 
pressure ;  K,  K,  straps  for  fixing  the  instrument  to  the  arm,  and  the  arm  to 
the  double-inclined  plane  or  support  (Byrom  Bramwell). 

of  the  process  is  to  regulate  the  pressure  exerted  upon  the  artery  by  means  of  the 
milled  head,  L.  This  must  be  determined  for  each  pulse,  but  the  rule  is  to 
graduate  the  pressure  until  the  greatest  amplitude  of  movement  of  the  lever  is 
obtained.  Set  the  clock-work  going,  and  a  tracing  is  obtained,  which  must  be 
"  fixed  "  by  dipping  it  in  a  rapidly  drying  varnish — e.g.,  photographic.  In  every 
case  scratch  on  the  tracing  with  a  needle  the  name,  date,  and  amount  of  pressure 
employed.] 


Fig.  47. 


Fig.  48. 


[Fig.  47. — Scheme  showing  the' essential  part  of  the  instrument  when  inioork'mg 
order— i.e.,  the  turned  up  knife-edge,  B",  of  the  short  lever  in  contact  with 
the  writing  lever,  C.  Every  movement  of  the  steel  spring  at  A" — i.e.,  the 
artery — will  in  this  position  be  communicated  to  the  writing  lever. 

[Fig.  48. — Scheme  showing  the  essential  parts  of  the  instrument  after  increase  of 
the  pressure.  The  knife-edge,  B",  is  no  longer  in  contact  with  the  writing 
lever,  and  the  movements  of  the  steel  spring,  A" — i.e.,  the  artery— are  no 
longer  communicated  to  it.  In  order  to  put  the  instrument  into  working 
order,  the  knife-edge,  B",  must  be  raised  to  the  position  indicated  by  the 
jotted  line?.     This  is  effected  by  means  of  the  screw,  D  (Byrom  Bramwell).] 


dudgeon's  sphygmooraph. 


131 


[(5.)  Dudgeon's  Sphygmograph. — This  is  a  most  convenient  form  of 
sphygmograph.     Fig.  49  shows  its  actual  size. 


Fig.  49. — Dudgeon's  sphygmograph. 


The  instrument  after  being  carefully  adjusted  upon  the  radial  artery 
is  kept  in  position  by  an  inelastic  strap.  The  pressure  of  the  spring 
is  regulated  by  the  eccentric  wheel  to  any  amount  from  1  to  5  ounces. 


Pig.  50. — Mode  of  applying  Dudgeon's  sphygmograph. 


132 


brondgeest's  pansphygmograph. 


As  in  other  instruments,  the  tracing  paper  is  moved  in  front  of  the 
writing-needle  by  means  of  clock-work.  The  writing-levers  are  so 
adjusted  that  the  movements  of  the  artery  are  magnified  fifty  times.] 


Fig.  51.— Sphygmogram— pressure  2  oz. 


[Fig.  51  is  a  sphygmogram  taken 
with  this  instrument  from  a 
healthy  individual.  It  represents 
a  perfect  tracing — a,  the  vertical 
upward,  systolic  or  percussion 
wave;  h,  apex;  c,  on  the 
descent ;  d,  first  tidal  or  pre- 
dicrotic  wave ;  e,  aortic  notch  ; 
/,  dicrotic  wave  (Dudgeon).] 


(6.)  Marey's  Tambours  are  also  employed  for  registering  the  move- 
ments of  the  pulse.  They  are  used  in  the  same  way  as  thepansphygmograph 
of  Brondgeest,  Fig.  52  shows  their  arrangement.  Two  pairs  of  metaUic 
cups  (S,  S  and  S',  S',  Upham's  capsules)  are  pierced  in  the  middle  by 


Fig.  52. 

Scheme  of  Brondgeest's  sphygmograph,  on  the  principle  of  Upham  and  Marey's 
tambours-S,  S',  receiving  and  recording  (S,  S')  tambours  with  writing-levers, 
Z  and  Z';  K,  K',  conducting  tubes  :  p  over  heart,  p'  over  a  distant  artery. 
This  illustration  also  shows  the  principle  of  Marey's  cardiograph. 

thin  metal  tubes,  whose  free-ends  are  connected  with  caoutchouc  tubes, 
K  and  K'.  All  the  four  metallic  vessels  are  covered  with  an  elastic 
membrane.  On  S  and  S'  are  fixed  two  knob-like  pads,  p  and  /, 
which  are  applied  to  the  pulsating  arteries,  and  the  metal  arcs,  B  and 


LANDOIS    ANGIOGRAPH, 


133 


B',  retain  them  in  position.  On  the  other  tambours  are  arranged  the 
writing  levers,  Z  and  71.  Pressure  on  the  one  tambour  necessarily 
compresses  the  air  and  makes  the  other,  with  which  it  is  connected, 
expand,  so  as  to  move  the  writing-lever.  This  arrangement  does  not 
give  absolutely  exact  results ;  still,  it  is  very  easily  used  and  is  con- 
venient. In  Fig.  52  a  double 
arrangement  is  shown,  where- 
by one  instrument,  B,  may 
be  placed  over  the  heart,  and 
the  other,  B',  on  a  distant 
artery. 

Landois'  Angiograph. — To 
a  basal  plate,  G,  G,  are  fixed 
two  upright  supports,  ^,  which 
carry  between  them  at  their 
upper  part  the  movable  lever, 
d,  r,  carrying  a  rod  bearing  a 
pad,  e,  directed  downwards, 
which  rests  on  the  pulse. 
The  short  arm  carries  a  coun- 
terpoise, d,  so  as  exactly  to 
balance  the  long  arm.  The 
long  arm  has  fixed  to  it  at  r 
a  vertical  rod  provided  with 
teeth,  h,  which  is  pressed 
against  a  toothed  wheel  firmly 
fixed  on  the  axis  of  the  very 
light  writing-lever,  e  f,  which 
is  supported  between  two  up- 
rights, q,  fixed  to  the  opposite 
end  of  the  basal  plate,  G,  G. 
The  writing-lever  is  equilibri- 
ated  by  means  of  a  light 
weight.  The  writing-needle, 
k,  is  fixed  by  a  joint  to  e,  and 
it  writes  on  the  plate,  t.  The 
first  -  mentioned  lever,  d,  r, 
carries  a  shallow  plate,  Q,  just 
above  the  pad,  into  which 
weights  may  be  put  to  weight 
the  pulse.  In  this  instrument 
the  weight  can  be  measured 
and  varied  J  the  writing-lever  moves  vertically  and  not  in  a  curve, 


134 


CHARACTERS  0^  A   PULSE-CURVE. 


as  in  Marey's  apparatus,  which  greatly  facilitates   the  measuring  of 
the  curves.     (Fig.  53.) 

Other  sphygmographs  are  used,  both  in  this  country  and  abroad,  including  that 
of  Sommerbrodt,  which  is  a  complicated  form  of  Marey's  sphygmograph,  and 
those  of  Pond  and  Mach.  In  choosing  a  sphygmograph,  that  instrument  is  to  be 
preferred  which  yields  a  curve  corresponding  most  closely  with  the  variations  of 

the  pressure  within  the  artery,  in 
which  the  resistance  of  the  instrument 
is  small,  which  gives  the  largest  curve, 
and  in  which  the  part  in  contact  with 
the  artery  is  not  greatly  displaced 
from  its  position  of  equilibrium 
(Mach). 

Characters  of  a  Pulse-Curve.— 

In  every  pulse-curve — Sphygmo- 
GRAM  or  Arteriogram — we  can 
distinguish  the  ascending  part 
(ascent)  of  the  curve,  the  apex, 
and  the  descending  part  (descent). 
Secondary  elevations  scarcely 
ever  occur  in  the  ascent,  which 
is  usually  represented  by  a 
straight  line,  while  they  occur 
constantly  in  the  descent.  Such 
elevations  occurring  in  the  de- 
scent are  called  catacrofic,  and 
those  in  the  ascent,  anacrotic 
(Landois).  When  the  recoil 
elevation  or  dicrotip  wave  occurs 
in  a  well-marked  form  in  the 
descent,  the  pulse  is  said  to  be 
dicrotic,  and  when  it  occurs  twice, 
tricrotic. 

Measuring  Pulse-Curves— K  the 

smoked  surface  on  which  the  tracing 
is  inscribed  is  moved  at  a  uniform 
rate  by  means  of  the  clock-work, 
then  the  height  and  length  of  the 
curve  are  measured  by  means  of  an 
ordinary  rule.  If  we  know  the  rate 
at  which  the  paper  was  moved,  then 
it  is  easy  to  calculate  the  duration  of 
any  event  in  the  curve.  For  exact 
observation  a  low-power  microscope 
with  a  micrometer  in  the  eye-piece 
should  be  used. 


Fig.  54. 

Pulse-curves  of  the  carotid,  radial,  and 
posterial  tibial  arteries  of  a  healthy 
student,  obtained  by  Landois'  angio- 
graph  writing  upon  a  plate  attached 
to  a  vibrating  tuning-fork.  Each 
double  vibration  corresponds  to 
0'01613  sec. 


For  the  method  of  smoking  the  paper  and  fixing  the  tracings  see  p.  130. 


LANDOIS'  GAS-SPHYGMOSCOPE. 


135 


It  is  very  convenient  to  write  the  curve  upon  a  plate  of  glass  fixed 
to  a  tuning-fork  kept  in  vibration.  Every  part  of  the  curve  shows 
little  elevations  (whose  rate  of  vibration  is  known  beforehand).  All 
that  is  required  is  to  count  the  number  of  vibrations  in  order  to 
ascertain  the  duration  of  any  part  of  the  curve. 

Fig.  54  was  taken  in  this  way  from  (A)  the  carotid,  (B)  the  radial, 
and  (C)  the  posterior  tibial  arteries  of  a  healthy  student.     The  results 


are  : — 


1-2, 
1-3, 
1-4, 
1—5, 


arotid. 

Eadial. 

Posterior 
Tibial 

7 

.         .         7 

8 

17 

16 

19 

23-5     . 

.       22-5     . 

28 

56 

.       39 

.      49 

This  method  has  also  been  used  for  the  registration  of  other  physiological 
processes — e.g.,  contraction  of  muscle. 

Landois'  Gas-SphygmOSCOpe. — A  superficially  placed  artery  communicates  its 
movements  to  the  overlying  skin,  and  also  to  any  freely  movable  body  in  contact 
with  the  skin.  In  this  instrument  (Fig.  55)  a  thin  layer  of  air  over  the  pulsating 
artery,  a,  is  enclosed  by  means  of  a  thin  piece  of  metal,  which  is  so  adjusted  that 
its  concave  side  forms  a  tunnel  of  air  over  the  artery.  The  narrow  space  between 
the  metallic  wall,  b,  and  the  skin,  a,  is  filled  with  ordinary  gas,  one  end  of  the 
metal  shield  being  connected  by  means  of  a  tube,  g,  with  the  gas-supply,  while  to 
the  other  end  there  is  attached  by  means  of  a  short  piece  of  caoutchouc,  x,  q,  a 
bent  glass-tube,  t,  with  a  very  small  aperture  which  acts  as  a  gas-burner.  The 
gas  is  allowed  to  flow  through  the  apparatus  at  a  low  pressure,  and  is  so  regulated 
that  the  flame,  v,  is  only  a  few  millimetres  in  height.  The  flame  rises  isochron- 
ously  with  every  pulse-beat,  and  the  dicrotic  beat  in  the  normal  pulse  is  quite 
observable. 


Fig.  55. 

Landois'  gas-sphygmoscope — a,  akin  over  artery ;  b,  metal  plate ;  p,  g,  gaa ; 
X,  q,  caoutchouc  tube  attaching  glass  gas-burner,  t  to  b. 

Czermak  photographed  a  beam  of  light  set  in  motion  by  the  movements  of  the 
pulse. 

Hsemaatography. — Expose  a  large  artery  of  an  animal,  and  divide  it  so  that 
the  stream  of  blood  issuing  from  it  strikes  against  a  piece  of  paper  drawn  in  front 


136 


THE  PULSE-CURVE. 


of  the  blood-stream.     A  curve  (Fig. 
P 


Fig.  56. 

HEemautographic  curve  of  the  pos- 
terior tibial  artery  of  a  large  dog 
— P,  primary  pulse  wave ;  R, 
dicrotic  or  recoil  wave ;  e,  e, 
elevations  due  to  elasticity. 


56)  is  obtained  which  corresponds  very  closely 
with  the  pulse-traciug  obtained  from  a  normal 
artery.  In  addition  to  the  primary  wave,  P, 
there  is  a  distinct  "  recoil-elevation,"  or 
dicrotic  wave,  R,  and  slight  vibrations,  e,  e, 
due  to  variations  in  the  elasticity  of  the 
arterial  wall.  The  interest  which  attaches  to 
a  curve  obtained  in  this  way  is,  that  it  shows 
the  movements  to  occur  in  the  blood  itself, 
and  these  movements  to  be  communicated 
as  waves  to  the  arterial  wall.  By  estimat- 
ing the  amount  of  blood  in  the  various  parts 
of  the  curve  we  obtain  a  knowledge  of  the 
amount  of  blood  discharged  by  the  divided 
artery  during  the  systole  and  diastole  (i.e., 
the  narrowing  and  dilatation)  of  the  artery — 
the  ratio  is  7  :  10.  Thus  in  the  unit  of  time, 
during  arterial  dilatation  rather  more  than 
twice  as  much  blood  flows  out  as  happens 
during  arterial  contraction. 

Microphone. — Fix  a  small  piece  of  wax 
over  the  radial  artery,  and  to  it  attach  a  very 
fine  vertical  wire  which  is  brought  into  con- 
tact with  the  charcoal  of  a  microphone  held 
over  the  artery.  The  primary  pulse  wave 
and  dicrotic  wave  are  distinctly  heard  in  a 
telephone  brought  into  connection  with  the 
microphone  (Landois).  All  these  methods 
are  well  suited  for  demonstrating  the  pulse, 
but  for  accuracy  resort  must  be  had  to  some 
form  of  recording  instrument. 


68.  The  Pulse-Curve  or  Sphygmogram. 


A  sphygmogram  consists  of  several  curves,  each  one  of  which  corre- 
sponds with  a  beat  of  the  heart.  Each  pulse-curve  consists  of  (1.)  the 
ascending  part  which  occurs  during  the  dilatation  (diastole)  of  the 
artery;  (2.)  the  apex,  (P  in  Fig.  58  and  b  in  Fig.  57);  (3.)  the  de- 
scending part,  corresponding  to  the  contraction  (systole)  of  the  artery. 
The  most  noticeable  peculiarity  of  the  pulse-curve  is  the  existence 
of  tico  completely  distinct  elevations  occurring  in  the  descent.  The  more 
distinct  of  the  two  occurs  as  a  well-marked  elevation  about  the 
middle  of  the  descent  (R  in  Fig.  58  and  /  in  Fig.  57);  it  is  called  the 
DICROTIC  WAVE,  or  with  reference  to  its  mode  of  origin,  the  "  recoil 
wave."  The  ascent,  also  called  up-stroke  or  percussion  stroke 
(Mahomed),  in  a  normal  sphygmogram,  is  nearly  vertical,  while  the 
apex  of  the  percussion  stroke  is  usually  pointed. 

[In  Fig,  57,  each  part  of  the  curve  between  the  base  of  one  up- 


ORIGIN   AND   CHARACTERS   OF  THE  DICROTIC   WAVE.  137 

stroke  and  the  base  of  the  next  up-stroke  corresponds  to  a  beat  of  the 

heart,  so  that  this  figure 

shows  five  heart-beats  and 

part  of  a  sixth.    The  part, 

a,  b  =  the   ascent,   b,  the 

apex  of  the  up-stroke,  and 

b  to  h,  the  descent,  with  a 

curve,  d,  called   the   first  ^.     ._ 

tidal  or  predicrotic  wave,         gphygmogram  of  radial  artery— pressure  2  oz. 
e,  an  angle  or  notch,  the 

aortic  notch,  /,  a  second  elevation,  called  the  dicrotic  wave,  g,  a  slight 
curve,  sometimes  called  the  second  tidal  wave.  The  descent  is  con- 
tinued to  h,  where  the  ascent  of  the  next  heart-beat  begins,] 

I.  Origin  and  Characters  of  the  Dicrotic  Wave. 

The  dicrotic  or  recoil  wave,  which  is  always  present  in  a  normal 
pulse,  is  caused  thus  : — During  the  ventricular  systole  a  mass  of  blood 
is  propelled  into  the  already  full  aorta,  whereby  a  positive  wave  is 
rapidly  transmitted  from  the  aorta  throughout  the  arterial  system,  even 
to  the  smallest  arterioles,  in  vjJiich  this  primary  wav.  is  extinguished.  As 
soon  as  the  semi-lunar  valves  are  closed,  and  no  more  blood  flows  into 
the  arterial  system,  the  arteries  which  were  previously  distended  by  the 
mass  of  blood  suddenly  thrown  into  them,  recoil  or  contract,  so  that 
in  virtue  of  the  elasticity  (and  contractility)  of  their  walls,  they 
exert  a  counter-pressure  upon  the  column  of  blood,  and  thus  the  blood 
is  forced  onwards.  There  is  a  free  passage  for  it  towards  the  periphery, 
but  towards  the  centre  (heart)  it  impinges  upon  the  already  closed 
semi-lunar  valves.  This  developes  a  new  positive  wave,  which  is  pro- 
pagated peripherally  through  the  arteries,  where  it  disappears  in  their 
finest  branches.  In  those  cases  where  there  is  sufficient  time  for  the 
complete  development  of  the  pulse-curve  (as  in  the  short  course  of  the 
carotids,  and  in  the  arteries  of  the  upper  arm,  but  not  in  those  of  the 
lower  extremity,  on  account  of  their  length),  a  second  wave  of  reflec- 
tion may  be  caused  in  exactly  the  same  way  as  the  first. 

Just  as  the  pulse  occurs  later  in  the  more  peripherally  placed 
arteries  than  in  those  near  the  heart,  so  the  secondary  wave  reflected 
from  the  closed  aortic  valves  must  appear  later  in  the  peripheral 
arteries.  Both  kinds  of  waves,  the  primary  pulse  wave,  the  secondary, 
and  eventually  even  the  tertiary  reflected  wave  arise  in  the  same  place, 
and  take  the  same  course,  and  the  longer  the  course  they  have  to 
travel  to  any  part  of  the  arterial  system,  the  later  they  arrive  at  their 
destination. 


1S8 


CHARACTERS  OF  THE  DICROTIC  WAVE. 


The  following  points  regarding  the  dicrotic  wave  have  been  ascer- 
tained experimentally ; — 


IV 


I,  II,  III,  Si>hygmogram  of  carotid  artery;  IV,  axillary;  V  to  IX,  radial; 
X,  dicrotic  radial  pulse;  XI,  XIT,  crural;  XIII,  posterior  tibial;  XIV, 
XV,  pedal.  In  all  the  curves— P,  indicates  apex ;  R,  dicrotic  wave ;  e,  e, 
elevations  due  to  elasticity;  K,  elevation  caused  by  closure  of  the  semi-lunar 
valves  of  the  aorta. 


(1.)  The  dicrotic  wave  occurs  later  in  the  descending  part  of  the 


ORIGIN  AND  CHARACTERISTICS  OF  THE  ELASTIC  ELEVATIONS.     139 

curve,  the  further  the  artery  experimented  upon  is  distant  from  the 
heart  (Landois,  1863).     Compare  the  curves,  Fig.  54,  p.  134. 

The  shortest  accessible  course  is  that  of  the  carotid  :  where  the  dicrotic  wave 
reaches  its  maximum  035  to  037  sec.  after  the  beginning  of  the  pulse.  In  the 
upper  extremity  the  apex  of  the  dicrotic  wave  is  0'36  to  0*38  to  0*40  sec.  after 
the  beginning  of  the  pulse-beat.  The  longest  course  is  that  of  the  arteries  of  the 
lower  extremity.  The  apex  of  the  dicrotic  wave  occurs  0'45  to  0  52  to  0"59  sec. 
after  the  base  of  the  cur\'e.     It  varies  mth  the  height  of  the  individual. 

(2.)  The  dicrotic  elevation  in  the  descent  is  lower  (Naumann),  and 
is  less  distinct  (Landois),  the  further  the  artery  is  situated  from  the 
heart.  This  is  just  what  one  would  expect — viz.,  the  longer  the 
distance  which  the  wave  has  to  travel  the  less  distinct  it  must  become. 

(3).  It  is  more  pronounced  in  a  pulse  where  the  primary  pulse- wave 
is  short  and  energetic  (Marey,  Landois).  It  is  greatest  relatively 
when  the  systole  of  the  heart  is  short  and  energetic. 

(4.)  It  is  greater  the  lower  the  tension  or  pressure  of  the  blood 
within  the  arteries  (Marey,  Landois),  [and  is  best  developed  in  a  soft 
pulse].  In  Fig.  58,  IX  and  X  were  obtained  when  the  tension  of  the 
arterial  wall  was  Imv;  V  and  VI,  medium;  and  VII  with  high  tension. 

Conditions  Influencing  Arterial  Tension.— It  is  diminished  &t  the  beginning 

of  inspiration,  by  haemorrhage,  stoppage  of  the  heart,  heat,  an  elevated  position  of 
parts  of  the  body ;  it  is  increased  at  the  beginning  of  expiration  by  accelerated 
action  of  the  heart,  stimulation  of  vaso-motor  nerves,  diminished  outflow  of  blood 
at  the  periphery,  and  by  inflammatory  congestion  (Knecht) ;  further,  by  certain 
poisons,  as  lead,  amyl  nitrite  ;  compression  of  other  large  arterial  trunks,  action  of 
cold  and  electricity  on  the  small  cutaneous  vessels,  and  by  impeded  outflow  of  venous 
blood.  When  a  large  arterial  trunk  is  exposed  the  stimulation  of  the  air  causes 
it  to  contract,  resulting  in  an  increased  tension  within  the  vessel.  In  many 
diseased  conditions  the  arterial  tension  is  greatly  increased — {e.g.,  in  Bright'a 
disease,  where  the  kidney  is  contracted  ("granular"),  and  where  the  left  ventricle 
is  hypertrophied]. 

In  all  these  conditions  increased  arterial  tension  is  indicated  by  the  dicrotic 
wave  being  less  high  and  less  distinct,  while  with  diminished  arterial  tension  it  is 
a  larger  and  apparently  more  independent  elevation.  Moens  has  shown  that  the 
time  between  the  primary  elevation  and  the  dicrotic  wave  increases  with  increase 
in  the  diameter  of  the  tube,  with  diminution  of  its  thickness,  and  when  its 
coefficient  of  elasticity  diminishes. 

II.  Origin  and  Characteristics  of  the  Elastic 
Elevations. 

Besides  the  dicrotic  wave,  a  number  of  small  less-marked  elevations 
occur  in  the  course  of  the  descent  in  a  sphygmogram  (Fig.  58,  e,  e). 
These  elevations  are  caused  by  the  elastic  tube  being  thrown  into 
vibrations  by  the  rapid  energetic  pulse- wave,  just  as  an  elastic  mem- 
brane vibrates  when  it  is  suddenly  stretched.     The  artery  also  executes 


140  DICROTIC  PULSi:. 

vibratory  movements  "when  it  passes  suddenly  from  the  distended  to 
the  relaxed  condition.  These  small  elevations  in  the  pulse-curve, 
caused  by  the  elastic  vibrations  of  the  arterial  wall,  are  called  "  elastic 
elevations  "  by  Landois. 

(1.)  The  elastic  vibrations  increase  in  number  in  one  and  the  same 
artery  with  the  degree  of  tension  of  the  elastic  arterial  wall.  A  very 
high  tension  occurs  in  the  cold  stage  of  intermittent  fever,  in  which 
case  these  elevations  are  well  marked.  (2.)  If  the  tension  of  the 
arterial  wall  be  greatly  diminished  these  elevations  may  disappear, 
so  that  while  diminished  tension  favours  the  production  of  the  dicrotic 
wave,  it  acts  in  the  opposite  way  with  reference  to  the  "  elastic 
elevations."  (3.)  In  diseases  of  the  arterial  walls  affecting  their 
elasticity,  these  elevations  are  either  greatly  diminished  or  entirely 
abolished.  (4.)  The  farther  the  arteries  are  distant  from  the  heart, 
the  higher  are  their  elevations.  (5.)  When  the  mean  pressure  within 
the  arteries  is  increased  by  preventing  the  outflow  of  blood  from 
them,  the  elastic  vibrations  are  higher  and  nearer  the  apex  of  the 
curve.  (6.)  They  vary  in  number  and  length  in  the  pulse-curves 
obtained  from  different  arteries  of  the  body. 

When  the  arm  is  held  in  an  upright  position,  after  five  minutes  the  blood-vessels 
empty  themselves,  and  collapse,  while  the  elasticity  of  the  arteries  is  diminished. 

69.  Dicrotic  Pulse. 

Sometimes  during  fever,'especially  when  the  temperature  is  high,  a  dicrotic  pulse 
may  be  felt,  each  pulse-beat,  as  it  were,  being  composed  of  two  beats  (Fig.  58,  X), 


Fig.  59. 
Pulsus  dicrotus— P.  caprizans ;  P.  monocrotus. ' 

one  beat  being  large  and  the  other  small,  and  more  like  an  after-beat.  Both 
beata  correspond  to  07ie  beat  of  the  heart.  The  two  beats  are  quite  distinguishable 
by  the  touch.    The  phenomenon  is  only  an  exaggerated  condition  of  what  occurs 


CHARACTERS   OF  THE  PULSE.  141 

in  a  normal  pulse.  The  sensible  second  beat  is  nothiwj  more  than  the  greatly 
increased  dicrotic  elevation,  which,  under  ordinary  conditions,  is  not  felt  by  the 
finger. 

Conditions. — The  occurrence  of  a  dicrotic  pulse  is  favoured  (1)  by  a  short 
primary  pulse-wave,  as  in  fevers,  where  the  heart  beats  rapidly ;  (2)  by  a 
diminished  tension  within  the  arterial  system.  A  short  systole  and  diminished 
arterial  blood-pressure  are  the  most  favourable  conditions  for  causing  a  dicrotic 
pulse.  The  double-beat  may  be  felt  only  at  certain  parts  of  the  arterial  system, 
whilst  at  other  parts  only  a  single  beat  is  felt.  A  favourite  site  is  the  radial 
artery  of  one  or  the  other  side,  where  conditions  favourable  to  its  occurrence  appear 
to  exist.  This  seems  to  be  due  to  a  local  diminution  of  the  blood-pressure  in  this 
area,  owing  to  the  paralysis  of  its  vaso-motor  nerves  (Landois).  If  the  tension  be 
increased  by  compressing  other  large  arterial  trunks  or  the  veins  of  the  part,  the 
double-beat  becomes  a  simple  pulse-beat.  The  dicrotic  pulse  in  fever  seems  to  be 
due  to  the  increased  temperature  (39°  to  40°C.),  whereby  the  artery  is  more  dis- 
tended, and  the  heart-beat  is  shorter  and  more  prompt  (Riegel). 

(3.)  It  is  absolutely  necessary  that  the  elasticity  of  the  arterial  loall  he  normal. 
The  dicrotic  pulse  does  not  occur  in  old  persons  with  atheromatous  arteries 
(Landois).  In  Fig.  59,  A,  B,  C,  we  observe  the  gradual  passage  of  the  normal 
radial  curve,  A,  into  the  dicrotic  beat,  B,  C,  where  the  dicrotic  wave,  r,  appears 
as  an  independent  elevation.  If  the  frequency  of  the  pulse  increases  more  and 
more  in  fever,  the  next  following  pulse-beat  may  occur  in  the  ascending  part  of 
the  dicrotic  wave,  D,  E,  F,  and  it  may  even  occur  close  to  the  apex,  G  (P. 
caprizans).  If  the  next  following  beat  occurs  in  the  depression,  i,  between  the 
primary  elevation,  p,  and  the  dicrotic  elevation,  r,  the  latter  entirely  dis- 
appears, and  the  curves,  H,  assume  what  Landois  calls  the  "  monocrotic  "  type. 


70.  Characters  of  the  Pulse. 

1.  Pulsus  Frequens  and  Rarus. 

Frequency. — According  as  a  greater  or  less  number  of  beats  occurs  in  a  given 
time,  e.g.,  per  minute,  the  pulse  is  said  to  be  frequent  or  rare.  The  normal 
rate,  in  man=71  per  minute,  and  somewhat  more  in  the  female  ;  in  fever  it  may 
exceed  120  (250  have  been  counted  by  Bowles),  while  in  other  diseases  it  may  fall 
to  40,  and  even  10  to  15  (de  Haen),  17  (Hartog),  and  14  (Cornil) ;  but  such 
cases  are  rare,  and  are  probably  due  to  an  affection  of  the  cardiac  nerves.  The 
frequency  of  the  pulse  is  usually  increased  when  the  respirations  are  deeper,  but 
not  more  numerous,  i.e.,  rapid  shallow  respirations  do  not  affect  the  frequency  of 
the  pulse,  but  deep  respirations  do  (Knoll). 

2,  Pulsus  Celer  and  Tardus. 

Celerity  or  Rapidity.— If  the  pulse-wave  is  developed  so  that  the  distension  of 
the  artery  slowly  reaches  its  height  and  the  relaxation  also  takes  place  gi'adually, 
we  have  the  p.  tardus  or  slow  pulse,  the  opposite  condition  gives  rise  to  the  p. 
celer  or  quich  pulse.  The  rapidity  of  the  pulse  is  increased  by  quick  action  of  the 
heart,  power  of  expansion  of  the  arterial  walls,  easy  efflux  of  blood  owing  to  the 
dilatation  of  the  small  arteries,  and  by  nearness  to  the  heart.  [The  quichiess 
has  reference  to  a  single  pulse-beat,  the  frequency  to  a  number  of  beats.]  In  a 
quick  pulse,  the  curve  is  high  and  the  angle  at  the  apex  is  acute,  while  in  a  slow 
pulse  the  ascent  is  low  and  the  angle  at  the  apex  is  large. 


142 


CONDITIONS  AFFECTING   THE  PULSE-RATE. 


3.    Conditions  affecting  the  Fnlse-Rate. 

Fteqnency  in  Health- — In  man  the  normal  pulse-rate =71  to  72  beats  per 
minute,  in  the  female  about  80.  In  some  individuals  the  pulse-rate  may  be  higher 
(90  to  100),  in  others  lower  (50),  and  such  a  fact  must  be  borne  in  miad.  The 
following  conditions  influence  it — 

(a.)  Age. 


Beats  per 
Minute. 

130  to  140 

10  to  15  Years 

120  to  130 

15  to  20      ,, 

105 

20  to  25      „ 

100 

25  to  50      „ 

97 

60 

94  to    90 

80 

about  90 

80  to  90      ,, 

Newly  Born, 

1  Year, 

2  Years, 

3  „ 

4  „ 

5  „ 
10      „ 

(b.)  The  length  of  the  body  has  a  certain  relation  to  the  frequency  of  the 
pulse.  The  following  results  have  been  obtained  by  Czarnecki  from  the  formulae 
of  Volkmann  and  Rameaux — 


Beats  per 
Minute. 

78 
70 
70 
70 
74 
79 
over  80 


Length  of  Body 
in  10  Ctm. 

Pulse 
Calculated.  Observed. 

Length  of  Body                                  Pulse, 
in  10  Ctm.                       Calculated.  Observed 

80  to  90      . 

.      90 

103 

140  to  150  . 

69            74 

90  to  100     . 

.      86 

91 

150  to  160  . 

67            68 

100  to  110     . 

.      81 

87 

160  to  170  . 

65            65 

110  to  120     . 

.      78 

84 

170  to  180. 

63            64 

120  to  130     . 

.      75 

78 

above  180  . 

60            60 

130  to  140     . 

.      72 

76 

(c.)  The  pulse-rate  is  increased  by  muscular  activity,  by  every  increase  of  the  arterial 
blood-pressure,  by  talcing  of  food,  increased  temperature,  -painful  sensations,  and  by 
psychical  disturbances.  [Increased  heat  or  fever  (Pyrexia)  increases  the  frequency, 
and  as  a  rule  the  increase  varies  with  the  height  of  the  temperature.  Dr.  Aitken 
states  that  an  increase  of  the  temperature  of  1°  F.  above  98°  F.  corresponds  with  an 
increase  of  ten  pulse-beats  per  minute ;  thus, 

Pulse-Bate. 
.       110 
.       120 
.       130 
.         .       140 


This  is  merely  an  approximate  estimate.]  It  is  more  frequent  when  a  person  is 
standing  than  when  he  lies  down.  Music  accelerates  the  pulse  and  increases  the 
blood-pressure  in  dogs  and  men  (Dogiel).  Exposure  to  increased  barometric 
pressure  diminishes  the  frequency. 

The  variation  of  the  pulse-rate  during  the  day — 3  to  6  a.m.  =61  beats  ;  8  to  114 
a.m.  =74.  It  then  falls  towards  2  p.m.  ;  towards  3  (at  dinner-time)  another 
increase  takes  place  and  goes  on  until  6  to  8  p.m.,  =70 ;  and  it  falls  until  mid- 
night =54.  It  then  rises  again  towards  2  a.m.,  when  it  soon  falls  again,  and 
afterwards  rises  aa  before  towards  3  to  6  a.m. 


Temp.  F. 

Pulse-Kate. 

Temp.  F. 

98°    . 

60 

103° 

99°    . 

70 

104° 

100°  . 

80 

105° 

101°  . 

90 

106° 

102°   . 

.       100 

4.    Variations  in  the  Pulse-Rhythm. 

On  applying  the  fingers  to  the  normal  pulse  we  feel  beat  after  beat  occurring 
at  apparently  equal  intervals.  Sometimes  in  a  normal  series  a  beat  is  omitted 
s=  pulsus  intermittens,  or  intermittent  pulse ;   at  other  times  the  beats  become 


VARIATIONS  IN  THE  STRENGTH, TENSION,  AND  VOLUME  OF  THE  PULSE.  143 

smaller  and  smaller,  and  after  a  certaiii  time  begin  as  large  as  before  =  P.  my  urns. 
When  an  extra  beat  is  intercalated  iu  a  normal  series  =  P.  iniercurrens.  The 
regular  alternation  of  a  high  and  a  low  beat  =  P.  alternans  (Traube).  In  the 
P.  bigeyninus  of  Traube  the  beats  occur  in  pairs,  so  that  there  is  a  longer  pause 


Fig.  60, 
Pulsus  alternans. 

after  every  two  beats.  Traube  found  that  he  could  produce  this  form  of  pulse  in 
curarised  dogs  by  stopping  the  artificial  respiration  for  a  long  time.  The  P.  trige- 
viinua  and  quadrigcminus  occur  in  the  same  way,  but  the  irregularities  occur  after 
every  third  and  fourth  beat.  Knoll  found  that  in  animals  such  irregularities  of 
the  pulse  were  apt  to  occur,  as  well  as  great  irregularity  in  the  rhythm  generally, 
when  there  is  great  resistance  to  the  circulation,  and  consequently  the  heart  has  great 
demands  upon  its  energy.  The  same  occurs  in  man,  when  an  improper  relation 
exists  between  the  force  of  the  cardiac  muscle  and  the  work  it  has  to  do  (Riegel). 
Complete  irregularity  of  the  heart's  action  is  called  arhythmia  cordis. 

71.  Variations  in  the  Strength,  Tension,  and 
Volume  of  the  Pulse. 

The  relative  strength  of  the  pulse  (p.  fortis  and  debilis),  i.e.,  whether  the  pulse 
is  strong  or  7veaJc,  is  estimated  by  the  weight  which  the  pulse  is  able  to  raise.  A 
sphygmograph,  provided  with  an  index  indicating  the  amount  of  pressure  exerted 
upon  the  spring  pressing  upon  the  artery,  may  be  used  (Fig.  46).  In  this  case, 
as  soon  as  the  pressure  exerted  upon  the  artery  overcomes  the  pulse-beat,  the 
lever  ceases  to  move.  The  weight  employed  indicates  the  strength  of  the  jyuUe. 
[The  finger  may  be,  and  generally  is,  used.  The  finger  is  pressed  upon  the 
artery  until  the  pulse-beat  in  the  artery  beyond  the  point  of  pressure  is  obliterated. 
In  health  it  requires  a  pressure  of  several  ounces  to  do  this.  Handfield  Jones  uses 
a  SPHYGMOMETER  for  this  purpose.  It  is  constructed  like  a  cylindrical  letter- 
weight,  and  the  pressure  is  exerted  by  means  of  a  spiral  spring  which  has  been 
carefully  graduated.]  The  pulse  is  hard  or  soft  when  the  artery,  according  to  the 
mean  blood  pressure,  gives  a  feeling  of  greater  or  less  resistance  to  the  finger,  and 
this  quite  independent  of  the  energy  of  the  individual  pulse-beats  (P.  durus  and 
mollis). 

In  estimating  the  tension  of  the  artery  and  the  pulse,  i.e.,  whether  it  is  hard 
or  soft,  it  is  important  to  observe  whether  the  artery  has  this  quality  only  during 
the  pulse- wave,  i.e.,  if  it  is  hard  during  diastole,  or  whether  it  is  hard  or  soft 
during  the  period  of  rest  of  the  arterial  wall.  All  arteries  are  harder  and  less 
compressible  during  the  pulse-beat  than  during  the  period  of  rest,  but  an  artery 
which  is  very  hard  during  the  pulse-beat  may  be  hard  also  during  the  pause 


144  THE  PULSE-CURVES   OF  VARIOUS  ARTERIES. 

between  the  pulse-beats,  or  it  may  be  very  soft,  as  in  insufficiency  of  the  aortic 
valves.  In  this  case,  after  the  systole  of  the  left  ventricle,  owing  to  the  incom- 
petency of  the  semi-lunar  valves,  a  large  amount  of  blood  flows  back  into  the 
ventricle,  so  that  the  arteries  are  thereby  suddenly  rendered  partially  empty.  [The 
sudden  collapse  of  the  artery  gives  rise  to  the  characteristic  "pulse  of  unfilled 
arteries. "] 

Under  similar  conditions,  the  volume  of  the  pulse  is  obvious  from  the  size  of 
the  sphygmogram,  so  that  we  speak  of  a  large  and  a  small  pulse  (P.  magnus  and 
parvus).  Sometimes  the  pulse  is  so  thready  and  of  such  diminished  volume  that 
it  can  scarcely  be  felt.  A  large  pulse  occurs  in  disease  when,  owing  to  hyper- 
trophy of  the  left  ventricle,  a  large  amount  of  blood  is  forced  into  the  aorta.  A 
small  pulse  occurs  under  the  opposite  condition,  when  a  small  amount  of  blood  is 
forced  into  the  aorta,  either  from  a  diminution  of  the  total  amount  of  the  blood, 
or  from  the  aortic  orifice  being  narrowed,  or  from  disease  of  the  mitral  valve ;  again, 
where  the  ventricle  contracts  feebly,  the  pulse  becomes  small  and  thready. 
Sometimes  the  pulse  differs  on  the  two  sides,  or  it  may  be  absent  on  one  side. 

Waldenburg  constructed  a  "pulse-clock  "  to  register  the  tension,  the  diameter 
of  the  artery,  and  the  volume  of  the  pulse  upon  a  dial.  It  does  not  give  a  graphic 
tracing,  the  results  being  marked  by  the  position  of  an  indicator. 

72.  The  Pulse-Curves  of  Various  Arteries. 

1.   Carotid  (Fig.  54,  A,;    Fig.  58, 1,  II,  III ;     Fig.  64,  0  and  C^). 

The  ascending  part  is  very  steep — ^the  apex  of  the  curve  (Fig.  58,  P) 
is  sharp  and  high.  Below  the  apex  there  is  a  small  notch — the 
"aortic  notch"  (Fig.  58,  K) — which  depends  on  a  positive  wave 
formed  in  the  root  of  the  aorta,  owing  to  the  closure  of  the  aortic 
valves,  and  propagated  with  almost  wholly  undiminished  energy 
into  the  carotid  artery.  Quite  close  to  this  notch,  if  the  curve  be 
obtained  with  minimal  friction,  the  first  elastic  vibration  occurs  (Fig. 
58,  II,  e).  Above  the  middle  of  the  descending  part  of  the  curve  is  the 
dicrotic  elevation,  R,  produced  by  the  reflection  of  a  positive  wave 
from  the  already  closed  semi-lunar  valves.  The  dicrotic  wave  is  rela- 
tively small  on  account  of  the  high  tension  in  the  carotid  artery. 
After  this  the  curve  falls  rapidly,  but  in  its  lowest  third  two  small 
elevations  may  be  seen.  Of  these  the  former  is  due  to  elastic  vibration. 
The  latter  represents  a  second  dicrotic  wave — (Fig.  58,  III,  R),  (Landois, 
Moens).  Here  there  is  a  true  tricrotism,  which  is  more  easily  obtained 
from  the  carotid  on  account  of  the  shortness  of  the  arterial  channel. 

Moens  describes  the  "aortic  elevation"  as  occurring  at  the  moment  of  the 
closure  of  the  aortic  valves. 

2.    Axillary  Artery  (Fig.  58,  IV). 

In  this  curve  the  ascent  is  very  steep,  while  in  the  descent  near  the 
apex  there  is  a  small  (aortic)  elevation,  K,  caused  by  a  positive  wave, 
produced  by  the  closure  of  the  aortic  valves.     Below  the  middle  there 


PULSE-CURVES  OF  VARIOUS  ARTERIES. 


145 


is  a  tolerably  high  dicrotic  elevation,  R,  higher  than  in  the  carotid 
curve;  because  in  the  axillary  artery  the  arterial  tension  is  less,  and 
permits  a  greater  development  of  the  dicrotic  wave.  Further  on,  two 
or  three  small  elastic  vibrations  occur,  e,  e. 

3.  Eadial  Artery  (Fig.  54,  B;  Fig.  58,  V-X;  Fig.  64,  R  and  Ri). 

The  line  of  ascent  (Fig.  58)  is  tolerably  high  and  sudden — some- 
what in  the  form  of  a  long/.  The  apex,  P,  is  well  marked.  Below 
this,  if  the  tension  be  high,  two  elastic  vibrations  may  occur  (V,  e,  e),  but 
if  it  be  low,  only  one  (VI  to  IX,  e).  About  the  middle  of  the  curve  is 
the  well-marked  dicrotic  elevation,  R, 

This  wave  is  least  pronounced  in  a  small  hard  pulse,  and  when  the 
artery  is  much  distended  (Fig.  58,  VII,  Rj);  it  is  larger  when  the 
tension  is  low  (Fig.  56,  IX,  R),  and  is  greatest  of  all  when  the 
pulse  is  dicrotic  (X,  R).  Two  or  three  small  elastic  elevations  occur 
in  the  lowest  part  of  the  curve. 

4.  Femoral  Artery  (Fig.  58,  XI,  XII). 

The  ascent  is  steep  and  high — the  apex  of  the  curve  is  not  unfre- 
quently  broad,  and  in  it  the  closure  of  the  aortic  valves  (K)  is 
indicated.  The  curve  falls  rapidly  towards  its  lower  third.  The 
dicrotic  elevation,  R,  occurs  late  after  the  beginning  of  the  curve,  and 
there  are  also  small  elastic  elevations  {e,  e). 

5.  Pedal  Artery  (Fig.  58,  XIV,  XV),  and  Posterior  Tibial 
(Fig.  54,  C,  and  Fig.  58,  XIII). 

In  pulse-curves  obtained  from  these  arteries,  there  are  well-marked 
indications  that  the  apparatus  (heart)  producing  the  waves  is  placed  at 


Fi^.  61. 

A,  curve  of  posterior  tibial,  and  B,  pedal  artery  of  a  mau.     Curves  written  by  the 
angiograph  upon  a  vibrating  plate  attached  to  a  tuning-fork. 

a  considerable  distance.     The  ascent  is  oblique  and  low — the  dicotric 
elevation  occurs  late.     Two  elastic  vibrations  (Fig.  58,  XIV,  e,  e)  occur 

10 


146  ANAOROTISM. 

in  the  descent,  but  they  occur  very  close  to  the  apex,  while  the  elastic 
vibrations  at  the  lower  part  of  the  curve  are  feebly  marked.  In 
Fig.  61,  A  is  from  the  posterior  tibial,  and  B  from  the  pedal  artery 
of  the  same    individual.     When  measured,  they  give  the  following 

result : — 

A  B    \ 

1—2 9-5  9  I  ,     M     .        • 

1     q  20  20  I  ^  vibration  is 

1-^ il^  Z  I  -001613  sec. 

1—4 30-5  32  I 

1—6 61  62-5  j 

73.  Anacrotism. 

As  a  general  rule,  the  line  of  ascent  of  a  pulse-curve  has  the  form  of  an  /,  and  is 
nearly  vertical.  The  arterial  walls  are  thrown  into  elastic  vibration  by  the  pulse- 
beat,  and  the  number  of  vibrations  depends  greatly  upon  the  tension  of  the  arterial 
walls. 

The  distension  of  the  artery,  or  what  is  the  same  thing,  the  ascent  of  the  sphyg- 
mogram,  usually  occurs  so  rapidly  that  it  is  equal  to  one  elastic  vibration.  The 
elongated /-shape  of  the  ascent  is  fundamentally  just  a  prolonged  elastic  vibration. 
When  the  number  of  vibrations  causing  the  elastic  variation  is  small,  and  when 
the  line  of  ascent  is  prolonged,  two  elevations  occasionally  occur  in  the  line  of 
ascent.  Such  a  condition  may  occur  normally  (Fig.  56,  VIII  at  1  and  2 ;  X  at  1 
and  2).  When  a  series  of  closely-placed  elastic  vibrations  occur  in  the  upper  part 
of  the  line  of  ascent,  so  that  the  apex  appears  dentate  and  forms  an  angle  with  the 
line  of  ascent,  then  the  condition  becomes  one  of  Anacrotlsm  (Fig.  62,  a,  a), 
•which,  when  it  becomes  so  marked,  may  be  characterised  as  pathological  (Landois). 
Anacrotism  of  the  pulse  occurs  when  the  time  of  the  influx  of  the  blood  is  longer 
than  the  time  occupied  by  an  elastic  vibration.     Hence  it  takes  place  : — 

(1.)  In  dilatation  and  hypertrophy  of  the  left  ventricle,  e.g.,  Fig.  62,  A,  a  tracing 
from  the  radial  artery  of  a  man  suffering  from  coatracted  kidney.  The  large 
volume  of  blood  expelled  with  each  systole  requires  a  long  time  to  dilate  the  tense 
arteries. 

(2.)  AVhen  the  extensibility  of  the  arterial  wall  is  diminished  even  the  normal 
amount  of  blood  expelled  from  the  heart  at  every  systole  requires  a  long  time  to 
dilate  the  artery.  This  occurs  in  old  people  where  the  arteries  tend  to  become 
rigid,  e.g.,  in  atheroma.  Cold  also  stimulates  the  arteries  so  that  they  become  less 
extensile.  Within  one  hour  after  a  tepid  bath,  the  pulse  assumes  the  anacrotic 
form  (Fig.  62,  D)— (G.  v.  Liebig.) 

(3.)  When  the  blood  stagnates  in  consequence  of  great  diminution  in  the  velocity 
of  the  blood-stream,  as  occurs  in  paralysed  limbs,  the  volume  of  blood  propelled 
into  the  artery  at  every  systole  no  longer  produces  the  normal  distension  of  the 
arterial  coats,  and  anacrotic  notches  occur  (Fig.  62,  B). 

(4.)  After  ligature  of  an  artery,  when  blood  slowly  reaches  the  peripheral  part 
of  the  vessel  through  a  relatively  small  collateral  circulation,  it  also  occurs.  If 
the  brachial  artery  be  compressed  so  that  blood  slowly  reaches  the  radial,  the 
radial  pulse  may  become  anacrotic.  It  often  occurs  in  stenosis  of  the  aorta,  as  the 
blood  has  difficulty  in  getting  into  the  aorta  (Fig.  62,  C). 

Recurrent  Pulse. — If  the  radial  artery  be  compressed  at  the  wrist, 
the  pulse-beat  reappears  on  the  distal  side  of  the  point  of  pressure 
through  the  arteries  of  the  palm  of  the  hand  (Janaud,  Neidert).     The 


ANACROTISM, 


147 


curve  is  anacrotic,  and  the  dicrotic  wave  is  diminished,  while  the  elastic 
elevations  are  increased. 


Anacrotic  pulse-curves — A,  B,  C,  D,  from  the  radial  artery ;  o,  a,   the   anacrotic 
notches;  I.,  II.,  III.,  curves  with  anacrotic  elevations— a  in  insulBciency  of 

the  aortic  valves. 

(5.)  A  special  form  of  anacrotism  occurs  in  cases  of  ivcU-inarJced  insvfficiency  of 
the  aortic  valves.  Practically,  in  these  cases,  the  aorta  remains  permanently  open. 
The  contraction  of  the  left  auricle  causes  in  the  blood  a  wave-motion,  which  is  at 
once  propagated  through  the  open  mouth  of  the  aorta  into  the  large  blood-vessels. 
This  wave  is  followed  by  the  wave  caused  by  the  contraction  of  the  hypertrophied 
left  ventricle,  but  of  course  the  former  wave  is  not  so  large  as  the  latter.  In 
insufficiency  of  the  aortic  valves,  the  auricular  wave  occurs  before  the  ventricular 
wave  in  the  ascending  part  of  the  curve.  The  auricular  is  weU  marked  only  in 
the  large  vessels,  for  it  soon  becomes  lost  in  the  peripheral  vessels.  Fig.  62, 1. ,  was 
obtained  from  the  carotid  of  a  man  suffering  from  well-marked  insufficiency  of  the 
aortic  valves,  with  considerable  hypertrophy  of  the  left  ventricle  and  left  auricle. 
The  ascent  is  steep,  caused  by  the  force  of  the  contracted  heart.  In  the  apex  of 
the  curve  are  two  projections,  A  is  the  anacrotic  auricular  wave,  and  V  is  the 
ventricular  wave.  Fig.  62,  II. ,  is  a  curve  obtained  from  the  subclavian  artery/  of 
the  same  indi\adual.  In  the  femoral  artery  the  auricular  projection  is  only 
obtained  when  the  friction  of  the  writing-style  is  reduced  to  the  minimum,  and 
when  it  occurs  it  immediately  precedes  the  beginning  of  the  ascent  (Fig.  62 
III.,  a).  The  pulse-curve,  in  cases  of  aortic  insufficiency,  is  also  characterised 
ty — (1)  its  considerable  height;  (2)  the  rapid  fall  of  the  lever  from  the  apex  of  the 
curve,  because  a  large  part  of  the  blood  which  is  forced  into  the  aorta  regurgitates 


148      INFLUENCE  OF  RESPIRATORY  MOVEMENTS  ON  PULSE-CURVE. 

into  the  left  ventricle  when  the  ventricle  relaxes;  (3)  not  unfrequently  a  pro- 
jection occurs  at  the  apex,  due  to  the  elastic  vibration  of  the  tense  arterial  wall ; 
(4)  the  dicrotic  wave  (R)  is  small  compared  with  the  size  of  the  curve  itself, 
because  the  pulse -wave,  owing  to  the  lesion  of  the  aortic  valves,  has  not  a  suflB- 
ciently  large  surface  to  be  reflected  from.  The  great  height  of  the  curve  is 
explained  by  the  large  amount  of  blood  projected  into  the  aortic  system  by  the 
greatly  hypertrophied  and  dilated  ventricle. 


74.  Influence  of  the  Respiratory  Movements  on 
the  Pulse-Curve. 

The  respiratory  movements  influence  the  pulse  in  two  ways :— (1) 
in  a  purely  physical  way,  by  diminishing  the  arterial  pressure  during 
each  inspiration  and  increasing  it  during  expiration;  (2)  the  respir- 
atory movements  are  accompanied  by  stimulation  of  the  vasomotor 
centre,  which  produces  variation  of  the  blood-pressure. 

(a.)  Normal  Respiration. — During  inspiration,  owing  to  the  dilatation 
of  the  thorax,  more  arterial  blood  is  retained  within  the  chest,  while  at 
the  same  time,  venous  blood  is  sucked  into  the  right  auricle  by 
aspiration;  as  a  consequence  of  this,  the  tension  in  the  arteries  during 
inspiration  must  be  less.  The  diminution  of  the  chest  during  expiration 
favours  the  flow  in  the  arteries,  while  it  retards  the  flow  of  the  venous 
blood  in  the  vense  cavse — two  factors  which  raise  the  tension  in  the 
arterial  system.  The  difference  of  pressure  explains  the  difference  in 
the  form  of  the  pulse-curve  obtained  during  inspiration  and  expiration, 
as  in  Fig.  63  and  Fig.  58,  I.,  III.,  IV.,  in  which  J  indicates  the  part  of 
the  curve  which  occurred  during  inspiration,  and  E  the  expiratory  por- 
tion. The  following  are  the  points  of  difference: — (1.)  The  greater  dis- 
tension of  the  arteries  during  expiration  causes  all  the  parts  of  the 


Fig.  63. 

Influence  of  the  respiration  upon  the  sphygmogram,  after  Riegel — J,  during  in- 
spiration; E,  during  expiration. 

curve  occurring  during  this  phase  to  be  higher;  (2.)  the  line  of 
ascent  is  lengthened  during  expiration,  because  the  expiratory  thoracic 
movement  helps  to  increase  the  force  of  the  expiratory  wave;    (3.) 


valsalva's  and  muller's  experiments.  149 

owing  to  the  increase  of  the  pressure  the  dicrotic  wave  must  be  less 
during  expiration;  (4.)  for  the  same  reason  the  elastic  elevations 
are  more  distinct  and  occur  higher  in  the  curve  near  its  apex.  The 
frequency  of  the  pulse  is  slightly  greater  during  expiration  than  during 
inspiration. 

(b.)  This  purely  mechanical  effect  of  the  respiratory  movements  is 
modified  by  the  simultaneous  stimulation  of  the  vasomotor  centre 
which  accompanies  these  movements.  At  the  beginning  of  inspiration 
the  blood-pressure  in  the  arteries  is  lowest,  but  it  begins  to  rise  during 
inspiration,  and  increases  until  the  end  of  the  inspiratory  act,  reaching 
its  maximum  at  the  beginning  of  expiration.  During  the  remainder 
of  the  expiration  the  blood-pressure  falls  until  it  reaches  its  lowest 
level  again  at  the  beginning  of  inspiration  (compare  §  85,  /),  the  pulse- 
curves  are  similarly  modified,  and  exhibit  the  signs  of  greater  or  less 
tension  of  the  arteries  corresponding  to  the  phases  of  the  respiratory 
movements  (Klemensiewicz,  Knoll,  Schreiber,  Lbwit).  [There  is,  as  it 
were,  a  displacement  of  the  blood-pressure  curve  relative  to  the  respira- 
tory curve.] 

Forced  Respiration. — With  regard  to  the  effect  produced  on  the 
pulse-curve  by  a  powerful  expiration  and  a  forced  inspiration,  observers 
are  by  no  means  agreed. 

Valsalva's  Experiment. — Strong  expiratory  pressure  is  best  produced 
by  closing  the  mouth  and  nose,  and  then  making  a  great  expiratory 
effort ;  at  first  there  is  increase  of  the  blood-pressure  and  the  formation 
of  pulse-waves  resembling  those  which  occur  in  ordinary  expiration, 
the  dicrotic  wave  being  less  developed ;  but,  when  the  forced  pressure 
is  long  continued,  the  pulse-curves  have  all  the  signs  of  diminished 
tension  (Eiegel,  Frank,  and  Sommerbrodt).  This  effect  is  due  to  the 
action  of  the  vasomotor  centre,  which  is  affected  reflexly  from  the 
pulmonary  nerves.  We  must  assume  that  forced  expiration,  such 
as  occurs  in  Valsalva's  experiment,  acts  by  depressing  the  activity  of 
the  vasomotor  centre  (compare  Vol.  ii.)  Coughing,  singing,  and  declaim- 
ing, act  like  Valsalva's  experiment,  while  the  frequency  of  the  pulse 
is  increased  at  the  same  time  (Sommerbrodt).  After  the  cessation 
of  Valsalva's  experiment,  the  blood-pressure  rises  above  the  normal  state 
(Sommerbrodt),  almost  as  much  as  it  fell  below  it;  the  normal  con- 
dition being  restored  within  a  few  minutes  (Lenzmann). 

Muller's  Experiment.— When  the  thorax  is  in  the  expiratory  phase, 
close  the  mouth  and  nose,  and  take  a  deep  inspiration  so  as  forcibly  to 
expand  the  chest  (§  60).  At  first  the  pulse-curves  have  the  char- 
acteristic signs  of  diminished  tension,  viz.,  a  higher  and  more  distinct 
dicrotic  wave;  then  the  tension  can,  by  nervous  influences,  be  in- 
creased, just  as  in  Fig.  64,  where  C  and  R  are  tracings  taken  from  the 


150    INFLUENCE   OF  RESPIRATORY  MOVEMENTS  ON  PULSE-CURVE. 

carotid  and  radial  arteries  respectively,  during  Miiller's  experiment, 
in  which  the  dicrotic  waves,  r,  r,  indicate  the  diminished  tension  in  the 
vessels.  In  Ci  and  E^,  taken  from  the  same  person  during  Valsalva's 
experiment,  the  opposite  condition  occurs. 


■ 


K 


Fig.  64. 

C,  curve  from  the  carotid,  and  R,  radial,  during  Miiller's  experiment ;  Ci  and  Rj, 
from  the  same  vessels  during  Valsalva's  experiment.  Curves  written  on  a 
vibrating  surface. 

On  expiring  into  a  vessel  resembling  a  spirometer  {see  Respiration),  (Waldenburg's 
respiration  apparatus),  and  filled  with  compressed  air,  the  same  result  is  obtained  as 
in  Valsalva's  experiment — the  blood-pressure  falls  and  the  pulse-beats  increase; 
conversely,  the  inspiration  from  this  apparatus  of  air  under  less  pressure  acts  like 
Miiller's  experiment,  i.e.,  it  increases  the  effect  of  the  inspiration,  and  afterwards 
increases  the  blood-pressure,  which  may  either  remain  increased  on  continuing  the 
experiment,  or  may  fall  (Lenzmann). 

The  inspiration  of  compressed  air  diminishes  the  mean  blood-pressure  (Zuntz), 
and  the  after-effect  continues  for  some  time.  The  pulse  is  more  frequent  both 
during  and  after  the  experiment.  Expiration  in  rarified  air  increases  the  blood- 
pressure  (Zuntz,  Lenzmann).  The  effects  which  depend  upon  the  action  of  the 
nervous  system  do  not  occur  to  the  same  extent  in  all  cases.  Exposure  to  com- 
jjressed  air  in  a  pneumatic  cabinet  lowers  the  pulse-curve,  the  elastic  vibrations 
become  indistinct,  and  the  dicrotic  wave  diminishes  and  may  disappear  (v. 
Vivenot).      The    heart's  beat  is  slowed    and  the  blood-pressure  raised    (Bert, 


Fig.  65, 

Pulsus  paradoxus,  after  Kussmaul — E,  expiration;  J,  inspiration. 

Jacobsohn,  Lazarus).    Exposure  to  rarified  air  causes  the  opposite  result,  which  is  a 
sign  of  diminished  arterial  tension. 


INFLUENCE   OF  PRESSURE   ON   FORM   OF   PULSE-CURVE.         151 

Pulsus  Paradoxus.— Under  pathological  conditions,  especially  when  there  is 
union  of  the  heart  or  its  large  vessels  with  the  surrounding  parts,  the  pulse  dur- 
ing inspiration  may  be  extremely  small  and  changed,  or  may  even  be  absent.  This 
condition  has  been  called  pulsus  paradoxus  (Griesinger,  Kussmaul). 

It  depends  upon  a  diminution  of  the  arterial  lumen  during  the  inspiratory  move- 
ment. Even  in  health,  it  is  possible  by  a  change  of  the  inspiratory  movement  to 
produce  the  p,  paradoxus  (Riegel,  Sommerbrodt). 


75.  Influence  of  Pressure  upon  the  Form  of  the 
Pulse-Curve. 

It  is  most  important  to  know  the  actual  pressure  which  is  applied  to  an  artery 
while  a  sphygmogram  is  being  taken.  The  changes  affect  the/orm  of  the  curve  as 
well  as  the  relation  of  the  individual  parts  thereof.  In  Fig.  66,  a,  h,  c,  d,  e,  are 
radial  curves ;  a  was  taken  with  minimal  pressure,  b  with  100,  c  200,  d  250,  and  e 
450  grammes  pressure,  while  A,  B,  C,  D,  show  the  relations  as  to  the  time  of 
occurrence  of  the  individual  phenomena  where  the  weight  was  successively 
increased.  The  study  of  these  curves  yields  the  following  results:— (1)  When  the 
weight  is  small,  the  dicrotic  wave  is  relatively  less ;  the  whole  curve  is  high.  (2) 
With  a  moderate  weight  (100  -  200  grammes)  the  dicrotic  wave  is  best  marked,  the 
whole  curve   is  somewhat  lower.     (3)  On  increasing  the  weight,  the  size  of  the 


ZOO 


230 


450 


vt- 


A  100 


B  170 


C220 


D240 


Fig.  66. 


Various  forms  of  curves  (radial)  obtained  by  gradually  increasing  the  pressure. 


A 

B 

C 

D 

1-2, 

.    S| 

6 

■  54 

44 

1— a, 

— 

Hi 

10 

94 

1—3, 

.   18 

17 

164 

15 

1^, 

.   25 

234 

234 

22 

1—5, 

.   34 

32 

32 

29| 

1— b. 

— 

41 

— 

— 

1-6, 

.   44 

46i 

45 

464 

152  RAPIDITY  OF  TRANSMISSION   OF  PULSE-WAVES. 

dicrotic  wave  again  diminislies.  (4)  The  fine  elastic  vibrations  preceding  the 
dicrotic  wave  appear  first  when  a  weight  of  220  to  300  grammes  is  used.  (5)  The 
rapidity  of  the  pulse  changes  with  increasing  weight,  the  time  occupied  by  the 
ascent  becoming  shorter,  the  descent  becoming  longer.  (6)  The  height  of  the  entire 
curve  decreases  as  the  weight  increases.  In  every  sphygmogram  the  pressure 
under  which  it  was  obtained  ought  always  to  be  stated. 

In  Fig.  66,  A,  B,  C,  D,  are  curves  obtained  from  the  radial  artery  of  a  healthy 
student.  The  pressure  exerted  upon  the  artery  for  A  was  100 ;  B,  170 ;  C,  220 ; 
and  D,  240  grms.     The  time  occupied  by  the  various  events  was : — 


1  vibration 
=  0-01613 

sec. 


If  pressure  he  exerted  upon  an  artery  for  a  long  time  the  strength  of  the  pulse  is 
gradually  increased.  If,  after  subjecting  an  artery  to  considerable  pressure,  a 
lighter  weight  be  used,  not  unfrequently  the  pulse-curve  assumes  the  form  of  a 
dicrotic  pulse,  owing  to  the  greater  development  of  the  dicrotic  elevation.  When 
strong  pressure  is  applied,  the  blood  is  forced  to  find  its  way  through  collateral 
channels.  When  the  chief  artery  ceases  to  be  compressed,  the  total  area  is,  of 
course,  considerably  and  suddenly  enlarged,  which  results  in  the  production  of  a 
dicrotic  elevation.  Fig.  58,  X,  is  such  a  dicrotic  curve  obtained  after  considerable 
pressure  had  been  applied  to  the  artery. 

76.  Rapidity  of  Transmission  of  Pulse- Waves. 

Tlie  pulse-wave  proceeds  throughout  the  arterial  system  from  the 
root  of  the  aorta,  so  that  the  pulse  is  felt  sooner  in  parts  lying  near  the 
heart  than  in  the  peripheral  arteries.  E.  H.  Weber  ca,lculated  the 
rate  of  the  pulse-wave  as  9'240  metres  [28^  feet]  per  sec.  from  the 
diflference  in  time  between  the  pulse  in  the  external  maxillary  artery 
and  the  dorsal  artery  of  the  foot.  Czermak  showed  that  the  elasticity 
was  not  equal  in  all  the  arteries,  so  that  the  velocity  of  the  pulse-wave 
cannot  be  the  same  in  all.  The  pulse-wave  is  propagated  more  slowly 
in  the  arteries  with  soft  extensile  walls  than  in  arteries  with  resistant 
and  thick  walls,  so  that  it  is  transmitted  more  rapidly  in  the  arteries 
of  the  lower  extremities  than  in  those  of  the  upper.  It  is  still  slower 
in  children. 

77.  Propagation  of  the  Pulse-Wave  in  Elastic 

Tubes. 

Waves  similar  to  the  pulse  may  be  produced  in  elastic  tubes.  (1)  According  to 
E.  H.  Weber  the  velocity  of  propagation  of  the  waves  is  11 '295  metres  per  sec; 


PROPAGATION   OF  PULSE-WAVES  IN   ELASTIC  TUBES. 


153 


according  to  Bonders,  11-14  metres  (34  -  43  feet).  (2)  According  to  E.  H.  Weber 
increased  internal  tension  causes  only  an  inconsiderable  decrease ;  Rive  found  a 
great  decrease ;  Bonders  found  no  obvious  diflference ;  while  Marey  found  an  increased 
velocity.  (3)  Bonders  found  the  velocity  to  be  the  same  in  tubes,  2  mm.  in  dia- 
meter, as  in  wider  tubes,  but  Marey  believes  that  the  velocity  varies  when  the 
diameter  of  the  tube  changes.  (4)  The  velocity  is  less  the  smaller  the  elastic 
coefficient.  (5)  The  velocity  increases  with  increased  thickness  of  the  wall,  while 
it  diminishes  when  the  specific  gravity  of  the  fluid  increases. 

Moens  has  recently  formulated  the  following  laws  as  to  the  velocity  of  propaga- 
tion of  waves  in  elastic  tubes: — (1)  It  is  inversely  proportional  to  the  square  root 
of  the  specific  gi-avity  of  the  fluid.  (2)  It  is  as  the  square  root  of  the  thickness 
of  the  wall,  the  lateral  pressure  being  the  same.  (3)  It  is  inversely  as  the  square 
root  of  the  diameter  of  the  tube,  the  lateral  pressure  being  the  same.  (4)  It  is 
as  the  square  root  of  the  elastic  coefficient  of  the  wall  of  the  tube,  the  lateral 
pressure  being  the  same  (Valentin). 

Experiments  with  CaOUtcllOllC  Tubes. — For  this  purpose  Landois  employs 
the  following  apparatus  (Fig.  67):— A  large  tuning-fork,  A  (35  cmtr.  long),  carries 
on  one  of  its  arms  a  glass-plate,  P  (25  cmtr.  long,  and  5  cmtr.  broad),  while  the  other 
arm  is  weighted,  G.  The  tuning-fork  is  fixed  by  an  iron  holder,  T,  to  a  movable 
piece  of  wood  which  can  be  pushed  along  with  the  hand  in  a  groove  on  a  support 
H,  H.  When  the  glass-plate  is  smoked,  the  curved  needle  of  the  angiograph 
writes  its  movements  upon  it.  The  fork,  when  it  vibrates,  makes  little  teeth  in 
the  curve,  and  the  value  of  each  vibi-ation  is  estimated  befoi'ehand.  Every  com- 
plete vibration  in  this  instrument  is  equal  to  0 '01613  sec. 

Velocity  of  the  Waves  in  Elastic  Tuhes  filled  with  Water  or  Mercury. 

— Take  a  soft  extensible  elastic  tube,  A,  8  "80  metres   long,   1    mm.   thick,  and 


Fig.  67. 


Instrument  for  measuring  the  velocity  of  the  pulse-wave  in  an  elastic  tube  con- 
taining water  or  mercury— A,  tuning-fork;  B,  ampulla;  A,  elastic  tube;  P, 
glass-plate  smoked j  Q,  manometer;  x,  pad  of  lever  of  angiograph;  writing- 
style,  B. 


154  VELOCITY  OF  TKE  PtTLSE-WAVE  IN  MAN. 

7  mm.  diameter.  If  1  metre  of  the  tube  is  weighted  with  1  kilo,  it  elongates  68 
cmtr.  An  ampulla,  B,  capable  of  containing  50  cmtr.,  is  fixed  to  one  end  of  the 
tube,  while  to  the  other  end  of  the  ampulla  is  fixed  a  mercurial  manometer,  Q. 


Fig.  67a. 

Pulse-curve  from  an  elastic  tube  registered  upon  a  plate  attached  to  a  vibrating 

tuning-fork. 

The  tube,  A,  is  shut  close  to  the  ampulla  every  time  the  pressure  is  mea- 
sured, in  order  to  obviate  the  occurrence  of  oscillation  in  the  mercury.  A  certain 
portion  of  the  tube,  say  8  metres,  is  measured.  The  beginning,  a,  and  end,  6, 
of  this  stretch  of  tubing  are  placed  under  the  pad,  x ,  of  the  angiograph.  When 
a  positive  wave  is  produced  by  compressing  the  ampulla,  the  writing-lever  is  raised 
twice,  the  first  time  when  the  wave  passes  the  first  part  of  the  tube,  a,  under  the 
pad,  and  the  second  time  when  the  end  part  of  the  tube,  b,  is  distended  by  the 
wave.  The  curve  obtained  is  shown  in  Fig.  67a,  in  which  the  two  elevations, 
1  and  2,  are  obvious.  The  time  between  the  two  may  be  ascertained  by  covmting 
the  number  of  vibrations  of  the  tuning-fork.  The  experiments  gave  the  following 
results : — 

(A.)  The  velocity  of  the  wave  is  11 '809  metres  per  sec. 

(B.)  The  intra-vascular  jpressure  has  a  decided  influence  on  the  velocity:  thus, 
in  the  tube,  A,  with  18  cmtr.  (Hg.)  pressure,  the  velocity  per  metre  =  0*093  sec, 
while  with  21  cmtr.  pressure  (Hg.)  =  0'095  sec.  per  metre. 

(C.)  The  specific  gravity  of  the  liquid  influences  the  velocity  of  the  pulse-wave. 
In  mercury  the  wave  is  propagated  four  times  more  slowly  than  in  water  (Marey 
and  Landois). 

(D.)  The  velocity  in  a  tube  which  is  more  rigid  and  not  so  extensile  is  greater 
than  in  a  tube  which  is  easily  distended. 

78.  Velocity  of  the  Pulse- Wave  in  Man. 

Landois  obtained  the  following  results  in  a  student  whose  height  was  174  centi- 
metres :— Difference  between  carotid  and  radial  =  0*074  sec.  (the  distance  being 
taken  as  62  centimetres);  carotid  and  femoral =0*068  sec;  femoral  (inguinal 
region)  and  posterior  tibial  =  0*097  sec  (distance  estimated  at  91  centimetres). 

The  velocity  of  the  pulse-wave  in  the  arteries  of  the  upper  extre- 
mities =  9*43  metres  per  sec,  and  in  those  of  the  lower  extremity  9*40 
metres  per  second.     The  velocity  is  greater  in  the  less  extensible  arteries 


VELCCITY   OF  THE  PULSE-^VAVE   IN  MAX. 


155 


of  the  lower  extremities  than  in  those  of  the  upper  limb.  For  the  same 
reason  it  is  less  in  the  peripheral  arteries  and  in  the  yielding  arteries 
of  children  (Czermak). 

E.  H.  Weber  estimated  the  velocity  at  9-24  metres  per  sec;  Garrod,  9 -10' 8 
metres;  Grashey,  8'5  metres;  Moens,  8" 3  metres,  and  -with  diminished  pressure 
during  Valsalva's  experiment  (p.  112)  7"3  metres. 

In  animals,  haemorrhage  (Haller),  slowing  of  the  heart  produced  by  stimulation 
of  the  vagus  (Moens),  section  of  the  spinal  cord,  deep  morphia-narcosis,  and  dilata- 
tion of  blood-vessels  by  heat,  produce  slowing  of  the  velocity,  while  stimulation  of 
the  spinal  cord  accelerates  it  (Gnmmach). 

The  wave-length  of  the  pulse-wave  is  obtained  by  multiplying  the 
duration  of  the  inflow  of  blood  into  the  aorta=0'08  to  0"09  sees, 
(p.  86)  by  the  velocity  of  the  pulse-wave. 

Method. — Place  the  knobs  of  two  tambours  (Fig.  52)  upon  the  two  arteries  to 
be  investigated,  or  place  one  over  the  apex-beat  and  the  other  upon  an  artery. 
These  receiving  tambours  are  connected  with  two  registering  tambours,  as  in 
Brondgeest's  pansphygmograph  (§  67,  Fig.  52)  so  that  their  writing-levers  are 
directly  over  each  other,  and  so  arranged  as  to  wi'ite  simultaneously  on  one  vibrating- 
plate  attached  to  a  tuning-fork.  [Or  they  may  be  made  to  write  upon  a  revolving 
cylinder,  whose  rate  of  movement  is  ascertained  by  causing  a  tuning-fork  of  a 
known  rate  of  vibration  to  wi-ite  under  them.]  In  Fig.  68,  H  is  the  curve  obtained 
from  the  heart,  and  C  from  the  radial  arterj'.  The  apparatus  is  improved  by  using 
rigid  tubes  and  filling  them  with  water,  in  which  all  impulses  are  rapidly  communi- 
cated. In  arteries  which  are  distant  from  each  other,  or  in  the  case  of  the  heart 
and  an  artery,  the  two  knobs  of  the  receiving  tambours  may  be  connected  by  means 
of  a  Y-tube  -with  one  writing-lever.  In  Fig.  68,  B  is  a  curve  fi-om  the  radial  artery 
taken  in  this  way.  In  it  v  H  F  indicates  contraction  of  the  ventricle ;  H,  the 
apex  of  the  ventricular  contraction  ;  P,  the  primary  apex  of  the  radial  curve  ;  v,  the 


A,  curve  of  radial  artery  on  a  vibrating  surface  (1  vib.  =0*01613  sec.) ;  P,  apex 
of  curve  ;  e,  e,  elastic  vibrations ;  R,  dicrotic  wave  ;  B,  curve  of  same  radial 
taken  along  with  the  heart-beat ;  v,  H,  P,  contraction  of  the  ventricle ;  H, 
curve  of  the  heart-beat ;  C,  of  the  radial  artery,  taken  simultaneously.  The 
arrows  indicate  the  identical  points  in  both  curves.    In  B,  v  to  /^  =  9  vibrations. 


156 


FURTHER  PULSATILE   PHENOMENA. 


beginning  of  tlie  ventricular  contraction ;  p,  of  the  radial  pulse.  A  ia  the  curve  of 
the  radial  artery  alone.  From  these  curves,  as  well  as  from  H  and  C,  it  is  evident 
that  in  this  instance  9  vibrations  occur  between  the  beginning  of  the  ventricular 
contraction  (in  H  at  22)  until  the  beginning  of  the  pulse  in  the  radial  artery  (in  C 
at  13),  so  that  0"  15  sec.  elapses  between  these  two  events  (1  vibration =0" 01613  sec). 
In  Fig.  69  the  difference  between  the  carotid  and  the  posterior  tibial  pulse= 
0-137  sec. 


Tib.fpost.  I 

Carot. 


Fig.  69. 
Curves  of  the  carotid  and  posterior  tibial  taken  simultaneously  with  Brondgeest's 
pansphygmograph  writing  upon  a  vibrating  plate,  attached  to  a  tuning-fork. 
The  arrows  indicate  the  identical  moment  of  time  in  each  curve. 

Fa>thologiC£ll. — In  cases  of  diminished  extensibility  of  the  arteries,  e.g.,  in 
atheroma  (p.  127),  the  pulse-wave  is  propagated  more  rapidly.  Local  dilatations  of 
the  arteries,  as  in  aneurisms,  cause  a  retardation  of  the  wave,  and  a  similar  result 
arises  from  local  constrictions.  Relaxation  of  the  walls  of  the  vessels  in  high 
fever  retards  the  movement  (Hamernjk). 

79.    Further  Pulsatile  Phenomena. 

1.  In  the  mouth  and  nose,  when  they  are  filled  with  air,  and  the  glottis 
closed,  pulsatile  phenomena  (due  to  the  arteries  in  their  soft  parts),  may  be  foimd 
communicating  a  movement  to  the  contained  air.  The  curves  obtained  are 
relatively  small,  and  closely  resemble  the  curve  of  the  carotid.  A  similar  pulse 
is  obtained  in  the  tympanum  with  intact  membrana  tympani,  and  when  the 
soft  parts  of  the  tympanum  are  congested  (Schwartze,  Troltsch). 

2.  Entoptical  Pulse, — After  violent  exercise,  an  illumination  corresponding  to 
each  pulse-beat,  occurs  on  a  dark  optical  field.  When  the  optical  field  is  bright, 
an  analogous  darkening  occurs  (Landois).  The  ophthalmoscope  occasionally  reveals 
pulsation  of  the  retinal  arteries  ( Jager),  which  becomes  marked  in  insufficiency  of 
the  aortic  valves  (Quincke,  O.  Becker,  Helfreich). 

3.  Pulsatile  Muscular  Contraction. — The  orbicularis  'palpebrarum  muscle 
contracts  under  similar  conditions  synchronously  with  the  pulse ;  and  it  is  perhaps 
due  to  the  pulse-beat  exciting  the  sensory  nerves  reflexly.  The  brothers  Weber 
found  that  not  unfrequently  while  walking,  the  step  and  pulse  gradually  and  in- 
voluntarily coincide. 

4.  When  the  legs  are  crossed  as  one  sits  in  a  chair,  the  leg  which  is  supported 
is  raised  with  each  pulse-beat,  and  it  gives  also  a  second  or  dicrotic  elevation. 

.5.  If,  while  a  person  is  quite  quiet,  the  incisor  teeth  of  the  lower  jaw  be  made 
just  to  touch  the  upper  incisors  very  lightly,  we  detect  a  double  beat  of  the  lower 


VIBRATIONS  COMMUNICATED  TO  THE  BODY  BY  THE  HEART.       157 

against  the  upper  teeth,  owing  to  the  pulse-beat  in  the  external  maxillary  artery 
raising  the  lower  jaw.  The  second  elevation  is  due  to  the  closure  of  the  semi-lunar 
valves,  and  not  to  a  dicrotic  wave. 

6.  Brain  and  FontanelleS. — The  large  arteries  at  the  base  of  the  brain  com- 
municate a  movement  to  it,  while  similar  movements  occur  with  respiration — rising 
during  expiration  and  falling  during  inspiration.  These  movements  are  visible 
in  the  fontanelles  of  infants.  The  respiratory  movements  depend  upon  variations  in 
the  amount  of  blood  in  the  veins  of  the  cranial  cavity,  and  also  upon  the  respiratory 
variations  of  the  blood-pressure. 

7.  Amongst  pathologfical  phenomena,  are  tlie  beating  in  the  epigastrium,  as  in 
hypertrophy  of  the  right  or  left  ventricle,  caused,  it  may  be,  by  deep  insertion  of 
the  diaphragm,  and  it  may  be  partly  by  the  beating  of  a  dilated  abdominal  aorta  or 
coeliac  axis. 

Abnormal  dilatations  (aneurisms)  of  the  arteries  cause  an  abnormal  pulsation, 
while  theyproducea  slowing  inthe  velocity  of  thepulse-tvaveinthecorresi^ondhigaxtery. 
Hence  the  pulse  appears  later  in  such  an  artery  than  in  the  artery  on  the  healthy 
side.  Hypertrophy  and  dilatation  of  the  left  ventricle  cause  the  arteries  near  the 
heart  to  pulsate  strongly.  In  the  analogous  condition  of  the  right  ventricle,  the  beat 
of  the  pulmonary  artery  may  be  seen  and  felt  in  the  second  left  intercostal  space. 

80.    Vibrations  communicated  to  the  Body  by  the 
action  of  the  Heart. 

The  beating  of  the  heart  and  large  arteries  communicates  vibrations  to  the  body 
as  a  whole,  but  the  vibration  is  not  simple  but  compound. 

Gordon  was  the  first  to  represent  this  pulsatory  vibration  graphically.     If  a 


/A 

/M-7/ 

/     B 

/ 

Q 

D 

Jit 

m 

/// 

_//////_ 

K 

-ll_ 

~  / 

n 


Fig.  70. 


n, 


Elastic  support  for  registering  the  molar  motions  of  the  body— K,  a  wooden 
box ;  B,  feet  of  patient ;  j),  cardiograph  ;  a,  b,  elastic  tubing.  I,  III— Vibra- 
tion curves  of  a  healthy  person.  IV— Similar  curve  obtained  from  a  patient 
suffering  from  insufficiency  of  the  aortic  valves  and  great  hypertrophy  of  the 
heart. 


158       VIBRATIONS  COMMUNICATED  TO  THE  BODY  BY  THE  HEART. 

person  be  placed  in  an  erect  attitude  in  the  scale  of  a  large  balance,  the  index 
o&cillates,  and  its  movements  coincide  with  the  heart's  movements. 

Fig.  70,  I,  shows  a  curve  obtained  by  Gordon,  wrritten  directly  by  the  index  of 
the  spring  balance.  The  lowest  part  of  the  curve  corresponds  to  the  systole  of  the 
ventricle. 

Landois  employed  the  following  arrangement : — Take  a  long  four-sided  box,  K, 
open  at  the  top,  and  arrange  several  coils,  a,  b,  of  stout  caoutchouc  tubing  round 
one  end.  A  wooden  board,  B,  smaller  than  the  opening  in  the  box,  is  so  placed 
that  it  rests  with  one  end  on  the  caoutchouc  tubing,  and  with  the  other  on  the 
narrow  end  of  the  box.  The  person  to  be  experimented  upon,  A,  stands  vertically 
and  firmly  on  this  board.  A  receiving  tambour,  p,  is  placed  against  the  surface 
of  the  board  next  the  elastic  tube,  which  registers  the  vibrations  of  the  foot 
support.  Fig.  Ill  is  a  curve  showing  such  vibrations,  each  heart-beat  being  followed 
in  this  case  by  four  oscillations.  It  corresponds  to  I.  To  ascertain  the  relations 
and  causes  of  these  vibrations,  it  is  necessary  to  obtain,  simultaneously,  a  tracing 
of  the  heart  and  the  vibratory  curve.  For  this  purpose  use  the  two  tambours  of 
Brondgeest's  pansphygmograph  (p.  71),  placing  one  nob  or  pad  over  the  heart, 
and  the  other  on  the  foot-support,  and  allow  the  writing-tambours  to  inscribe  their 
vibrations  on  a  glass-plate  attached  to  a  tuning-fork. 

In  the  lovjer  or  cardiac  impulse  curve,  Fig.  71,  the  rapidly-rising  part  is  due  to 
the  ventricular  systole.  It  contains  8  vibrations  (1  vib.=0" 01613  sec).  The 
beginning  of  the  ventricular  systole  is  indicated  in  the  fig.  by  -  36  -  3  - 17. 

If  the  corresponding  numbers  in  the  upper  or  vibratory  curve  are  studied,  it  is 
obvious  that  at  the  moment  of  ventricular  systole  the  body  makes  a  downward  vibration, 
i.e.,  it  exercises  greater  pressure  upon  the  foot  -  support.  Gordon  interprets  his 
curve  as  giving  exactly  the  opposite  result.  This  downward  motion,  however, 
lasted  only  during  5  vibrations  of  the  tuning-fork :  during  the  last  3  vibrations, 
corresponding  to  the  systole,  there  is  an  ascent  of  the  body  corresponding  to  a  less 
pressure  upon  the  foot-plate.  When  the  ventricle  empties  itself,  it  undergoes  a 
movement  in  a  downward  and  outward  direction — Gutbrodt's  "reaction  impulse." 


36       ■       f                W.     ,,'20 

1 

4. 

■     "       K                              '        f\    ' 

/\ 

/  \  20  •      ■   /  v  ^° 

/ 

\1 

■  ^''- -.'  n  / 

H 

30     _jy'  :  ■ 

\ 

Fig.  71. 

The  upper  curve  is  the  vibration-curve  of  a  healthy  person,  and  the  lower  one  a 
tracing  of  the  apex  beat. 

In  the  upper  curve  analogous  numbers  are  employed  to  indicate  the  vibrations 
occurring   simultaneously,   viz., -28-11 -10.      The   closure   of  the    semi-lunar 


THE   BLOOD-CURRENT.  159 

valves  is  well  marked  in  the  three  heart-beats  at  20-20.  This  closure  is 
indicated  in  analogous  points  in  both  curves,  after  which  there  is  a  descent  of  the 
foot-support,  and  this  corresponds  to  the  downward  propagation  of  the  pulse-wave 
through  the  aorta  to  the  vessels  of  the  feet. 

In  insufficiency  of  the  aortic  valves,  as  shown  in  Fig.  70,  IV,  the  vibration  com- 
municated to  the  body  is  very  considerable. 

81.  The  Blood-Current. 

The  closed  and  much-branched  vascular  system,  whose  walls  are 
endowed  with  elasticity  and  contractility,  is  not  only  completely 
filled  with  blood  but  it  is  over-filled.  The  total  volume  of  the  blood  is 
somewhat  greater  than  the  capacity  of  the  entire  vascular  system. 
Hence  it  follows  that  the  mass  of  blood  must  exert  pressure  on  the 
walls  of  the  entire  system,  thus  causing  a  corresponding  dilatation  of 
the  elastic  vascular  walls  (Brunner).  This  occurs  only  during  life; 
after  death  the  muscles  of  the  vessels  relax,  and  fluid  passes  into  the 
tissues,  so  that  the  blood-vessels  come  to  contain  less  fluid  and  some 
of  the  vessels  may  be  emptied. 

If  the  blood  were  uniformly  distributed  throughout  the  vascular 
system  and  under  the  same  pressure,  it  would  remain  in  a  position  of 
equilibrium  (as  after  death).  If,  however,  the  pressure  be  raised  in 
one  section  of  the  tube  the  blood  will  move  from  the  part  where  the 
pressure  is  higher  to  where  it  is  lower ;  so  that  the  blood-current  is  a 
result  of  the  difference  of  ^pressure  within  the  vascular  system.  If  either 
the  aorta  or  the  venae  cavse  be  suddenly  ligatured  in  a  living  animal, 
the  blood  continues  to  flow,  gradually  more  slowly,  until  the  diff'erence 
of  pressure  is  equalised  throughout  the  entire  vascular  system. 

The  velocity  of  the  current  will  be  greater  the  greater  the  difference 
of  pressure,  and  the  less  the  resistance  opposed  to  the  blood-stream. 

The  difference  of  pressure  which  causes  the  current  is  produced  hj  the 
heart  (E.  H.  Weber).  Both  in  the  systemic  and  pulmonary  circulations 
the  point  of  highest  pressure  is  in  the  root  or  beginning  of  the  arterial 
system,  while  the  point  of  lowest  pressure  is  in  the  terminal  portion  of 
the  venous  orifices  at  the  heart.  Hence,  the  blood  flows  continually 
from  the  arteries  through  the  capillaries  into  the  venous  trunks. 

The  heart  keeps  up  the  diff'erence  of  pressure  required  to  produce 
this  result ;  with  each  systole  of  the  ventricles  a  certain  quantity  of 
blood  is  forced  into  the  beginning  of  the  arteries,  while  at  the  same 
time  an  equal  amount  flows  from  the  venous  orifices  into  the  auricles 
during  their  diastole  (E.  H.  Weber). 

Bonders  added  another  important  fact — viz.,  that  the  action  of  the 
heart  not  only  causes  the  difference  of  pressure  necessary  to  establish  a 
blood-current,  but  that  it  also  raises  the  mean  pressure  within  the  vascular 


160  THE  BLOOD-CURRENT. 

system.  The  terminations  of  the  veins  at  the  heart  are  wider  and 
more  extensible  than  the  arteries  where  they  arise  from  the  heart. 
As  the  heart  propels  a  volume  of  blood  into  the  arteries  equal  to  that 
which  it  receives  from  the  veins,  it  follows  that  the  arterial  pressure 
must  rise  more  rapidly  than  the  venous  pressure  diminishes,  since  the 
arteries  are  not  so  wide  nor  so  extensible  as  the  veins.  Thus  the  total 
pressure  must  also  increase. 

The  volume  of  blood  expelled  from  the  ventricles  at  every  systole 
would  give  rise  to  a  jerky  or  intermittent  movement  of  the  blood 
stream — 1.  if  the  tubes  had  rigid  walls,  as  in  such  tubes  any  pressure 
exerted  upon  their  contents  is  propagated  momentarily  throughout  the 
length  of  the  tube,  and  the  motion  of  the  fluid  ceases  when  the  pro- 
pelling force  ceases.  2.  The  flow  would  also  be  intermittent  in 
character  in  elastic  tubes  if  the  time  between  two  successive  systoles 
were  longer  than  the  duration  of  the  current  necessary  for  the  compen- 
sation of  the  difference  of  pressure  caused  by  the  systole.  If  the  time 
between  two  successive  systoles  be  shorter  than  the  time  necessary  to 
equilibrate  the  pressure,  the  current  will  become  continuous,  provided 
the  resistance  at  the  periphery  of  the  tube  be  sufficiently  great  to  bring 
the  elasticity  of  the  tube  into  action.  The  more  rapidly  systole  follows 
systole,  the  greater  becomes  the  difference  of  pressure,  and  the  more 
distended  the  elastic  walls.  Although  the  current  thus  produced  is  con- 
tinuous, a  sudden  rise  of  pressure  is  caused  by  the  forcing  in  of  a  mass 
of  blood  at  every  systole,  so  that  with  every  systole  there  is  a  sudden 
jerk  and  acceleration  of  the  blood-stream  corresponding  to  the  pulse 
(compare  §  64). 

This  sudden  jerk-like  acceleration  of  the  blood-current  is  propagated 
throughout  the  arterial  system  with  the  velocity  of  the  pulse-wave : 
both  phenomena  are  due  to  the  same  fundamental  cause.  Every 
pulse-beat  causes  a  temporary  rapid  progressive  acceleration  of  the 
particles  of  the  fluid.  But  just  as  the  form-movement  of  the  pulse  is 
not  a  simple  movement,  neither  is  the  pulsatile  acceleration  a  simple 
acceleration.  It  follows  the  course  of  the  development  of  the  pulse- 
wave.  The  pulse-curve  is  the  graphic  representation  of  the  pulsatory 
acceleration  of  the  blood-stream.  Every  rise  in  the  curve  corresponds 
to  an  acceleration,  every  depression  to  a  retardation  of  the  current. 

Method. — These  facts  are  capable  of  demonstratiou  by  means  of  very  simple 
physical  experiments.  [Tie  a  Higgrnson's  syringe  to  a  piece  of  an  ordinary  gas- 
pipe.  On  forcing  water  through  the  tube  by  compressing  the  elastic  pump,  the 
water  will  flow  out  at  the  other  end  of  the  tube  in  jets,  while  during  the  intervals 
of  pulsation  no  water  will  flow  out.  As  the  walls  of  the  tube  are  rigid,  just  as 
much  fluid  flows  out  as  is  forced  into  the  tube.  If  a  similar  arrangement  be  made, 
and  a  long  elastic  tube  be  used,  a  continuous  outflow  is  obtained,  provided  the 
pulsations  occur  with  sufficient  rapidity  and  the  length  of  the  tube,  or  the  resist- 


CURRENT   IN   THE   CAPILLARIES.  161 

ance  at  its  periphery,  be  sufficient  to  bring  the  elasticity  of  the  tube  into  action. 
This  can  be  done  by  putting  a  narrow  cannula  in  the  outflow  end  of  the  tube,  or 
by  placing  a  clamp  on  it  so  as  to  diminish  the  exit  aperture.  This  apparatus 
converts  the  intermittent  flow  into  a  continuous  ciirrent.]  The  fire-engine  is  a 
good  example  of  the  conversion  of  an  intermittent  inflow  into  a  uniform  outflow.  The 
air  in  the  reservoir  is  in  a  state  of  elastic  tension,  and  it  represents  the  elasticity 
of  the  vascular  walls.  When  the  pump  is  worked  slowly,  the  outflow  of  the  water 
occurs  in  jets,  and  is  interrupted.  If  the  pumping  movement  be  sufficiently  rapid, 
the  compressed  air  in  the  reservoir  causes  a  continuous  outflow,  which  is  distinctly 
accelerated  at  every  movement  of  the  pump. 

Current  in  the  Capillaries. — In  the  capillary  vessels  the  pulsatile 
acceleration  of  the  current  ceases  with  the  extinction  of  the  pulse- 
wave.  The  great  resistance  which  is  offered  to  the  current  towards 
the  capillary  area  causes  both  to  disappear.  It  is  only  when  the 
capillaries  are  greatly  dilated,  and  when  the  arterial  blood-pressure 
is  high,  that  the  pulse  is  propagated  through  the  capillaries  into  the 
beginning  of  the  veins.  A  pulse  is  observed  in  the  veins  of  the  sub- 
maxillary gland  after  stimulation  of  the  chorda  tympani  nerve,  which 
contains  the  vascular  or  vaso-dilator  nerves  for  the  blood-vessels  of 
this  gland.  If  the  finger  be  constricted  with  an  elastic  band  so  as  to 
hinder  the  return  of  the  venous  blood,  and  to  increase  the  arterial 
blood-pressure,  while  at  the  same  time  dilating  the  capillaries,  an  inter- 
mittent increased  redness  occurs,  which  corresponds  with  the  well- 
known  throbbing  sensation  in  the  swollen  finger.  This  is  due  to  the 
capillary  pulse.  [Roy  and  Graham  Brown  found  that  pulsatile  pheno- 
mena were  produced  in  the  capillaries,  by  increasing  the  extra-vascular 
pressure  (p.  173).  Quincke  called  attention  to  the  capillary  pulse  which 
can  often  be  seen  under  the  finger  nails.  Extend  the  fingers  completely, 
when  a  whitish  area  appears  under  the  nails.  A  red  area  near  the  free 
margin  of  the  nail  advances  and  retires  with  each  pulse-beat.  It  is 
well-marked  in  some  diseased  conditions  of  the  heart,  and  is  probably 
produced  by  increased  extra-vascular  pressure.] 

82.  Schemata  of  the  Circulation. 

E.  H.  Weber  constructed  a  scheme  of  the  circulation.  It  consisted  of  a  force- 
pump  with  properly  arranged  valves  to  represent  the  heart,  portions  of  gut  for 
the  arteries  and  veins,  and  a  piece  of  glass  tubing  containing  a  piece  of  sponge  to 
represent  the  capillaries.  Various  schemes  have  been  invented,  including  the  very 
complicated  one  of  Marey  [and  the  thoroughly  practical  one  of  Rutherford]. 

83,  Capacity  of  the  Ventricles. 

Since  the  right  and  left  ventricles  contract  simultaneously,  and 
just  the   same   volume  of   blood  passes  through   the  pulmonary   as 

11 


162  ESTIMATION   OF  THE  BLOOD-PRESSURE, 

through  the  systemic  circulation,  it  follows  that  the  right  ventricle  must 
be  just  as  capacious  as  the  left.  The  capacity  of  the  ventricles  has 
been  estimated  in  the  following  ways : — 

(1.)  Directly,  by  filling  the  dead  ventricle  with  blood  (Santorini,  1724;  Legallois 
and  Collin).  This  method  is  unsatisfactory  and  inaccurate.  (2.)  All  the  vessels  of 
the  relaxed  heart  are  ligatured,  the  heart  excised,  and  the  contents  of  the  cavities 
estimated  (Abegg,  1848).  (3.)  Volkmann  estimated  the  capacity  to  be  ^^  of  the 
body-weight — i.e.,  for  a  man  of  75  kilos.  =  187 "5  grms. 


84.  Estimation  of  the  Blood-Pressure. 

(A.)  In  Animals :  Method  of  Hales. — The  Rev.  Stephen  Hales  (1727)  was 
the  first  to  introduce  a  long  glass  tube  into  a  blood-vessel  in  order  to  estimate  the 
blood-pressure  by  measuring  the  height  of  the  column  of  blood,  i.  e. ,  how  high  the 
blood  rose  in  the  tiibe.  The  tube  was  provided  at  its  lower  end  with  a  copper 
tube  bent  at  a  right  angle  (Pitot's  tube).  [The  tube  he  used  was  one-sixth  of  an 
inch  bore  and  about  nine  feet  long,  and  was  inserted  into  the  femoral  artery  of  a 
horse.  The  height  to  which  the  blood  rose  in  the  tube  was  noted,  as  well  as  the 
oscillations  that  occurred  with  every  pulsation.  From  the  height  of  the  column 
of  fluid  he  calculated  the  force  of  the  heart.] 

(2.)  The  Haemadynamometer  of  Poisenille.— This  observer  (1828)  used  a 

U-shaped  tube  partially  filled  with  mercury — a  manometer — which  was  brought  into 
coimection  with  a  blood-vessel  by  means  of  a  rigid  tube.  [The  mercury  oscillated 
with  every  pulsation,  and  the  extent  of  the  oscillations  was  read  off  by  means  of  a 
scale  attached  to  the  bent  tube.     He  called  the  instrument  a  Ticemadynamometer]. 

[(3.)  Vierordt  used  a  tube  five  or  six  feet  long,  and  filled  it  with  a  solution  of 
sodium  carbonate,  thus  preventing  much  blood  from  entering  the  tube,  while 
at  the  same  time  the  soda  solution  prevented  the  coagulation  of  the  blood.] 

(4.)  C.  Ludwig's  Kymograph.— C.  Ludwig  employed  a  U-shaped  mano- 
meter of  the  same  kind,  but  he  placed  a  light  float  (Fig.  72,  d,  s)  upon 
the  surface  of  the  mercury  in  the  open  limb  of  the  tube.  A 
writing-style,  /,  placed  transversely  on  the  free-end  of  the  float, 
inscribed  the  movements  of  the  float — and,  therefore,  of  the  mercury 
— upon  a  cylinder,  c,  caused  to  revolve  at  a  uniform  rate.  This 
apparatus  registered  the  height  of  the  blood-pressure,  as  well  as 
the  pulsatile  and  other  oscillations  occurring  in  the  mercury.  Volk- 
mann called  this  instrument  a  Tcymograph  or  "  wave-writer."  The 
difierence  of  the  height  of  the  column  of  mercury,  c,  d,  in  both  limbs 
of  the  tube  indicates  the  pressure  within  the  vessel.  If  the  height  of 
the  column  of  mercury  be  multiplied  by  13"5,  this  gives  the  height 
of  the  corresponding  column  of  blood.  Setschenow  placed  a  stop-cock 
in  the  lower  bend,  li,  of  the  tube.  If  this  be  closed  so  as  just  to 
permit  a  small  aperture  of  communication  to  remain,  the  pulsatile 
vibrations  no  longer  appear,  and  the  apparatus  indicates  the  raean 
pressure.  By  the  term  r)iean  jJressure  is  meant  the  limit  of  pressure, 
above  and  below  which  the  oscillations  occurring  in  an  ordinary  blood- 


LUDWIG  fi   KYMOGRAPH. 


163 


pressure   tracing  range.      [Briefly,  it  is  the  average  elevation  of  the 
mercurial  column.] 


Fig.  72. 
T,  Scheme  of  C.  Ludwig's  kymograph  ;  II,  Pick's  spring-kymograph. 

In  a  blood-pressure  tracing,  such  as  Fig.  74,  each  of  the  smaller  waves  corre- 
sponds to  a  heart-beat,  the  ascent  corresponding  to  the  systole  and  the  descent  to  the 
diastole.  The  large  undulations  are  due  to  the  respiratory  movements.  It  is  clear 
that  the  heart-beat  is  expressed  as  a  simple  rise  and  fall  (Fig.  74),  so  that  the  curve 
of  the  heart-beat  obtained  with  a  mercurial  kymograph  differs  from  a  sphygmo- 
graphic  curve.  A  perfect  recording  instrument  ought  to  indicate  the  height  of  the 
blood-pressure  and  also  the  size,  form,  and  duration  of  any  wave-motion  com- 
municated to  it.  The  mercurial  manometer  does  not  give  the  true  form  of  the 
pulse-wave,  as  the  mercury,  when  once  set  in  motion,  executes  vibrations  of  its 
own,  owing  to  its  great  inertia,  and  thus  the  finer  movements  of  the  pulse- wave  are 
lost.  Hence  a  mercurial  kymograph  is  used  for  registering  the  blood-pressure,  and 
not  for  obtaining  the  exact  form  of  the  pulse- wave.  Instruments  with  less  inertia 
and  with  no  vibrations  peculiar  to  themselves,  are  required  for  this  purpose.  [The 
theory  of  the  mercurial  manometer  has  been  carefully  worked  out  by  Mach  and 
also  by  v.  Kries.] 

[Method. — Expose  the  carotid  of  a  chloralised  rabbit,  and  isolate  a  portion  of 
the  vessel  between  two  ligatures,  or  two  spring  clamps.  With  a  pair  of  scissors 
make  an  oblique  slit  into  the  artery,  and  into  it  insert  a  straight  glass  cannula, 
directing  the  open  end  of  the  cannula  towards  the  heart.  FUl  the  cannula 
^vith  a  saturated  solution  of  sodium  carbonate,  taking  care  that  no  air-bubbles 
enter,  and  connect  it  with  the  lead  tube  which  goes  to  the  descending  limb 
of  the  manometer.  The  tube  which  connects  the  artery  with  the  manometer  must 
be  flexible  and  yet  inelastic,  and  a  lead  tube  is  best.  It  is  usual  to  connect  a 
pressure-bottle,  containing  a  saturated  solution  of  sodium  carbonate,  by  means  of  an 
elastic  tube,  with  the  tube  attached  to  the  manometer.  This  bottle  can  be  raised 
or  lowered.  Before  begiiming  the  experiment,  raise  the  pressure-bottle  until  there 
is  a  -positive  pressure  of  several  inches  of  mercury  in  the  manometer,  or  until  the 
pressure  is  about  equal  to  the  estimated  blood-pressure,  and  then  clamp  the  tube 


164 


SPRING-KYMOGRAPH. 


of  the  pressure-bottle  where  it  joins  the  lead  tube.  By  having  this  positive 
pressure,  the  escape  of  blood  from  the  artery  into  the  solution  of  sodium  carbonate 
is  to  a  large  extent  avoided.     When  all  is  readj^  the  ligature  on  the  cardiac  side 

of  the  cannula  is  removed,  and 
immediately  the  float  begins  to 
oscillate  and  inscribe  its  move- 
ments upon  the  recording  sur- 
face. The  fluid  within  the 
artery  exerts  pressure  laterally 
upon  the  sodium  carbonate 
solution,  and  this  in  turn  trans- 
mits it  to  the  mercury.] 

[When  we  have  occasion  to 
take  a  tracing  for  any  length 
of  time,  it  must  be  written 
upon  a  strip  of  paper  which 
is  moved  at  a  uniform  rate 
in  front  of  the  writing- 
style  on  the  float  (Fig.  73). 
Various  arrangements  are  em- 
ployed for  this  purpose,  but  it 
is  usual  to  cause  a  cylinder  to 
revolve  so  as  to  unfold  a  roll  or 
riband  of  paper  placed  on  a 
movable  bobbin.  As  the  cylin- 
der revolves,  it  gradually  winds 
off  the  strip  of  paper,  which  is 
kept  applied  to  the  revolving 
surface  by  ivory  friction  wheels. 
In  Fick's  complicated  kymo- 
graph a  long  strip  of  smoked 
paper  is  used.  The  writing- 
style  may  consist  of  a  sable 
brush,  or  a  fine  glass  pen  filled 
with  aniline  blue  dissolved  in 
water,  to  which  a  little  alcohol 
and  glycerine  are  added.] 

[In  order  to  measure  the 
height  of  the  pressure,  we 
must  know  the  position  of  the 
abscissa  or  line  of  no  pressure,  and  it  may  be  recorded  at  the  same  time  as  the 
blood-pressure  or  afterwards.  ] 

[In  Fig.  74,  0  -  ce  is  the  zero-line  or  the  abscissa,  and  the  height  of  the  vertical 
lines  or  ordinates  may  be  measured  by  the  millimetre  scale  on  the  left  of  the 
figure.  The  height  of  the  blood-pressure  is  obtained  by  drawing  ordinates  from 
the  curve  to  the  abscissa,  measuring  their  length,  and  rmdtiplying  by  Uvo.'] 

(5.)  Spring-Kymograph.— A.  Fick  (1864)  constructed  a  "  spring-kymo- 
graph" on  the  principle  of  Bourdon's  manometer  (Fig.  72,  II). 

A  hollow  C-shaped  metallic  spring,  F,  is  filled  with  alcohol.  One  end  of  the 
hollow  spring  is  closed,  and  the  other  end,  covered  by  a  membrane,  is  brought  into 
connection  with  a  blood-vessel  by  a  junction-piece  filled  with  a  solution  of  sodium 
carbonate.  As  soon  as  the  communication  with  the  artery  is  opened,  the  pressure 
rises,  and  the  spring,  of  course,   tends  to  straighten  itself.    To  the  closed  end,  &, 


Fig.  73. 
Ludwig's  improved  form  of  revolving  cylinder,  R, 
which  is  moved  by  the  clock-work. in  the  box, 
A,  and  regulated  by  a  Foucault's  regulator 
placed  on  the  top  of  the  box.  The 
disc,  D,  moved  by  the  clock-work,  presses 
upon  the  two  wheels,  n,  which  can  be  raised 
or  lowered  by  the  screw,  L,  thus  altering  the 
position  of  n  on  D,  so  as  to  cause  the 
cylinder  to  rotate  at  different  rates.  The 
cylinder  itself  can  be  raised  by  the  handle,  v. 
On  the  left  side  of  the  figure  is  a  mercurial 
manometer.  When  the  cylinder  is  used,  it  is 
covered  with  smoked  smooth  paper. 


ESTIMATION   OF  THE  BLOOD-PRESSURE  IN   MAN.  165 

there  is  fixed  a  vertical  rod  attached  to  a  series  of  levers,  A,  i,  k,  e,  one  of  which 
writes  its  movements  upon  a  surface  moving  at  a  uniform  rate.  The  blood-pressure 
and  the  periodic  variations  of  the  pulse  are  both  recorded,  although  the  latter  is 
not  done  with  absolute  accuracy. 


Fi-.  74. 

Blood-pressure  curve  of  the  carotid  of  a  dog  obtained  with  a  mercurial  manometer, 
0  -  a;  =  line  of  no  pressure,  zero  line,  or  abscissa ;  y-y'  is  the  blood -pressure 
tracing  with  small  waves,  each  one  caused  by  a  heart-beat,  and  the  large 
waves  due  to  the  respiration.  A  millimetre  scale  shows  the  height  of  the 
pressure  in  millimetres  of  mercury. 

[Hering  improved  Fick's  instrument  (Fig.  75).  a,  b,  c,  is  the  hollow  spring  filled 
with  alcohol,  and  communicating  at  a  with  the  lead  tube,  d,  passing  to  the  cannula 
in  the  artery.  To  c  is  attached  a  series  of  light  wooden  levers  with  a  writing- 
style,  s.  The  lower  part  of  4  dips  into  a  vessel,  e,  filled  with  oil  or  glycerine  which 
serves  to  damp  the  vibrations  of  the  levers.  At  /  is  a  syringe  communicating 
with  the  tube,  d,  filled  with  solution  of  sodic  carbonate,  and  used  for  regulating 
the  amount  of  fluid  in  the  tube  connecting  the  manometer  with  the  blood-vessel. 
The  whole  apparatus  can  be  raised  or  lowered  on  the  toothed  rod,  /(,  by  means  of 
the  millhead  opposite,  g,  to  which  all  the  parts  of  the  apparatus  are  attached.] 

(B.)  In  Man  the  blood-pressure  may  be  estimated  by  means  of  a 
properly  graduated  sphjgmograph  (p.  130).  The  pressure  required  to 
abolish  the  movement  of  the  lever  indicates  approximately  the  vascular 
tension.  Landois  (Schobel)  investigated  the  radial  pulse  in  a  healthy 
student,  and  obtained  a  mean  blood-pressure  equal  to  550  grammes. 

(2.)  By  a  manometric  method  v.  Basch  estimated  the  blood-pres- 


166 


BLOOD-PRESSURE  IN  THE  ARTERIES. 


sure.  He  placed  a  capsule  containing  fluid  upon  a  pulsating  artery,  and 
the  capsule  communicated  with  a  mercurial  manometer.  As  soon  as 
the  pressure  within  the  manometer  slightly  exceeded  that  within  the 

artery,  the  artery  was 
compressed  so  that  a 
sphygmograph  placed 
on  a  peripheral  por- 
tion of  the  vessel 
ceased  to  beat.  Both 
arrangements,  how- 
ever, do  not  give  the 
exact  pressure  within 
the  artery,  they  only 
indicate  the  pressure 
which  is  required  to 
compress  the  artery 
and  the  overlying  soft 
parts.  The  pressure 
required  to  compress 
the  arterial  walls,  how- 
ever, is  very  small 
compared  with  the 
blood-pressure.  It  is 
only  4  mm.  Hg.  v.  Basch  estimated  the  pressure  in  the  radial  artery 
of  a  healthy  man  to  be  135-165  millimetres  of  mercury. 

In  children  the  blood-pressure  increases  with  age,  height,  and  weight.  In  the 
superticial  temporal  artery  from  2-3  years,  it  is  =  97  mm. ;  from  12-13  years,  113 
mm.  Hg.  (A.  Eckert,  c.  §  100).  The  blood-pressure  is  raised  immediately  after 
bodily  movements  ;  it  is  higher  when  a  person  is  in  the  horizontal  position  than 
when  sitting,  and  in  sitting  than  in  standing  (Eriedmann).  After  a  cold  as  well 
as  after  a  warm  bath  (L.  Lehmann),  the  first  effect  is  an  increase  of  blood- 
pressure  and  of  the  quantity  of  urine  (Grefberg). 


Fig.  75. 
Fick's  Spring-manometer,  as  improved  by  Hering. 


85.  Blood-Pressure  in  the  Arteries. 

The  following  results  have  been  obtained  by  experiment  on  systemic 
arteries : — 

{a.)  Mean  Blood-Pressure.— The  blood-pressure  is  very  considerable, 
varying  within  pretty  wide  limits;  in  the  large  arteries  of  large 
mammals,  and  perhaps  in  man  it  is  =  140  -  160  miUimetres  (5-4  to  6-4 
inches)  of  a  mercurial  column. 

The  following  results  have  been  obtained,  those  marked  thus  *  by  Poiseuille, 
and  those  +  by  Volkmann  :— 


BLOOD-PRESSURE  IN  THE  ARTERIES. 


167 


*  Carotid,  Horse,  161  mm. 


+  Aorta  of  frog,  22-29  mm. 

+  Gill  artery  of  Pike,  35-84:  mm. 

Brachial  artery  of  man  during   an 

operation,  110-120  mm.  (Faivre). 

Perhaps    too  low    owing    to    the 

injury. 


„       122-214  mm. 
Dog,  151  mm. 

,,     130- 190  mm.  (Ludwig) 
+     ,,         (ioa,t,  118-135  mm. 
+     ,,         Rabbit,  90  mm. 
+     „        Fowl,  88-171  mm. 

The  pressure  in  the  aorta  of  mammals  varies  from  200  to  250  mm.  Hg.   • 

As  a  general  rule,  the  blood-pressure  in  large  animals  is  higher  than 
in  small  animals,  because  in  the  former  the  blood-channel  is  consider- 
ably longer,  and  there  is  greater  resistance  to  be  overcome.  In  very 
young  and  in  very  old  animals  the  pressure  is  lower  than  in  individuals 
in  the  prime  of  life. 

(b.)  Branching  of  the  Blood- Vessels. — Within  the  large  arteries  the 
blood-pressure  diminishes  relatively  little  as  we  pass  towards  the 
periphery,  because  the  difference  of  the  resistance  in  the  different 
sections  of  large  tubes  is  very  small.  As  soon,  however,  as  the 
arteries  begin  to  divide  frequently,  and  undergo  a  considerable  diminu- 
tion in  their  lumen,  the  blood-pressure  in  them  rapidly  diminishes, 
because  the  propelling  energy  of  the  blood  is  much  weakened  owing 
to  the  resistance  which  it  has  to  overcome  (p.  118). 

(c.)  Amount  of  Blood. — The  blood-pressure  is  increased  with  greater 
filling  of  the  arteries,  and  vice  versa, ;  it 


Increases 

1.  With     increased     and     accelerated 

action  of  the  heart; 

2.  In  plethoric  persons; 

3.  After    increase  of   the   quantity   of 

blood  by  direct  transfusiou,  or 
after  a  copious  meal. 


Decreases 

1.  During    dmiinished    and    enfeebled 

action  of  the  heart; 

2.  In  anajmic  persons; 

3.  After  haemorrhage  or  considerable  ex- 

cretions from  the  blood  by  sweat- 
ing, the  urine,  severe  diarrhoea. 


The  blood-pressure  does  not  vary  in  the  same  proportion  as  the  variations  in  the 
amount  of  blood.  The  vascular  system,  in  virtue  of  its  muscular  tissue,  has  the 
property,  within  liberally  wide  limits,  of  accommodating  itself  to  larger  or  smaller 
quantities  of  blood  (C,  Ludwig  and  Worm  Miiller,  §  102,  d).  Small  and  moderate 
hemorrhages  (in  the  dog  to  2 '8  per  cent  of  the  body- weight)  have  no  obvious  effect 
on  the  blood-pressm-e.  After  a  slight  loss  of  blood  the  pressure  may  even  rise  (Worm 
MiiUer).  If  a  large  amount  of  blood  be  -withdrawn,  it  causes  a  great  fall  of  the 
blood-pressure  (Hales,  Magendie),  and  when  haemorrhage  occurs  to  4-6  per  cent, 
of  the  body- weight,  the  blood-pressure =0.  The  transfusion  of  a  moderate  amount 
of  blood  does  not  raise  the  mean  arterial  blood-pressure.  [There  are  important 
practical  deductions  from  these  experiments,  viz.,  that  the  blood-pressure  cannot 
be  diminished  directly  by  moderate  blood-letting,  and  that  the  blood-pressure  is 
not  necessarily  high  in  plethoric  persons.] 

{d.)  Capacity  of  the  Vessels. — The  arterial  pressure  rises  when  the 
capacity  of  the  arterial  system  is  diminished,  and  conversely.  The 
plain  circularly-disposed  muscular  fibres  of  the  arteries  are  the  chief 


168 


BLOOD-PRESSUEE  IN   THE  ARTERIES. 


agents  concerned  in  this  process.  When  they  relax,  the  arterial  blood- 
pressure  falls,  and  when  they  contract,  it  rises.  These  actions  of 
muscular  fibres  are  controlled  and  regulated  by  the  action  of  the  vaso- 
motor nerves  (vol.  ii.) 

(e.)  Collateral  Vessels. — The  arterial  pressure  within  a  given  area  of 
the  vascular  system  must  rise  or  fall  according  as  the  neighbouring 
areas  are  diminished,  whether  by  the  application  of  pressure,  or  a 
ligature,  or  are  rendered  impervious,  or  as  these  areas  dilate. 
The  application  of  cold  or  warmth  to  limited  areas  of  the  body- 
increasing  or  diminishing  the  atmospheric  pressure  on  a  part — the 
paralysis  or  stimulation  of  certain  vaso-motor  areas  (vol.  ii.),  all  pro- 
duce remarkable  variations  in  the  blood-pressure.  [The  effect  of 
dilatation  of  a  large  vascular  area  on  the  arterial  pressure  is  well 
shown  by  what  happens  when  the  blood-vessels  of  the  abdomen  are 
dilated.  If  the  central  end  of  the  superior  cardiac  nerve  of  a  rabbit  be 
stimulated,  after  a  few  seconds  the  blood-vessels  of  the  abdomen  dilate, 
and  gradually  there  is  a  steady  fall  of  the  blood-pressure  in  the 
systemic  arteries.  Fig.  76  is  a  blood-pressure  tracing  showing  the 
height  of  the  blood-pressure  before  stimulation,  a.  The  stimulation 
was  continued  from  a  to  h,  and  after  a  certain  latent  period,  there  is 
a  steady  fall  of  the  blood-pressure.     The  nerve  which  causes  this  reflex 


Fig.  76. 

Kymographic  tracing  showing  the  effect  on  the  blood-pressure  of  stimulation  of  the  central  end  of  the 
depressor  nerve  in  the  rabbit.     Stimulation  began  at  a,  and  ended  at  b  ;   o—x,  the  abscissa. 


RESPIRATORY  UNDULATIONS  IN  THE  BLOOD-PRESSURE  CURVE.    169 

dilatation  of  the  abdominal  blood-vessels,  and  consequent  lowering  of 
the  blood-pressure,  is  also  called  the  depressor  nerve. 

(/.)  Respiratory  Undulations. — The  arterial  pressure  also  undergoes 
regular  variations  or  undulations  owing  to  the  respiratory  movements. 
These  undulations  are  called  respiratory  undulations  (Figs.  74  and 
77).  Stated  broadly,  during  every  strong  inspiration  the  pressure 
rises,  and  during  expiration  it  falls  (§74).  This  is  not  quite  correct — 
(see  below).  These  undulations  may  be  explained  by  the  fact,  that 
with  every  expiration,  the  blood  in  the  aorta  is  subjected  to  an  increase 
of  pressure  through  the  compressed  air  in  the  chest ;  with  every 
inspiration,  on  the  other  hand,  it  is  diminished  owing  to  the  diminu- 
tion of  the  air  in  the  lungs  acting  upon  the  aorta.  Besides,  the 
inspiratory  movements  of  the  chest  aspirate  blood  from  the  vense 
cavse  towards  the  heart,  while  expiration  retards  it,  and  thus  influences 
the  blood-pressure.  The  undulations  are  most  marked  in  the  arteries 
lying  nearest  to  the  heart.  The  respiratory  undulations  are  due  in  part 
to  a  stimulation  or  condition  of  excitement  of  the  vaso-motor  centre, 
which  runs  parallel  with  the  respiratory  movements.  This  stimulation 
of  the  vaso-motor  centre  causes  the  arteries  to  contract,  and  thus  the 
blood-pressure  is  raised.  The  variations  in  the  pressure  which  depend 
upon  a  varying  activity  of  the  vaso-motor  centre  are  known  as  the 
curves  of  Traube  and  Hering  (p.  171).  In  Fig.  77  are  represented  a 
blood-pressure  tracing  and  a  curve  of  the  movements  of  respiration 
(thick  line)  taken  simultaneously  in  a  dog  by  C.  Ludwig  and  Einbrodt. 
The  blood-pressure  tracing  was  obtained  from  the  carotid  artery,  while 


Fig.  77. 

Kymogi'aphic  blood-pressure  tracing  (upper,  thin  line),  and  respiration  curve 
(lower,  thick  line),  taken  simultaneously — ex,  expiration  ;  in,  inspiration  ;  c,  c, 
heart-beats.  The  large  curves  in  the  blood-pressure  tracing  are  due  to 
respiration  (Ludwig  and  Einbrodt). 

the  pressure  within  the  thorax  was  measured  by  means  of  a  manometer 
placed  in  connection  with  one  pleural  cavity.  In  this  curve,  when 
expiration  begins  (at  ex),  and  as  the  expiratory-pressure  rises,  the  blood- 
pressure  rises,  while  when  inspiration  begins  (at  in)  both  fall.  The 
blood-curve,    however,  begins   to   rise  (at  c)  before  expiration   com- 


170    RESPIRATORY  UNDULATIONS  IN  THE  BLOOD-PRESSURE  CURVE. 

mences — i.e.,  during  the  last  part  of  the  act  of  inspiration.  This 
is  due  to  the  contraction  of  the  arteries,  caused  by  impulses  sent 
from  the  vaso-motor  centre.  It  is  also  aided  by  the  circum- 
stance that  during  inspiration  there  is  an  increased  inflow  of 
venous  blood  to  the  heart,  so  that  when  it  contracts,  more  blood  is 
forced  into  the  arteries.  [The  maxima  and  minima  of  the  two  curves 
do  not  coincide  exactly,  but  in  addition  the  number  of  pulse-beats  is 
greater  in  the  ascent  than  in  the  descent.  This  is  well-marked 
in  a  blood-pressure  tracing  from  a  dog's  carotid,  while  in  a 
rabbit  this  difference  of  the  pulse-rate  is  but  slightly  marked.  The  ■ 
smaller  number  of  pulse-beats  during  the  descent — i.e.,  during  the 
greater  part  of  expiration — is  due  to  the  activity  of  the  cardio- 
inhibitory  centre  in  the  medulla  oblongata.  This  is  proved  by  the  fact, 
that  section  of  both  vagi  in  the  dog  causes  the  difference  of  pulse-rate 
to  disappear,  while  other  conditions  remain  the  same  as  before,  except 
that  the  heart  beats  more  rapidly.  It  would  seem  that  during  the  ascent, 
the  cardio-inhibitory  centre  is  comparatively  inactive.  It  is  clear, 
therefore,  that  the  respiratory  and  cardio-inhibitory  centres  in  the  medulla 
oblongata  act  to  a  certain  extent  in  unison,  so  that  it  is  reasonable  to 
suppose  that  other  centres  situated  in  close  proximity  to  these  may 
also  act  in  unison  with  them,  or,  as  it  were,  "  in  sympathy."  As 
already  stated,  the  vaso-motor  centre  is  also  in  action  during  a  particular 
part  of  the  time.] 

[If  a  dog  be  curarised  and  artificial  respiration  established,  the 
respiratory  undulations  still  occur,  although  in  a  modified  form.  In 
artificial  respiration,  the  mechanical  conditions,  as  regards  the  intra- 
thoracic pressure,  are  exactly  the  reverse  of  those  which  obtain  during 
ordinary  respiration.  Air  is  forced  into  the  chest  during  artificial 
respiration,  so  that  the  pressure  within  the  chest  is  increased  during 
inspiration,  while  in  ordinary  inspiration  the  pressure  is  diminished. 
Thus,  the  same  mechanical  explanation  will  not  suffice  for  both  cases.] 

If  the  artificial  respiration  be  suddenly  interrupted  in  a  curarised 
animal,  the  blood-pressure  rises  steadily  and  rapidly.  This  rise  is  due 
to  the  stimulation  of  the  vaso-motor  centre  in  the  medulla  oblongata  by 
the  impure  blood.  This  causes  contraction  of  the  small  arteries 
throughout  the  body,  which  retards  the  out-flow  from  the  large 
arteries,  and  thus  the  pressure  within  them  is  raised.  [Stated 
broadly,  the  arterial  pressure  depends  on  the  central  organ — the 
heart,  and  on  the  condition  of  the  peripheral  organs — the  small 
arteries.  Both  are  influenced  by  the  nervous  system.  If  the  action  of 
the  vaso-motor  centre  be  eliminated  by  dividing  the  spinal  cord  in  the 
cervical  region,  arrest  of  the  respiration  causes  a  very  slight  rise  of  the 
blood-pressure ;  hence,  it  is  evident  that  venous  blood  acts  but  slightly 


TRAUBE-HERING  CURVES.  171 

on  the  heart,  or  on  any  local  peripheral  nervous  mechanism,  or  on  the 
muscular  fibres  of  the  arteries.  This  experiment  shows  that  it  is 
the  vaso-motor  centre  which  is  specially  acted  upon  by  the  venous 
blood.] 

[Traube-Hering  Curves. — The  following  experiment  proves  that  the 
varying  activity  of  the  vaso-motor  centre  suffices  to  produce  undula- 
tions in  the  blood-pressure  tracing.  Take  a  dog,  curarise  it,  expose 
both  vagi  and  establish  artificial  respiration ;  then  estimate  the  blood- 
pressure  in  the  carotid.  After  section  of  the  vagi,  the  heart  will 
continue  to  beat  more  rapidly,  but  it  will  be  undisturbed  by  the 
cardio-inhibitory  centre.  Thus  the  central  factor  in  the  causation  of 
the  blood-pressure  remains  constant.  Suddenly  interrupt  the  respi- 
ration and,  as  already  stated,  the  blood-pressure  will  rise  steadily  and 
uniformly,  owing  to  the  stimulation  of  the  vaso-motor  centre  by  the 
venous  blood.  In  this  case  the  peripheral  factor  or  state  of  tension  of 
the  small  arteries  throughout  the  body  is  influenced  by  the  condition 
of  the  nerve-centre  which  controls  their  action.  After  a  time,  the  blood- 
pressure  tracing  shows  a  series  of  bold  curves  higher  than  the  original 
tracing.  These  can  only  be  due  to  an  alteration  in  the  state  of  the 
small  arteries,  brought  about  by  a  condition  of  rhythmical  activity  of 
the  vaso-motor  centre.  These  curves  were  described  and  figured  by 
Traube,  and  are  called  the  Traube  or  Traube-Hering  curves.  As  in  other 
conditions,  stimulation  gives  place  to  exhaustion,  and  soon  the  venous 
blood  paralyses  the  vaso-motor  centre  and  the  small  arteries  relax, 
blood  flows  freely  out  of  the  larger  arteries,  and  the  blood-pressure 
rapidly  sinks.  Variations  in  the  blood-pressure  have  been  observed 
after  a  mechanical  pump  has  been  substituted  for  the  heart,  i.e.,  after 
all  respiratory  movements  have  been  set  aside,  so  that  the  only  factor 
which  would  account  for  the  phenomena  of  the  Traube-Hering  curves 
is  the  variation  in  the  peripheral  resistance  in  the  small  arteries, 
determined  by  the  condition  of  the  vaso-motor  centre.] 

The  respiratory  undulations  of  the  blood-pressure  become  more  pronounced  the 
greater  the  force  of  the  respirations,  which  produce  greater  vai-iations  of  the  intra- 
thoracic pressure.  In  man,  the  diminution  of  the  pressure  within  the  trachea  is 
1  mm.  Hg.  during  tranquil  inspiration,  while  during  forced  respiration,  when  the 
respiratory  passage  is  closed,  it  may  be  57  mm.  Conversely,  during  ordinary 
expiration,  the  j)ressure  is  increased  within  the  trachea  2-3  mm.  Hg.,  while  during 
forced  expiration,  owing  to  the  compression  of  the  abdominal  muscles,  it  may  reach 
87  mm.  Hg. 

The  increase  of  the  blood-pressure  during  inspiration,  as  well  as  the 
fall  during  expiration,  must  in  part  depend  upon  the  pressure  within 
the  abdomen.  As  the  diaphragm  descends  during  inspiration,  it 
presses  upon  the  abdominal  contents,  including  the  abdominal  vessels, 


172  VARIATIONS  OF  THE  BLOOD-PRESSURE. 

whereby  the  blood-pressure  must  be  increased.  The  reverse  effect 
occurs  during  expiration  (Schweinburg).  [Section  of  both  phrenic 
nerves  and  opening  of  the  abdominal  cavity  cause  the  respiratory 
undulations  almost  entirely  to  disappear.  The  respiratory  undulations, 
therefore,  depend  in  great  part  upon  the  changes  of  the  abdominal 
pressure  and  the  effect  of  these  changes  on  the  amount  of  blood  in  the 
abdominal  vessels.  When  making  a  blood-pressure  experiment,  pres- , 
sure  upon  the  abdomen  of  the  animal  with  the  hand,  causes  the 
blood-pressure  to  rise  rapidly.] 

{g)  Variations  with  each  Pulse-beat. — The  mean  arterial  pressure 
undergoes  a  variation  with  each  heart-beat  or  pulse-heat,  causing  the  so- 
called  j^wZsa^or^  undulations  (Fig.  77,  c).  The  mass  of  blood  forced  into 
the  arteries  with  each  ventricular  systole  causes  a  positive  wave  and  an 
increase  of  the  pressure  corresponding  with  it,  which  of  course  corre- 
sponds in  its  development  and  in  its  form  with  the  pulse-curve. 

In  the  large  arteries  Volkmann  found  the  increase  during  the  heart-beat  to  be 
=  x\  (horse)  and  -^^  (dog)  of  the  total  pressure. 

None  of  the  apparatus  described  in  §  84  gives  an  exact  representation  of  the  pulse- 
curve.  They  all  show  simply  a  rise  and  faU,  a  simple  curve.  The  sphygmograph 
alone  gives  a  true  expression  of  the  undulations  in  the  blood-presaure  which  are 
due  to  the  heart-beat. 

{h.)  If  the  heart's  action  be  arrested  or  interrupted  by  continued 
stimulation  of  the  vagus  (Brunner,  1855),  or  by  a  high  positive 
respiratory-pressure  (Einbrodt),  the  arterial  blood-pressure  falls  enor- 
mously, while  it  rises  in  the  veins  as  the  blood  flows  into  them 
from  the  arteries  to  equilibrate  the  difference  of  pressure  in  the  two 
sets  of  vessels.  This  experiment  shows,  that  even  when  the  diflFerence 
of  pressure  is  almost  entirely  set  aside,  the  passive  blood  presses  upon 
the  arterial  walls — i.e.,  on  account  of  the  overfilling  of  the  blood- 
vessels, a  slight  pressure  is  exerted  upon  the  walls,  even  when  there 
is  no  circulation  (Brunner).  [As  already  stated,  the  arterial  pressure 
depends  on  the  condition  of  the  central  organ — the  heart — and  on  the 
peripheral  organs — the  small  arteries.  If  the  action  of  the  heart  be 
arrested,  then  the  blood-pressure  rapidly  falls.  Fig.  78  shows  the 
effect  on  the  blood-pressure,  of  arresting  the  action  of  the  heart,  by 
stimulation  of  the  peripheral  end  of  the  vagus.  There  is  a  sudden 
fall  of  the  arterial  pressure,  as  shown  by  the  rapid  fall  of  the  curve 
from  a]. 

For  the  effects  of  the  nervous  system  upon  the  blood-pressure,  see  ' '  Vaso-motor 
Centre"  (vol.  ii.) 

Pathological. — In  persons  suffering  from  granular  or  contracted  kidney  and 
sclerosis  of  the  arteries,  in  lead  poisoning,  and  after  the  injection  of  ergotin,  which 
causea  contraction  of  the  small  arteries,  it  is  found,  on  employing  the  method  of 


BLOOD-PRESSURE   IN   THE   CAPILLARIES.  173 

V.  Bascb,  that  the  blood-pressure  is  raised.     It  is  also  increased  in  cases  of  cardiac 
hypertrophy  with  dilatation,  and  by  digitalis  in  cardiac  affections,  while  it  falls 


Fig.  78. 

Blood -pressure  tracing  taken  with  a  mercurial  kymograph  from  the  carotid  of  a 
rabbit ;  o-x,  abscissa ;  vagus  nerve  stimulated  between  the  vertical  lines, 
a  and  b. 

after  the  injection  of  morphia  (Kristeller).  The  blood-pressure  falls  in  fever 
(Wetzel),  a  fact  also  indicated  in  the  sphygmogram  (§  69),  la  chlorosis  and 
phthisis  the  blood-pressure  is  low  (Waldenburg). 


SQ.  Blood-Pressure  in  the  Capillaries. 

Methods. — Direct  estimation  of  the  capillary  pressure  is  not  possible  on  account 
of  the  smallness  of  the  capillary  tubes.  If  a  glass  plate  of  known  dimensions  be 
placed  on  a  portion  of  the  skin  rich  in  blood-vessels,  and  if  it  be  weighted  until  the 
capillaries  become  pale,  we  obtain  approximately  the  pressure  necessary  to  over- 
come the  capillary  pressure.  N.  v.  Kries  placed  a  small  glass  plate  (Figs.  79,  80) 
2 "5  -  5  sq.  mm.,  on  a  suitable  part  of  the  skin,  e.g. ,  the  skin  at  the  root  of  the  nail  on 
the  terminal  phalanx,  or  on  the  ear  in  man,  and  on  the  gum  in  rabbits.  Into  a  scale- 
pan  attached  to  this,  weights  were  placed  until  the  skin  became  pale.  The  pressure 
in  the  capillaries  of  the  hand,  when  the  hand  is  raised,  Kries  found  to  be  24  mm. 
Hg. ;  when  the  hand  hangs  down,  54  mm.  Hg. :  in  the  ear,  20  mm. ,  and  in  the  gum 
of  a  rabbit,  32  mm, 

[Roy  and  Graham  Brown  ascertained  the  hydrostatic  pressure  necessary  to  occlude 
the  vessels  in  transparent  parts  placed  under  the  microscope,  e.g.,  the  web  of  a 
frog's  foot,  tongue  or  mesentery  of  a  frog,  the  tails  of  newts  and  small  fishes.  The 
upper  surface  of  the  part  to  be  investigated,  e.g.,  the  web  of  a  frog's  foot,  is  made  just 
to  touch  a  thin  glass  plate.     The  under  surface  is  in  contact  with  a  delicate  trans- 


174  CONDITIONS  AFFECTING   CAPILLARY  PRESSURE. 

parent  membrane  covering  the  upper  end  of  a  small  brass  cylinder,  whose  lower 
end  contains  a  piece  of  glass  fitted  air-tight  into  it.  The  interior  of  the  brass 
cylinder  communicates  by  means  of  a  tube  with  an  arrangement  for  obtaining  any 
desired  pressure,  and  the  amount  of  the  pressure  is  indicated  by  a  manometer. 
Air  pressure  is  used,  and  this  is  obtained  by  compressing  a  caoutchouc  bag  between 
two  brass  plates.     The  membrane  to  be  investigated  lies  between  two  transparent 


Fig.  79. 

Apparatus  used  by  v.  Kries  for  estimating  the  capillary  pressure — a,  the  small 
square  of  glass.  In  Fig.  79  the  scale-pan  for  the  weights  is  below,  and  in 
Fig.  80,  above. 

media,  an  upper  one  of  glass  and  a  lower  one  of  transparent  membrane,  on  which 
the  pressure  acts.  Any  change  in  the  vessels  is  observable  by  means  of  the  micro- 
scope. These  observers  conclude  from  their  experiments  that  the  capillaries  are 
contractile,  and  that  their  contractility  is,  to  aU  appearance,  in  constant  action. 
The  regulation  of  the  peripheral  blood-stream  is  due  not  only  to  the  cerebro-spinal 
vaso-motor  centres,  but  also  to  independent  peripheral  vaso-motor  mechanisms, 
which  may  be  nervous  in  their  nature,  or  are  due  to  some  direct  action  on  the  walls 
of  the  vessels  (p.  126).] 

Conditions  influencing  Capillary  Pressure. — The  intra-capillary  blood- 
pressure  in  a  given  area  increases — (1.)  When  the  afferent  small 
arteries  dilate.  When  they  are  dilated  the  blood-pressure  within  the 
large  arteries  is  propagated  more  easily  into  them.  (2.)  By  increasing 
the  pressure  in  the  small  afferent  arteries.  (3.)  By  narrowing  the 
diameter  of  the  veins  leading  from  the  capillary  area.  Closure  of  the 
veins  may  quadruple  the  pressure  (v.  Kries).  (4.)  By  increasing  the 
pressure  in  the  veins  (e.g.,  by  altering  the  position  of  a  limb).  A 
diminution  of  the  capillary  pressure  is  caused  by  the  opposite 
conditions.  ^ 

Changes  in  the  diameter  of  the  capillaries  influence  the  internal  pressure.  We 
have  to  consider  the  movements  of  the  capUlary  wall  itself  (protoplasma-movements, 
Strieker — p.  125),  as  well  as  the  pressure,  swelling,  and  consistence  of  the  surround- 


BLOOD-PRESSURE  IN  THE  VEINS.  175 

ing  tissues.  The  resistance  to  the  blood-stream  is  greatest  in  the  capillary  area, 
and  it  is  evident  that  the  blood  in  a  long  capillary  mvist  exert  more  pressure  at  the 
commencement  than  cit  the  end  of  the  capillary;  in  the  middle  of  the  capillary  area 
the  blood-pressure  is  just  about  one-half  of  the  pressure  within  the  large  arteries 
(Bonders).  The  capillary  pressure  must  also  vary  in  different  regions  of  the  body. 
Thus,  the  pressure  within  the  intestinal  capillaries,  in  those  constituting  the 
glomeruli  of  the  kidney,  and  in  those  of  lower  limbs  when  the  person  is  in  the  erect 
posture,  must  be  greater  than  in  other  regions,  depending  in  the  former  cases  partly 
upon  the  double  resistance  caused  by  two  sets  of  capillaries,  and  in  the  latter  case 
partly  on  purely  hydrostatic  causes. 


87.  Blood-Pressure  in  the  Veins. 

In  the  large  venous  trunks  near  the  heart  (innominate,  sub-clavian, 
jugular)  a  mean  negative  pressv/re  of  about  -  0"1  mm.  Hg.  prevails  (H. 
Jacobson).  Hence,  the  lymph-stream  can  flow  unhindered.  As  the 
distance  of  the  veins  from  the  heart  increases,  there  is  a  gradual  increase 
of  the  lateral  pressure ;  in  the  external  facial  vein  (sheep)  =  +  3  mm. ; 
brachial,  4"1  mm.,  and  in  its  branches  9  mm.;  crural,  11' 4  mm. 
(Jacobson).  [The  pressure  is  said  to  be  negative  when  it  is  less  than 
that  of  the  atmosphere.] 

Conditions  Influencing  the  Venous  Pressure. — (1.)  All  conditions 
which  diminish  the  difference  of  pressure  between  the  arterial  and 
venous  systems  increase  the  venous  pressure  and  vice  versd. 

(2.)  General  plethora  of  blood  increases  it ;  anaemia  diminishes  it. 

(3).  Respiration,  or  the  aspiration  of  the  thorax,  affects  specially  the 
pressure  in  the  veins  near  the  heart ;  during  inspiration,  owing  to  the 
diminished  tension,  blood  flows  towards  the  chest,  while  during  expira- 
tion it  is  retarded.  The  effects  are  greater  the  deeper  the  respiratory 
movements,  and  these  may  be  very  great  when  the  respiratory  passages 
are  closed  (§  60). 

[When  a  vein  is  exposed  at  the  root  of  the  neck,  it  collapses  during  inspiration, 
and  fills  during  expiration— a  fact  which  was  known  to  Valsalva.  The  respiratory 
movements  do  not  affect  the  venous  stream  in  the  peripheral  veins.  The  veins  of 
the  neck  and  face  become  distended  with  blood  during  crying,  and  on  making 
violent  expiratory  efforts,  as  in  blowing  upon  a  wind-instrument ;  while  every 
surgeon  is  well  acquainted  with  the  fact  that  air  is  particularly  apt  to  be  sucked 
into  the  veins,  especially  in  operations  near  the  root  of  the  neck.  This  is  due  to 
the  negative  intra-thoracic  pressure  occurring  during  inspiration.] 

(4.)  Aspiration  of  the  Heart. — Blood  is  sucked  or  aspirated  into 
the  auricles  when  they  dilate,  so  that  there  is  a  double  aspiration — 
one  synchronous  with  inspiration,  and  the  other,  which  is  but 
slight,  synchronous  with  the  heart-beat.  There  is  a  corresponding 
retardation  of  the  blood-stream  in  the  venae  cavse,  caused  by  the 
contraction  of  the  auricle  (see  p.  77,  a).     The  respiratory  and  cardiac 


176  BLOOD-PRESSURE  IN  THE   VEINS. 

undulations  are  occasionally  observable  in  the  jugular  vein  of  a  healthy 
person  (§  99). 

[Braune  showed  that  the  femoral  vein  under  Poupart's  ligament  collapsed  when 
the  lower  limb  was  rotated  outwards'  and  backwards,  but  filled  again  when  the 
limb  was  restored  to  its  former  position.  All  the  veins  which  open  into  the 
femoral  vein  have  valves,  which  permit  blood  to  pass  into  the  femoral  vein,  but 
prevent  its  reflux.  This  mechanism  acts  to  a  slight  degree  as  a  kind  of  suction 
and  pressure  apparatus  when  a  person  walks,  and  thus  favours  the  onward  move- 
ment of  the  blood,] 

(5.)  Changes  in  the  position  of  the  limbs  or  of  the  body,  for  hydro- 
static reasons,  greatly  alter  the  venous  pressure.  The  veins  ol  the 
lower  extremity  bear  the  greatest  pressure,  while  at  the  same  time 
they  contain  most  muscle  (K.  Bardeleben,  §  65).  Hence,  when 
these  muscles  from  any  cause  become  insufficient,  dilatations  occur  in 
the  veins,  giving  rise  to  the  production  of  varicose  veins. 

[(6.)  Movements  of  the  Voluntary  Muscles, — Veins  which  lie  between 
muscles  are  compressed  when  these  muscles  contract,  and  as  valves 
exist  in  the  veins  the  flow  of  the  blood  is  accelerated  towards  the 
heart;  if  the  outflow  of  the  blood  be  obstructed  in  any  way,  then 
the  venous  pressure  on  the  distal  side  of  the  obstruction  may  be 
greatly  increased.  When  a  fillet  is  tied  on  the  upper-arm,  and  the 
person  moves  the  muscles  of  the  fore-arm,  the  course  of  the  superficial 
veins  can  be  distinctly  traced  on  the  surface  of  the  limb.] 

[(7.)  Gh'avity  exercises  a  greater  effect  upon  the  blood-stream  in  the 
extensile  veins  than  upon  the  stream  in  the  arteries.  It  acts  on  the  dis- 
tribution of  the  blood,  and  thus  indirectly  on  the  motion  of  the  blood- 
stream. It  favours  the  emptying  of  descending  veins,  and  retards  the 
emptying  of  ascending  veins,  so  that  the  pressure  becomes  less  in  the 
former  and  greater  in  the  latter.  If  the  position  of  the  limb  be 
changed,  the  conditions  of  pressure  are  also  altered  (Paschutin).  If  a 
person  be  suspended  with  the  head  hanging  downwards,  the  face  soon 
becomes  turgid,  the  position  of  the  body  favouring  the  inflow  of  blood 
through  the  arteries,  and  retarding  the  outflow  through  the  veins. 
If  the  hand  hangs  down  it  contains  more  blood  in  the  veins  than 
if  it  is  held  for  a  short  time  over  the  head,  when  it  becomes  pale 
and  bloodless.  As  Lister  has  shown,  the  condition  of  the  vessels  in 
the  limb  are  influenced  not  only  by  the  position  of  the  limb,  but  also 
by  the  fact  that  a  nervous  mechanism  is  called  into  play.] 

\JAg2AvLre  of  the  Portal  Vein.— The  pressure  and  other  conditions  vary  in 
particular  veins.  Thus,  if  the  portal  vein  be  ligatured,  there  is  congestion  of  the 
capillaries  and  rootlets  of  the  portal  vein,  and  dilatation  of  all  the  blood-vessels  in 
the  abdomen,  and  gradually  nearly  all  the  blood  of  the  animal  accumulates  within 
its  belly,  so  that,  paradoxical  as  it  may  seem,  an  animal  may  be  bled  into  its  own 
belly.    As  a  consequence  of  sudden  and  complete  ligature  of  this  vein,  the  arterial 


BLOOD-PRESSURE   IN   THE  PULMONARY  ARTERY.  177 

blood-pressure  gradually  and  rapidly  falls,  and  the  animal  dies  very  quickly.  If 
the  ligature  be  removed  before  the  blood-pressure  falls  too  much,  the  auimal  may 
recover. 

Ligature  of  the  Veins  of  a  Limb.— The  effect  of  ligaturing  or  compressing  all 
the  veins  of  a  limb  is  well  seen  in  cases  where  a  bandage  has  been  applied  too 
tightly.  It  leads  to  congestion  and  increase  of  pressure  within  the  veins  and 
capillaries,  increased  transudation  of  fluid  through  the  capillaries,  and  consequent 
oedema  of  the  parts  beyond  the  obstruction.  Ligature  of  one  vem  does  not  always 
produce  cedema,  but  if  several  veins  of  a  limb  be  ligatured,  and  the  vaso-motor 
nerves  be  divided  at  the  same  time,  the  rapid  production  of  cedema  is  ensured. 
In  pathological  cases  the  pressure  of  a  tumour  upon  a  large  vein  may  produce 
similar  results.] 


88.  Blood-Pressure  in  the  Pulmonary  Artery. 

Methods. — (l.)  Direct  estimation  of  the  blood-pressure  in  the  pulmonary  artery 
by  opening  the  chest  was  made  by  C.  Ludwig  and  Beutner  (1850).  Artificial  re- 
spiration was  kept  up,  and  the  manometer  was  placed  in  connection  mth  the  left 
branch  of  the  pulmonary  artery. 

The  circulation  through  the  left  lung  of  cats  and  rabbits  was  thereby  completely 
cut  off,  and  in  dogs  to  a  great  extent  interrupted.  There  was  an  additional  dis- 
turbing element,  viz. ,  the  removal  of  the  elastic  force  of  the  lungs  owing  to  the 
opening  of  the  chest,  whereby  the  venous  blood  no  longer  flows  normally  into  the 
right  heart,  while  the  right  heart  itself  is  under  the  full  pressure  of  the  atmo- 
sphere. The  estimated  pressure  in  the  dog  =  29  6;  in  the  cat  =  17 '6  ;  in  the 
rabbit,  12  mm.  Hg. — i.e.,  in  the  dog  3  times,  the  rabbit  4  times,  and  the  cat  5 
times  less  than  the  carotid  pressure. 

(2.)  Hering  (1850)  experimented  upon  a  calf  with  ectopia  cordis.  He  introduced 
glass  tubes  directly  into  the  heart,  by  pushing  them  through  the  muscular  walls  of 
the  ventricles.  The  blood  rose  to  the  height  of  21  inches  in  the  right  tube,  and 
33  "4  inches  in  the  left. 

(3.)  Chauveau  and  Faivre  (1856)  introduced  a  catheter  through  the  jugular  vein 
into  the  right  ventricle,  and  placed  it  in  connection  with  a  manometer  (p.  87). 

Indirect  measurements  have  been  made  by  comparing  the  relative  thickness  of  the 
walls  of  the  right  and  left  ventricles,  or  the  walls  of  the  pulmonary  artery  and 
aorta,  for  there  must  be  a  relation  between  the  pressure  and  the  thickness  of  the 
muscle  in  the  two  cases. 

Beutner  and  Marey  estimated  the  relation  of  the  pulmonary  artery 
to  the  aortic  presssure  as  1  to  3 ;  Goltz  and  Gaule  as  2  to  5 ;  Tick 
and  Badoud  found  a  pressure  of  60  mm.  in  the  pulmonary  artery  of 
the  dog,  and  in  the  carotid  111  mm.  Hg.  The  blood-pressure  within 
the  pulmonary  artery  of  a  child  is  relatively  higher  than  in  the  adult 
(Beneke). 

The  lungs  within  the  chest  are  kept  in  a  state  of  distension,  owing 
to  the  fact  that  a  negative  pressure  exists  on  their  outer  pleural  surface. 
When  the  glottis  is  open,  the  inner  surface  of  the  lung  and  the  walls 
of  the  capillaries  in  the  pulmonary  air-vesicles  are  exposed  to  the  full 
pressure  of  the  air.  The  heart  and  the  large  blood-vessels  within  the 
chest  are  not  exposed  to  the  full  pressure  of  the  atmosphere,  but  only 

12 


178  BLOOD-PRESSURE  IN  THE  PULMONARY  ARTERY. 

to  the  pressure  which  corresponds  to  the  atmospheric  pressure  minus 
the  pressure  exerted  by  the  elastic  traction  of  the  lungs  (§  60).  The 
trunks  of  the  pulmonary  artery  and  veins  are  subjected  to  the  same 
conditions  of  pressure.  The  elastic  traction  of  the  lungs  is  greater,  the 
more  they  are  distended.  The  blood  of  the  pulmonary  capillaries 
will,  therefore,  tend  to  flow  towards  the  large  blood-vessels.  As 
the  elastic  traction  of  the  lungs  acts  chiefly  on  the  thin-walled 
pulmonary  veins,  while  the  semi-lunar  valves  of  the  pulmonary  artery, 
as  well  as  the  systole  of  the  right  ventricle,  prevent  the  blood  from 
flowing  backwards,  it  follows  that  the  blood  in  the  capillaries  of  the 
lesser  circulation  must  flow  towards  the  pulmonary  veins. 

If  tubes  with  thin  walls  be  placed  in  the  walls  of  an  elastic  disten- 
sible bag,  the  lumen  of  these  tubes  changes  according  to  the  manner  in 
which  the  bag  enclosing  them  is  distended.  If  the  bag  be  directly 
inflated  so  as  to  increase  the  pressure  within  it,  the  lumen  of  the  tubes 
is  diminished  (Funke  and  Latschenberger).  If  the  bag  be  placed 
within  a  closed  space,  and  the  tension  within  this  space  be  diminished 
so  that  the  bag  thereby  becomes  distended,  the  tubes  in  its  wall 
dilate.  In  the  latter  case — viz.,  by  negative  aspiration — the  lungs 
are  kept  distended  within  the  thorax,  hence  the  blood-vessels  of  the 
lungs  containing  air  are  wider  than  those  of  collapsed  lungs  (Quincke 
and  Pfeifler,  Bowditch  and  Garland,  De  Jager).  Hence  also,  more  blood 
flows  through  the  lungs  distended  within  the  thorax  than  through 
collapsed  lungs.  The  dilatation  which  takes  place  during  inspiration 
acts  in  a  similar  manner.  The  negative  pressure  that  obtains  within 
the  lungs  during  inspiration  causes  a  considerable  dilatation  of  the 
pulmonary  veins  into  which  the  blood  of  the  lungs  flows  readily,  whilst 
the  blood  under  high  pressure  in  the  thick-walled  pulmonary  artery 
scarcely  undergoes  any  alteration.  The  velocity  of  the  blood-stream  in 
the  pulmonary  vessels  is  accelerated  during  inspiration  (De  Jager, 
Lalesque). 

The  blood-pressure  in  the  pulmonary  circuit  is  raised  when  the 
lungs  are  inflated.  Contraction  of  small  arteries,  which  causes  an 
increase  of  the  blood-pressure  in  the  systemic  circulation,  also  raises 
the  pressure  in  the  pulmonary  circuit,  because  more  blood  flows  to 
the  right  side  of  the  heart  (v.  Openchowski). 

The  vessels  of  the  pulmonary  circulation  are  very  distensible  and 
their  tonus  is  slight.  [Occlusion  of  one  branch  of  the  pulmonary  artery 
does  not  raise  the  pressure  within  the  aorta  (Beutner).  Even  when 
one  pulmonary  artery  is  plugged  with  an  embolon  of  paraffin,  the 
pressure  within  the  aortic  system  is  not  raised  (Lichtheim).  Thus, 
when  a  large  branch  of  the  pulmonary  artery  becomes  impervious,  the 
obstruction  is  rapidly  compensated,  and  this  is  not  due  to  the  action  of 


BLOOD-PRESSURE   IN  THE   PULMONARY   ARTERY,  179 

the  nervous  system.  The  vaso-motor  system  has  much  less  effect  upon 
the  pulmonary  blood-vessels  than  upon  those  of  the  systemic  circulation 
(Badoud,  Hofmokl,  Liclitheim),  The  compensation  seems  to  be  due 
chiefly  to  the  great  distensibility  and  dilatation  of  the  pulmonary  vessels 
(Lichtheim)]. 

We  know  little  of  the  effect  of  physiological  conditions  upon  the 
pulmonary  artery.  According  to  Lichtheim  suspension  of  the  respiration 
causes  an  increase  of  the  pressure.  [In  one  experiment  he  found  that 
pressure  within  the  pulmonary  artery  was  increased,  Avhile  it  was  not 
increased  in  the  carotid,  and  he  regards  this  experiment  as  proving 
the  existence  of  vaso-motor  nerves  in  the  lung.]  Morel  found  that 
electrical  and  mechanical  stimulation  of  the  abdominal  organs  caused  a 
considerable  rise  of  pressure  in  the  pulmonary  artery  (dog). 

During  the  act  of  great  straining,  the  blood  at  first  flows  rapidly  out  of  the  pul- 
monary veins  and  afterwards  ceases  to  flow,  because  the  inflow  of  blood  into 
the  pulmonary  vessels  is  interfered  with.  As  soon  as  the  straining  ceases,  blood 
flows  rapidly  into  the  pulmonary  vessels  (Lalesque). 

Severini  found  that  the  blood-stream  through  the  lungs  is  greater  and  more  rapid 
when  the  lungs  are  filled  with  air  rich  in  COo  than  when  the  air  wathiu  them 
is  rich  in  O.  He  supposes  that  these  gases  act  upon  the  vascular  ganglia  within 
the  lung,  and  thus  afiect  the  diameter  of  the  vessels. 

Pathoiogical. — increase  of  the  pressure  within  the  area  of  the  pulmonary  artery 
occurs  frequently  in  man,  in  certain  cases  of  heart  disease.  In  these  cases  the 
second  pulmonary  sound  is  always  accentuated,  while  the  elevation  caused  thereby 
in  the  cardiogram  is  always  more  marked  and  occurs  earlier  (§  52). 

[Influence  of  the  Nervous  System.— The  pulmonary  circulation 
is  much  less  dependent  on  the  nervous  system  than  the  systemic 
circulation,  Veiy  considerable  variations  of  the  blood-pressure  within 
the  other  parts  of  the  body  may  occur,  while  the  pressure  within  the 
right  heart  and  puhnonary  artery  is  but  slightly  affected  thereby.  The 
pressure  is  increased  by  electrical  stimulation  of  the  medulla  oblopgata, 
and  it  falls  when  the  medulla  is  destroyed.  Section  and  stimulation 
of  the  central  or  peripheral  ends  of  the  vagi,  stimulation  of  the 
splanchnics,  and  of  the  central  end  of  the  sciatic,  have  but  a  minimal 
influence  on  the  pressure  of  the  pulmonary  artery  (Aubert),] 

89.  Measurement  of  the  Velocity  of  the  Blood-Stream. 

Methods,  (i.)  A.  W.  Volkmann's  HaBmadromometer.— A  glass  tube  of  the 

shape  of  a  hair-pin,  60-130  ctm.  long  and  2  or  3  mm.  broad,  with  a  scale 
etched  on  it,  or  attached  to  it,  is  fixed  to  a  metallic  basal  plate,  B,  so  that  each  limb 
passes  to  a  stop-cock  with  three  channels.  The  basal  plate  is  perforated  along  its 
length,  and  carries  at  each  end  short  cannulse,  c,  c,  which  are  tied  into  the  ends 
of  a  divided  artery.     The  whole  apparatus  is  first  filled  with  water  [or,  better, 


180     MEASUREMENT  OF  THE  VELOCITY   OF    THE  BLOOD-STREAM. 


with   salt   solution].      The  stop-cocks  are  moved  simultaneously,   as  they  are 

attached  to  a  toothed  wheel  and  have  at  first  the  position  given  in  Fig.  81,  I, 

so  that  the  blood  simply  flows  through  the  hole  in  the  y^ 

basal  piece,  i.e.,  directly  from  one  end  of  the  artery  to  j 

the  other.     If  at  a  given  moment  the  stop-cock  is  \ 

turned  in  the  direction  indicated  in  Fig.  81,  II,  the 

blood  has  to  pass  through  the  glass  tube,  and  the  time 

it  takes  to  make  the  circuit  is  noted,  and  as  the  length 

of  the  tube  is  known,  we  can  easily  calculate  the  velocity 

of  the  blood. 

Volkmann  found  the  velocity  to  be  in  the 
carotid  (dog)  =  205  -  357  mm. ;  carotid  (horse)  = 
306;  maxillary  (horse)  =  232;  metatarsal  =56 
mm,  per  second.     The  method  has  very  obvious 


Fig.  81. 

Volkmann's  Hsemadromometer  (B)— I,  blood 

flows  from  artery  to  artery  ;  II,  blood 

must  pass  through   the  glass  tube  of 

B ;  c,c,  cannulse  for  the  divided  artery. 


Y 

Fig.  82. 
Ludwig  &  Dogiel's  Stro- 
muhr  or  Rheometer — 
X,  Y,  axis  of  rotation ; 
A,  B,  glass  bulbs ;  h,  h, 
cannixlse  inserted  in  the 
divided  artery;  e,  ei,  ro- 
tates on  g,  f;  c,  d,  tubes. 


defects  arising  from  the  narrowness  of  the  tube;  the  introduction  of 
such  a  tube  offers  new  resistance,  while  there  are  no  respiratory  or  pulse 
variations  observable  in  the  stream  in  the  glass  tube. 


MEASUREMENT  OF  THE   VELOCITY  OF  THE  BLOOD-STREAM.      181 

(2.)  C.  Lud^vig  and  Dogiel  (1867)  devised  a  stromuhr  or  rheometer, 
for  measuring  the  amount  of  blood  which  passed  through  an  artery  in  a 
given  time  (Fig,  82).  It  consists  of  two  glass  bulbs,  A  and  B,  of  exactly 
the  same  capacity.  These  bulbs  communicate  with  each  other,  above, 
their  lower  ends  being  fixed  by  means  of  the  tubes,  c  and  d,  to  the  metal 
disc,  ecj.  This  disc  rotates  round  the  axis,  X  Y,  so  that,  after  a 
complete  revolution  the  tube,  c,  conmiunicates  with  /,  and  d  with  g ;  f 
and  g  are  provided  with  horizontally  placed  cannulse,  h  and  h,  which  are 
tied  into  the  ends  of  the  divided  artery.  The  cannula,  h,  is  fixed  in 
the  central  end,  and  h  in  the  peripheral  end  of  the  artery  (e.<7.,  carotid); 
the  bulb.  A,  is  filled  with  oil  and  B  with  defibrinated  blood ;  at  a  certain 
moment  the  communication  through  h  is  opened,  the  blood  flows  in, 
driving  the  oil  before  it,  and  passes  into  B,  while  the  defibrinated 
blood  flows  through  k  into  the  peripheral  part  of  the  artery.  As 
soon  as  the  oil  reaches  m — a  moment  which  is  instantly  noted,  or,  what 
is  better,  inscribed  upon  a  revolving  cylinder — the  bulbs,  A,  B,  are 
rotated  upon  the  axis,  X  Y,  so  that  B  comes  to  occupy  the  position 
of  A.  The  same  experiment  is  repeated,  and  can  be  continued 
for  a  long  time.  The  quantity  of  blood  which  passes  in  the  unit 
of  time  (1  sec.)  is  calculated  from  the  time  necessary  to  fill  the  bulb 
with  blood.  Important  results  are  obtained  by  means  of  this 
instrument. 


I 

Fig.  83. 
Vieror  dt's  Hsematachometer — A,  glass ; 
€,  entrance ;  a,  exit  cannula ;  p, 
pendulum. 


(3.)    Vierordt's   Haematachometer 

(1858)  consists  of  a  small  metal  box  (Fig. 
83)  with  parallel  glass  sides.  To  the 
narrow  sides  of  the  box  are  fitted  an 
entrance,  e,  and  an  exit  carmula,  a.  In 
its  interior  is  suspended,  against  the 
entrance  opening,  a  pendulum,  p,  whose 
vibrations  may  be  read  off  on  a  curved 
scale.  [This  instrument,  as  well  as  Volk- 
mann's  apparatus,  has  only  a  historical 
interest.] 


(4.)  Chauveau  and  Lortet's  (Dromograph)  (i860)  is  constructed  on  the  same 
principle.  A  tube,  A,  B  (Fig.  84)  of  sufficient  diameter,  with  a  side-tube  fixed  to 
it,  C,  which  can  be  placed  in  connection  with  a  manometer,  is  introduced  into 
the  carotid  artery  of  a  horse.  At  a  a  small  piece  is  cut  out  and  provided  with  a 
covering  of  gutta-percha  which  has  a  small  hole  in  it ;  through  this  a  light  pen- 
dulum, c,  b,  with  a  long  index,  h,  projects  into  the  tube,  i.e.,  into  the  blood- 
current,  which  causes  the  pendulum  to  vibrate,  and  the  extent  of  the  vibrations  can 
be  read  off  on  a  scale,  S,  S.  G  is  an  arrangement  to  permit  the  instrument  to  be 
held.  Both  this  and  the  former  instrument  are  tested  beforehand  with  a  stream 
of  water  sent  through  them  with  varying  velocities. 

The  curve  of  the  velocity  may  be  written  off  on  a  smoked  glass, 


182 


VELOCITY  OF  THE  BLOOD   IN   THE  BLOOD-VESSELS. 


moving  parallel  with  the  index  h.     The  dromograph  curve,  III,  shows 
the  primary  elevation,  P,  and  the  dicrotic  elevation,  R. 


Dromograph — A,  B,  tube  inserted  in  artery;  C,  lateral  tube  connected  with  a. 
manometer;  6,  index  moving  in  a  caoutchouc  membrane,  a;  G,  handle.  Ill, 
curve  obtained  by  dromograph. 


90.  Velocity  of  the  Blood  in  Arteries,  Capillaries, 
and  Veins. 

(1.)  Division  of  Vessels. — In  estimating  the  velocity  of  the  blood,  it  is 
important  to  remember  that  the  sectional  area  of  all  the  branches  of 
the  aorta  becomes  greater  as  we  proceed  from  the  aorta  towards  the 
capillaries,  so  that  the  capillary  area  is  700  times  greater  than  the 
sectional  area  of  the  aorta  (Vierordt).  As  the  veins  join  and  form 
larger  trunks,  the  venous  area  gradually  becomes  smaller,  but  the 
sectional  area  of  the  venous  orifices  at  the  heart  is  greater  than  that 
of  the  corresponding  arterial  orifices. 

The  common  iliacs  are  an  exception ;  the  sum  of  their  sectional  areas  is  less 
than  that  of  the  aorta ;  the  sections  of  the  four  pulmonary  veins  are  together  less 
than  that  of  the  pulmonary  artery. 

(2.)  Sectional  Area, — An  equal  quantity  of  blood  must  pass  through 
every  section  of  the  circulatory  system,  through  the  pulmonic  as  well 
as  through  the  systemic  circulation,  so  that  the  same  amount  of  blood 
must  pass  through  the  pulmonary  artery  and  aorta,  notwithstanding 
the  very  unequal  blood-pressure  in  these  two  vessels. 


VELOCITY  OF  THE  BLOOD   IN   THE  BLOOD-VESSELS.  183 

(3.)  Lumen. — The  velocity  of  the  current,  therefore,  in  various 
sections  of  the  vessels  must  be  inversely  as  their  lumen. 

(4.)  Capillaries. — Hence,  the  velocity  must  diminish  very  consider- 
ably as  we  pass  from  the  root  of  the  aorta  and  the  pulmonary  artery 
towards  the  capillaries,  so  that  the  velocity  in  the  capillaries  of  mammals 
=  0*8  millimetre  per  sec;  frog=0'53  mm.  (E.H.Weber);  man  =  0-6 
to  0*9  (C,  Vierordt).  According  to  A.  W.  Volkmann  the  blood  in 
mammalian  capillaries  flows  500  times  slower  than  the  blood  in  the 
aorta.  Hence  the  total  sectional  area  of  all  the  capillaries  must  be 
500  times  greater  than  that  of  the  aorta.  Bonders  found  the  velocity 
of  the  stream  in  the  small  afierent  arteries,  to  be  10  times  faster  than 
in  the  capillaries.  A  pulsatory  acceleration,  more  rapid  during  its  first 
phase,  is  observable  in  the  small  arteries,  although  these  are  not 
themselves  distended  thereby. 

Veins. — The  current  becomes  accelerated  in  the  veins,  but  in  the 
larger  trunks  it  is  0*5  to  0*75  times  less  than  in  the  corresponding 
arteries. 

(5.)  Mean  Blood-Pressure. — The  velocity  of  the  blood  does  not 
depend  upon  the  Tnean  blood-pressure,  so  that  it  may  be  the  same  in 
congested  and  in  anaemic  parts  (Volkmann,  Hering). 

(6.)  Difference  of  Pressure. — On  the  other  hand,  the  velocity  in  any 
section  of  a  vessel  is  dependent  on  the  difference  of  the  pressure  vrhich 
exists  at  the  commencement  and  at  the  end  of  that  particular  section 
of  a  blood-vessel ;  it  depends,  therefore,  on  (1)  the  vis  a  tergo  (i.e.,  the 
action  of  the  heart),  and  (2)  on  the  amount  of  the  resistance  at  the 
periphery  (dilatation  or  contraction  of  the  small  vessels — C.  Ludwig 
and  Dogiel). 

(7.)  Pulsatory  Acceleration. — With  every  pulse-beat  a  corresponding 
acceleration  of  the  blood-current  (as  well  as  of  the  blood-pressure)  takes 
place  in  the  arteries,  so  that  every  ascent  of  the  sphygmogram  corre- 
sponds to  an  acceleration,  and  every  descent  to  a  diminished  velocity  of 
the  blood-stream.  The  variations  in  the  velocity  caused  by  the  heart- 
beat are  recorded  in  Fig.  84,  obtained  by  Chauveau's  dromograph  from 
the  carotid  of  a  horse.  The  velocity-curve  corresponds  with  a  sphyg- 
mogram— P  represents  the  primary  elevation  and  E  the  dicrotic  wave. 
This  acceleration,  as  well  as  the  pulse,  disappears  in  the  capillaries. 
In  large  vessels,  Vierordt  found  the  increase  of  the  velocity  during 
the  systole  to  be  greater  by  |-  to  ^  than  the  velocity  during  the 
diastole. 

(8.)  Respiratory  Effect. — Every  inspiration  retards  the  velocity  in  the 
arteries,  every  expiration  aids  it  somewhat;  but  the  value  of  these 
agencies  is  very  small. 

If  we  compare  what  has  already  been  said  regarding  the  effect  of  the  respiration 


184  DURATION   OF  THE  CIRCULATION. 

on  the  contraction  and  dilatation  of  the  heart  and  on  the  blood-stream  (§  60),  it 
is  clear  that  respiration  favours  the  blood-stream,  so  does  artificial  respiration. 
When  artificial  respiration  is  interrupted,  the  blood-stream  becomes  slower  (Dogiel). 
If  the  suspension  of  respiration  lasts  somewhat  longer,  the  current  is  again  acceler- 
ated on  account  of  the  dyspnceic  stimulation  of  the  vaso-motor  centre  (Heidenhain) 
(see  Vaso-motor  centre,  vol.  ii.) 

(9.)  Conditions  Affecting  Velocity  in  the  Veins. — Many  circumstances 
affect  the  velocity  of  the  blood  in  the  veins.  (1)  There  are  regular 
variations  in  the  large  veins  near  the  heart  (Valsalva)  due  to  the 
respiration  and  the  movements  of  the  heart  (§  §  50,  and  60).  (2)  Irregular 
variations  due  to  pressure — e.g.,  from  contracting  muscles  (§  87),  friction 
on  the  skin  in  the  direction  or  against  the  direction  of  the  venous 
current,  the  position  of  a  limb  or  of  the  body.  The  pump-like  action 
of  the  veins  of  the  groin  during  walking  has  been  referred  to  (§  87). 
When  the  lower  limb  is  extended  and  rotated  outwards,  the  femoral 
vein  in  the  iliac  fossa  collapses,  owing  to  an  internal  negative  pressure; 
when  the  thigh  is  flexed  and  raised,  it  fills  under  a  positive  pressure 
(Braune).     A  similar  condition  obtains  in  walking. 


91.  Estimation  of  the  Capacity  of  the  Ventricles. 

Vierordt  calculated  the  capacity  of  the  left  ventricle  from  the  velo- 
city of  the  blood-stream,  and  the  amount  of  blood  discharged  per 
second  by  the  right  carotid,  right  subclavian,  the  two  coronary  arteries, 
and  the  aorta  below  the  origin  of  the  innominate  artery.  He  estimated 
that  with  every  systole  of  the  heart,  172  cubic  centimetres  (equal  to 
182  grammes)  of  blood  were  discharged  into  the  aorta;  this,  therefore, 
must  be  the  capacity  of  the  left  ventricle  (compare  §  83). 


92.  The  Duration  of  the  Circulation. 

The  question  as  to  how  long  the  blood  takes  to  make  a  complete 
circuit  through  the  course  of  the  circulation  was  first  answered  by 
Hering  (1829)  in  the  case  of  the  horse.  He  injected  a  2  per  cent, 
solution  of  potassium  ferrocyanide  into  a  special  vein,  and  ascertained 
(by  means  of  ferric  chloride)  when  this  substance  appeared  in  the 
blood  taken  from  the  corresponding  vein  on  the  opposite  side  of  the 
body.  The  ferrocyanide  may  also  be  injected  into  the  central  or  cardiac 
end  of  the  jugular  vein,  and  the  time  noted  at  which  its  presence  is 
detected  in  the  blood  of  the  peripheral  end  of  the  same  vein]. 
Vierordt  (1858)  improved  this  method  by  placing  under  the  cor- 
responding vein  of  the  opposite  side  a  rotating  disc,  in  which  was 
fixed  a  nun^ber  of  cups  at  regular  intervals.    The  first  appearance  of 


WORK   OF  THE   HEART.  185 

the  potassium  ferrocyanide  is  detected  by  adding  ferric  chloride  to  the 
serum,  which  separates  from  the  samples  of  blood  after  they  have 
stood  for  a  time.     The  duration  of  the  circulation  is  as  follows : — 


Horse,  . 

.     31 'S  seconds. 

Hedgehog,    7  "61  seconds. 

Duck,  . 

.  10  "64  seconds 

Dog,      . 

.     167       „ 

Cat,     .     .     6-69       „ 

Buzzard, 

.     6-73       „ 

Rabbit, 

.      7-79     „ 

Goose,      .10-86 

Fowl,  . 

5-17       ,> 

Results. — When  these  numbers  are  compared  with  the  frequency  of 
the  normal  pulse-beat  in  the  corresponding  animals,  the  following 
deductions  are  obtained  : — 

(1.)  The  mean  time  required  for  the  circulation  is  accomplished 
during  27  heart-beats — i.e.,  for  man  =  23'2  seconds,  supposing  the 
heart  to  beat  72  times  per  minute. 

(2.)  Generally,  the  mean  time  for  the  circulation  in  two  warm-blooded 
animals  is  inversely  as  the  frequency  of  the  pulse-beats. 

Conditions  Influencing  the  Time. — The  time  is  influenced  by  the 
following  factors : — 

1.  Long  vascular  chaimels  (e.g.,  from  the  metatarsal  vein  of  one  foot  to  the 
other  foot)  require  a  longer  time  than  short  channels  (as  between  the  jugulars). 
The  difference  may  be  equal  to  10  per  cent,  of  the  time  required  to  complete  the 
entire  circuit. 

2.  In  young  animals  (with  shorter  vascular  channels  and  higher  pulse-rate)  the 
time  is  shorter  than  in  old  animals. 

3.  Rapid  and  energetic  cardiac  contractions  (as  during  muscular  exercise)  diminish 
the  time.  Hence  rapid  and  at  the  same  time  less  energetic  contractions  (as  after 
section  of  both  vagi),  and  slow  but  vigorous  systoles  {e.g.,  after  slight  stimulation 
of  the  vagus)  have  no  effect. 

C.  Vierordt  estimated  the  quantity  of  blood  in  a  man,  in  the  following 
manner.  In  all  warm-blooded  animals,  27  systoles  correspond  to  the  time  for 
completing  the  circulation.  Hence,  the  total  mass  of  the  blood  must  be  equal  to 
27  times  the  capacity  of  the  ventricle,  i.e.,  in  man,  187 "5  grams,  x  27  =  5062  5 
grams.  This  is  equal  to  ^V  of  the  body-weight,  in  a  person  weighing  65*8  kilos, 
(compare  §  49). 

It  is  not  to  be  forgotten  that  the  salt  used  is  to  some  extent  poisonous  (p.  108). 


93.  Work  of  the  Heart, 

Johann  Alfons  Bernoulli  (1679)  and  Julius  Robert  Mayer  estimated 
the  work  done  by  the  heart.  The  work  of  a  motor  is  expressed  in 
kilogramme-metres — i.e.,  the  number  of  kilos,  which  the  motor  can 
raise  in  the  unit  of  time  to  the  height  of  1  metre. 

The  left  ventricle  expels  0"188  kilo,  of  blood  (Volkmann)  with  each 
systole,  and  in  doing  so  it  overcomes  the  pressure  in  the  aorta,  which 
is  equal  to  a  column  of  blood  3'21  metres  in  height  (Donders).  [The 
amount  of  blood  expelled  from  each  ventricle  during  the  systole  is 
about  180  grms.  (6    ozs.)     It  is  forced   out  against  a  pressure  of 


186  BLOOD-CURRENT  IN   THE  SMALLEST  VESSELS. 

250  mm.  Hg.=  3'21  metres  of  blood.]  The  work  of  the  heart  at  each 
systole  is  0*188  x  3*21  =  0*604  kilogramme-metres.  If  the  number  of 
beats  =75  per  minute,  then  the  work  of  the  left  ventricle  in  24  hours 
=(0*604  X  75  X  60  X  24)  =  65,230  kilogramme-metres.  While  the 
"  work"  done  by  the  right  ventricle  is  about  one-third  that  of  the  left,  and 
therefore =21,740  kilogramme-metres.  Both  ventricles  do  work  equal 
to  86,970  kilogramme-metres.  A  workman  during  eight  hours  produces 
300,000  kilogramme-metres — i.e.,  about  four  times  as  much  as  the  heart. 
As  the  whole  of  the  work  of  the  heart  is  consumed  in  overcoming  the 
resistance  within  the  circulation,  or  rather  is  converted  into  heat,  the 
body  must  be  partly  warmed  thereby  (425*5  gramme-meters  are  equal 
to  1  heat-unit — i.e.,  the  force  required  to  raise  425*5  grammes 
to  the  height  of  1  metre  may  be  made  to  raise  the  temperature  of 
1  cubic  centimetre  of  water  1°C.)  So  that  204,000  "heat-units"  are 
obtained  from  the  transformation  of  the  kinetic  energy  of  the  heart. 

One  gramme  of  coal  when  burned  yields  8,080  heat-units,  so  that 
the  heart  yields  as  much  energy  for  heating  the  body  as  if  about 
25  grammes  of  coal  were  burned  within  it  to  produce  heat. 


94.  Blood-Current  in  the  Smallest  Vessels. 

Methods. — The  most  important  observations  for  this  purpose  are 
made  by  means  of  the  microscope  on  transparent  parts  of  living  animals. 
Malpighi  was  the  first  to  observe  the  circulation  in  this  way  in  the 
lung  of  a  frog  (1661). 

The  following  parts  have  been  employed : — the  tails  of  tadpoles  and  small  fishes ; 
the  web,  tongue,  mesentery,  and  lungs  of  curarised  frogs  (Cowper,  1704) ;  the  wing 
of  the  bat,  the  third  eyelid  of  the  pigeon  or  fowl,  the  mesentery ;  the  vessels  of  the 
liver  of  frogs  and  newts  (Gruithuisen),  of  the  pia  mater  of  rabbits,  of  the  skin  on 
the  belly  of  the  frog,  of  the  mucous  membrane  of  the  inner  surface  of  the  human 
lip  (Hiiter's  Cheiloangioscope,  1879) ;  of  the  conjunctiva  of  the  eyeball  and  eyelids. 
All  these  may  be  examined  by  reflected  light. 

[Eutoptical  appearances  of  the  circulation  (Purkinje,  1825).  Under  certain 
conditions  a  person  may  detect  the  movement  of  the  blood-corpuscles  within  the 
blood-vessels  of  his  own  eye.  The  best  method  is  that  of  Rood,  viz.,  to  look  at  the 
sky  through  a  dark  blue  glass,  or  through  several  pieces  of  cobalt  glass  placed  over 
each  other  (Helmholtz)]. 

Form  and  Arrangement  of  Capillaries.— Regarding  the  form  and  arrange- 
ment of  the  capillaries,  we  find  that — 

1.  The  diameter,  which  in  the  finest,  permits  only  the  passage  of  single  corpuscles 
in  a  row — one  behind  the  other — may  vary  from  5  11-2  n,  so  that  two  or  more 
corpuscles  may  move  abreast  when  the  capillary  is  at  its  widest. 

2.  The  few^iA  is  about  0*5  mm.     They  terminate  in  small  veins. 

3.  The  number  is  very  variable,  and  the  capillaries  are  most  numerous  in  those 
tissues,  where  the  metabolism  is  most  active,  as  in  lungs,  liver,  muscles — ^less 
numerous  in  the  sclerotic  and  in  the  nerve-trunks. 


CAPILLARY   CIRCULATION.  187 

4.  They  form  numerous  anastomoses,  and  give  rise  to  net-works,  whose  form  and 
arrangement  are  largely  determined  by  the  arrangement  of  the  tissue  elements  them- 
selves. They  form  simple  loops  in  the  skin,  and  polygonal  net- works  in  the  serous 
membranes,  and  on  the  surface  of  many  gland  tubes ;  they  occur  in  the  form  of 
elongated  net-works,  with  short  connecting  branches  in  muscle  and  nerve,  as  well 
as  between  the  straight  tubules  of  the  kidney  ;  they  converge  radially  towards  a 
central  point  in  the  lobules  of  the  liver,  and  form  arches  in  the  free  margins  of  the 
iris,  and  on  the  limit  of  the  sclerotic  and  cornea. 

[A  good  contrast  as  to  the  vascularity  of  two  adjacent  parts  is  seen  in  the  gray 
and  white  matter  of  the  brain,  the  former  being  very  vascular,  the  latter  but  slightly 
so,] 

[Direct  termination  of  Arteries  in  Veins. — Arteries  sometimes  terminate 

directly  in  veins,  without  the  intervention  of  capillaries,  e.g.,  in  the  ear  of  the 
rabbit,  in  the  terminal  phalanges  of  the  fingers  and  toes  in  man  and  some  animals, 
in  the  cavernous  tissue  of  the  penis  (Hoyer).  They  may  be  regarded  as  secondary 
channels  which  protect  the  circulation  of  adjacent  parts,  and  they  may  also  be 
related  to  the  heat-regulating  mechanisms  of  peripheral  parts  (Hoyer).] 

End-Arteries. — In  connection  with  the  termination  of  arteries  in  capillaries, 
it  is  important  to  determine  if  the  arterioles  are  "  end  or  terminal  arteries,"  i.e.,  if 
they  do  not  form  any  further  anastomoses  with  other  similar  arterioles,  but 
terminate  directly  in  capillaries,  and  thus  only  communicate  by  capillaries  with 
neighbouring  arterioles — or  the  arteries  may  anastomose  with  other  arteries  just 
before  they  break  up  into  capillaries.  This  distinction  is  important  in  connection 
with  the  nutrition  of  parts  supplied  by  such  arteries  (Cohnheim). 

Capillary  Circulation. — On  observing  the  capillary  circulation,  we 
notice  that  the  red  corpuscles  move  only  in  the  axis  of  the  current 
(axial  current),  while  the  lateral  transparent  plasma- current  flowing  on 
each  side  of  this  central  thread  is  free  from  these  corpuscles.  [The 
axial  current  is  the  more  rapid.]  This  plasma  layer  or  "  Poiseuille's 
space  "  is  seen  in  the  smallest  arteries  and  veins,  where  f  is  taken  up 
with  the  axial  current,  and  the  plasma  layer  occupies  \  on  each  side  of  it 
(Fig.  85).  A  great  many,  but  not  all,  of  the  colourless  corj)uscles  run  in 
this  layer.  It  is  much  less  distinct  in  the  capillaries.  Eud.  Wagner  stated 
that  it  is  absent  in  the  finest  vessels  of  the  lung  and  gills  [although 
Gunning  was  unable  to  confirm  this  statement.]  The  coloured  coi-puscles 
move  in  the  smallest  capillaries  in  single  file  one  after  the  other ;  in, 
the  larger  vessels,  several  corpuscles  may  move  abreast,  with  a  gliding 
motion,  and  in  their  course  they  may  turn  over  and  even  be  tAvisted 
if  any  obstruction  is  off'ered  to  the  blood-stream.  As  a  general  rule,  in 
these  vessels  the  movement  is  uniform,  but  at  a  sharp  bend  of  the 
vessel  it  may  partly  be  retarded  and  partly  accelerated.  Where  a 
vessel  divides,  not  unfrequently  a  corpuscle  remains  upon  the  projecting 
angle  of  the  division,  and  is  doubled  over  it  so  that  its  ends  project 
into  the  two  branches  of  the  tube.  There  it  may  remain  for  a  time, 
until  it  is  dislodged,  when  it  soon  regains  its  original  form  on  account 
of  its  elasticity.  Not  unfrequently  we  see  a  red  corpuscle  becoming 
bent  where  two  vessels  meet,  but  on  all  occasions  it  rapidly  regains 


188  CAPILLARY   CIRCULATION. 

its  original  form.  This  is  a  good  proof  of  the  elasticity  of  the 
coloured  corpuscles. 

Colourless  Corpuscles. — The  motion  of  the  colourless  corpuscles  is 
quite  different  in  character;  they  roll  directly  on  the  vascular  wall, 
moistened  on  their  peripheral  zone  by  the  plasma  in  Poiseuille's  space, 
their  other  surface  being  in  contact  with  the  thread  of  coloured  cor- 
puscles in  the  centre  of  the  stream.  Schklarewsky  has  shown  by 
physical  experiments,  that  the  particles  of  least  specific  gravity  in  all 
capillaries  {e.g.,  of  glass)  are  pressed  toward  the  wall,  while  those  of 
greater  specific  gravity  remain  in  the  middle  of  the  stream.  [Graphite 
and  particles  of  carmine  were  suspended  in  water,  and  caused  to 
circulate  through  capillary  tubes  placed  under  a  microscope,  when  the 
graphite  kept  the  centre  of  the  stream,  and  the  carmine  moved  in  the 
layer  next  the  wall  of  the  tube.] 

When  the  colourless  corpuscles  reach  the  wall  of  the  vessel,  they 
must  roll  along,  partly  on  account  of  their  surface  being  sticky,  whereby 
they  readily  adhere  to  the  vessel,  and  partly  because  one  surface  is 
directed  towards  the  axis  of  the  vessel  where  the  movement  is  most 
rapid,  and  where  they  receive  impulses  directly  from  the  rapidly 
moving  coloured  blood-corpuscles  (Donders).  The  roUing  motion  is 
not  always  uniform,  not  unfrequently  it  is  retrograde  in  direction, 
which  seems  to  be  due  to  an  irregular  adhesion  to  the  vascular 
wall.  Their  slower  movement  (10  to  12  times  slower  than  the 
red  corpuscles)  is  partly  due  to  their  stickiness,  and  partly  to  the 
fact  that  as  they  are  placed  near  the  wall,  a  large  part  of  their 
surface  lies  in  the  peripheral  threads  of  the  fluid,  which  of  course 
move  more  slowly  (in  fact  the  layer  of  fluid  next  the  wall  is  passive — 
p.  117). 

[D.  J.  Hamilton  finds  that,  when  a  frog's  web  is  examined  in  a 
vertical  position,  by  far  the  greater  proportion  of  leucocytes  float  on 
the  upper  surface,  and  only  a  few  on  the  lower  surface,  of  a  small  blood- 
vessel. In  experiments  to  determine  why  the  coloured  corpuscles 
float  or  glide  exclusively  in  the  axial  stream,  while  a  great  many,  but  not 
all,  of  the  leucocytes  roll  in  the  peripheral  layers,  Hamilton  ascertained 
that  the  nearer  the  suspended  body  approaches  to  the  specific  gravity 
of  the  liquid  in  which  it  is  immersed,  the  more  it  tends  to  occupy  the 
centre  of  the  stream.  He  is  of  opinion  that  the  phenomenon  of  the 
separation  of  the  blood-corpuscles  in  the  circulating  fluid  is  due  to  the 
colourless  corpuscles  being  specifically  lighter,  and  the  coloured  either 
of  the  same  or  of  very  slightly  greater  specific  gravity  than  the  blood- 
plasma.  Hamilton  controverts  the  statement  of  Schklarewsky,  and  he 
finds  that  it  is  the  relative  specific  gravity  of  a  body  which  ultimately 
determines  its  position  in  a  tube.     These  experiments  point  to  the 


DIAPEDESIS.  189 


immense  importance  of  a  due  relation  subsisting  between  the  specific 
gravity  of  the  blood-plasma  and  that  of  the  corpuscles.] 


la  the  vessels  iJrsfc  formed  in  the  incubated  egg,  as  well  as  in  those  of  young 
tadpoles,  tlie  movement  of  the  blood  from  the  heart  occurs  in  jerks  (Spallanzani, 
1768),  The  velocity  of  the  blood-stream  is  intluenced  by  the  diameter  of  the 
vessels,  which  undei'go  periodic  changes  of  calibre.  This  change  occurs  not  only 
in  vessels  provided  with  muscular  fibres,  but  also  in  the  capillaries,  which  vary  in 
diameter,  owing  to  the  contraction  of  the  cells  composing  their  walls  (p.  125). 

The  velocity  of  the  blood  is  greater  in  the  pulmonary  than  in  the 
systemic  capillaries  (Hales,  1727);  hence,  Ave  must  conclude  that  the 
total  sectional  area  of  the  pulmonary  capillaries  is  less  than  that  of  all 
the  systemic  capillaries. 


95.  Passage  of  the  Blood-Corpuscles  out  of  the 
Vessels— Diapedesis. 

Diapsdesis. — If  the  circulation  be  studied  in  the  vessels  of  the  mesentery,  we 
may  observe  colourless  corpuscles  passing  out  of  the  vessels  in  greater  or  less  num- 
bers (Fig.  85).  The  mere  contact  with  the  air  suffices  to  excite  slight  inflammation. 
At  first,  the  colourless  corpuscles  in  the  plasma-space  move  more  slowly ;  several 
accumulate  near  each  other,  and  adhere  to  the  walls — soon  they  bore  into  the 
wall,  ultimately  they  pass  quite  through  it,  and  may  wander  for  a  distance  into 
the  peri-vascular  tissues.  It  is  doubtful  whether  they  pass  through  the  so-called 
"  stomato"  which  exist  between  the  endothelial  cells,  or  whether  they  simply  pass 
through  the  cement-substance  between  the  endothelial  cells  (p,  122).  This  process  is 
caMedi  Diapedesis,  and  consists  of  several  acts  : — (a.)  The  adhesion  of  lymph -cells  or 
colourless  corpuscles  to  the  inner  surface  of  the  vessel  (after  moving  more  slowly 
along  the  wall  up  to  this  point).  (6.)  They  send  processes  into  and  through  the 
vascular  wall.  (c. )  The  body  of  the  cell  is  drawn  after  or  follows  the  process, 
whereby  the  corpuscle  appears  constricted  in  the  centre  (Fig.  85,  c).  (d.)  The  com- 
plete passage  of  the  corpuscle  through  the  wall,  and  its  farther  motion  in  virtue  of 
its  own  amceboid  movements.  Hering  observed  that  in  large  vessels  with  peri- 
vascular lymph  spaces,  the  corpuscles  passed  into  these  latter,  hence  cells  are 
found  in  lymph  before  it  has  passed  through  Ijonphatic  glands.  The  caiise  of  the 
diapedesis  is  partly  due  to  the  independent  locomotion  of  the  corpuscles,  and  it  is 
partly  a  physical  act,  viz.,  a  filtration  of  the  colloid  mass  of  the  cell  under  the 
force  of  the  blood-pressure  (Hering) — in  the  latter  respect  depending  upon  the 
intra-vascular  pressure  and  the  velocity  of  the  blood-stream.  Hering  regards  this 
process,  and  even  the  passage  of  the  coloured  corpuscles  through  the  vascular  wall 
as  a  normal  process.  The  red  corpuscles  pass  out  of  the  vessels  when  the  venous 
outflow  is  obstructed,  which  also  causes  the  transudation  of  plasma  through  the 
vascular  wall.  The  plasma  carries  the  coloured  corpuscles  along  with  it,  and  at 
the  moment  of  their  passage  through  the  wall  they  assume  extraordinary  shapes, 
owing  to  the  tension  put  upon  them,  regaining  their  shape  as  soon  as  they 
pass  out  (Cohnheim). 


190 


MOVEMENT  OP  THE  BLOOD   IN   THE  VEINS. 


This  remarkable  phenomenon  was  described  by  Waller  in  1846.     Cohnheim  has 

W  recently  re-described  it,  and  accord- 

ing to  him  the  out-wandering  is  a 
sign  of  inflammation,  and  the 
colourless  corpuscles  which  accum- 
ulate in  the  tissues  are  to  be 
regarded  as  true  pus  corpuscles, 
which  may  undergo  further  in- 
crease by  division. 
Stasis. — When  a  strong  stim  ulus 
acts  on  a  vascular  part,  hyperaemic 
redness  and  swelling  occur.  Micro- 
scopic observation  shows,  that  the 
capillaries  and  the  small  vessels 
are  dilated  and  oi^rfilled  with 
blood-corpuscles;  in  some  cases  a 
temporary  narrowing  precedes  the 
dilatation  ;  simultaneously  the 
velocity  of  the  stream  changes: 
rarely  there  is  a  temporary 
acceleration,  more  frequently  it 
becomes  slower.  If  the  action  of 
the  stim^ulus  or  irritant  be  con- 
tinued, the  retardation  becomes  considerable,  the  stream  moves  in  jerks,  then 
follows  a  to  and  fro  movement  of  the  blood-column — a  sign  that  stagnation  has 
taken  place  in  other  vascular  areas.  At  last,  the  blood-stream  comes  completely 
to  a  standstill — stasis — and  the  blood-vessels  are  plugged  with  blood-corpuscles. 
Numerous  colourless  blood-corpuscles  are  found  in  the  stationary  blood.  Whilst 
these  various  processes  are  taking  place,  the  colourless  corpuscles — more  rarely 
the  red — pass  out  of  the  vessels.  Under  favourable  circumstances  the  stasis  may 
disappear.  The  swelling  which  occurs  in  the  neighbourhood  of  inflamed  parts  is 
chiefly  due  to  the  exudation  of  plasma  into  the  surrounding  tissues.  [The  vapour 
of  chloroform  causes  hypereemia  of  the  web  (Lister).] 


Fig.  85. 
Small  vessel  of  the  mesentery  of  a  frog,  show- 
ing the  diapedesis  of  the  colourless 
corpuscles — w,  w,  vascular  walls  ;  a,  a, 
Poiseuille's  space  ;  r,  r,  red  corpuscles  ; 
I,  I,  colourless  corpuscles  adhering  to 
the  Wall,  and  c,  c,  in  various  stages^  of 
extrusion ;  /,  /,  extruded  corpuscles. 


96.  Movement  of  the  Blood  in  the  Veins. 


As  already  mentioned,  in  the  smallest  veins  coming  from  the 
capillaries,  the  blood-stream  is  more  rapid  than  in  the  capillaries  them- 
selves, but  less  so  than  in  the  corresponding  arteries.  The  stream  is 
uniform,  and  if  no  other  conditions  interfered  with  it,  the  venous- 
stream  towards  the  heart  ought  to  be  uniform,  but  many  circumstances 
aflfect  the  stream  in  different  parts  of  its  course.  Amongst  these  are : — 
(1)  The  relative  laxness,  great  disiensibility,  and  the  ready  compressibility 
of  the  walls,  even  of  the  thickest  veins.  (2)  The  incomplete  filling 
of  the  veins,  which  does  not  amount  to  any  considerable  distension 
of  their  walls.  (3)  The  numerous  and  free  anastomoses  between 
adjoining  veins,  not  only  between  veins  lying  in  the  same  plane,  but 
"also  between  superficial  and  deep  veins.  Hence,  if  the  course  of  the 
blood  be  obstructed  in  one  direction,  it  readily  finds  another  outlet. 


MOVEMENT  OF  THE   BLOOD   IN   THE  VEINS.  191 

(4)  The  presence  of  numerous  valves  which  permit  the  blood-stream  to 
move  only  in  a  centripetal  direction  (Fabricius  ab  Aquapendente). 
They  are  absent  from  the  smallest  veins,  and  are  most  numerous  in 
those  of  middle  size. 

Law  of  the  Position,  of  Valves. — The  venous  valves  always  have  two 
pouches,  and  are  placed  at  definite  intervals,  which  correspond  to  the  1,  2,  3,  or 
n"^  power  of  a  certain  "fundamental  distance,"  which  is  =  7  mm.  for  the  lower 
extremity  and  5*5  mm.  for  the  upper.  Many  of  the  original  valves  disappear.  On 
the  proximal  side  of  every  valve  a  lateral  branch  opens  into  the  vein,  while  on  the 
distal  side  of  each  branch  lies  a  valve.  The  same  is  true  for  the  lymphatics 
(K.  Bardeleben). 

Effect  of  Pressure. — As  soon  as  pressure  is  applied  to  the  veins,  the 
next  lowest  valves  close,  and  those  immediately  above  the  seat  of 
pressure  open  and  allow  the  blood  to  move  freely  toward  the  heart. 
The  pressure  may  be  exerted  from  without,  as  by  anything  placed 
against  the  body;  the  thickened  contracted  muscles,  especially  the  muscles 
of  the  limbs,  compress  the  veins.  That  the  blood  flows  out  of  a 
divided  vein  more  rapidly  when  the  muscles  contract,  is  shown  during 
venesection.  If  the  muscles  are  kept  contracted,  the  venous  blood 
passing  out  of  the  muscles  collects  in  the  passive  parts — e.g.,  in  the 
cutaneous  veins.  The  pulsatile  pressure  of  the  arteries  accompanying 
the  veins  favours  the  venous  current  (Ozanam). 

From  a  hydrostatic  point  of  view,  the  valves  are  of  considerable 
importance,  as  they  serve  to  divide  the  column  of  blood  into  segments 
{e.g.,  in  the  crural  vein  in  the  erect  attitude),  so  that  the  fine  blood- 
vessels in  the  foot  are  not  subjected  to  the  whole  amount  of  the 
hydrostatic  pressure  in  the  veins. 

The  velocity  of  the  venous  blood  has  been  measured  directly  (with  the  hsema- 
dromometer  and  the  stromuhr— §  89).  Volkmann  found  it  to  be  225  mm.  per  sec. 
in  the  jugular  vein.  P^eil  observed  that  2i  times  more  blood  flowed  fi-om  an 
arterial  orifice  than  from  a  venous  orifice  of  the  same  size.  The  velocity  of  the 
venous  current  obviously  depends  upon  the  sectional  area  of  the  vessel.  Borelli 
estimated  the  capacity  of  the  venous  system  to  be  4  tunes  greater  than  that  of  the 
arterial ;  while,  according  to  Haller,  the  ratio  is  9  to  4. 

As  we  proceed  from  the  small  veins  towards  the  venae  cav£e,  the 
sectional  area  of  the  veins,  taken  as  a  whole,  becomes  less,  so  that  the, 
velocity  of  the  current  increases  in  the  same  ratio.  The  velocity  of  the 
current  in  the  vense  cavse  may  be  about  half  of  that  in  the  aorta 
(Haller). 

As  the  pulmonary  veins  are  narrower  than  the  pulmonary  artery, 
the  blood  moves  more  rapidly  in  the  former.     The  velocity  of  the 
blood-current  in  the  veins  is  accelerated  during  inspiration — compare 
§  88  (De  Jager). 
[Active  pulsation  occurs  in  the  veins  of  the  wing  of  the  bat  (Schiff).] 


192  SOUNDS   WITHIN  ARTERIES. 

97.  Sounds  or  Bruits  within  Arteries. 

These  murmurs,  sounds,  or  bruits  occur  either  spontaneously,  or  are  produced 
by  the  application  of  external  pressure,  whereby  the  lumen  of  the  vessel  is 
diminished.  In  four-fifths  of  all  healthy  men  two  sounds— corresponding  in 
duration  and  other  characters  to  the  two  heart-sounds— are  heard  in  the  carotid 
(Conrad,  WeU).  Sometimes  only  the  second  heart-sound  is  distinguishable,  as  its 
place  of  origin  is  near  to  the  carotid.  They  are  not  true  arterial  sounds,  but  are 
simply  *^ propagated  heart-sounds.^'' 

Arterial  Sounds  or  murmurs  are  readily  produced  by  pressing  upon 
a  strong  artery — e.g.,  the  crural  in  the  inguinal  region,  so  as  to  leave 
only  a  narrow  passage  for  the  blood  ("Stenosal  murmur").  A  fine 
blood-stream  passes  with  great  rapidity  and  force  through  this  narrow 
part,  into  a  wider  portion  of  the  artery  lying  behind  the  point  of  com- 
pression. Thus  arises  the  "  pressure-stream "  (P.  Memeyer),  or  the 
"fluid  vein"  ("  Veine  fluide"  of  Chauveau.)  The  particles  of  the  fluid 
are  thrown  into  rapid  oscillation,  and  undergo  vibratory  movements, 
and  by  their  movement  produce  the  sound  within  the  peripheral 
dilated  portion  of  the  tube.  A  sound  is  produced  in  the  fluid  by 
pressure  (Corrigan,  Heynsius).  The  sounds  are  not  caused  by  vibra- 
tions of  the  vascular  wall,  as  supposed  by  Bouillaud. 

A  murmur  of  this  sort  is  the  "sub-clavicular  murmur"  (Roser),  occasionally 
heard  during  systole  in  the  subclavian  artery;  it  occurs  when  the  two  layers  of  the 
pleura  adhere  to  the  apex  of  the  lung  (especially  in  tubercular  diseases  of  the 
lungs),  whereby  the  subclavian  artery  undergoes  a  local  constriction  due  to  its 
being  made  tense  and  slightly  curved  (Friedreich).  This  result  is  indicated  in  a 
diminution  or  absence  of  the  pulse-wave  in  the  radial  artery  (Weil). 

Arterial  murmurs  are  favoured  by — (1)  Sufiicient  delicacy  and 
elasticity  of  the  arterial  walls  (Th.  Weber).  (2)  Diminished  peri- 
pheral resistance — e.g.,  an  easy  outflow  of  the  fluid  at  the  end  of  the 
stream  (Kiwisch).  (3)  Accelerated  current  in  the  vascular  system 
generally.  (4)  A  considerable  difi'erence  of  the  pressure  in  the 
narrow  and  wide  portions  of  the  tube  (Marey).  (5)  Large  calibre  of 
the  arteries. 

It  is  obvious  that  arterial  murmurs  will  occur  in  the  human  body: — {a.)  When, 
owing  to  pathological  conditions,  the  arterial  tube  is  dilated  at  one  part,  into  which 
the  blood-current  is  forcibly  poured  from  the  normal  narrow  tube.  Dilatations  of 
this  sort  are  called  aneurisms,  within  which  murmurs  are  generally  audible. 
(b.)  When  pressure  is  exerted  upon  an  artery— e.g.,  by  the  pressure  of  the  greatly 
enlarged  arteries  during  pregnancy,  or  by  a  large  tumour  pressing  upon  a  large 
artery,  (c.)  A  murmur  corresponding  to  each  pulse-beat  is  heard,  especially  where 
two  or  more  large  arteries  lie  together  j  hence,  during  pregnancy,  we  hear  the  uterine 
murmur,  or  placental  bruit,  or  souffle  in  the  greatly  dilated  uterine  arteries.  It  is 
much  less  distinct  in  the  umbilical  arteries  of  the  cord  (umbilical  murmurs).  Similar 
sounds  are  heard  through  the  thin  walls  of  the  head  of  infants  (Fisher,  1833).  A 
murmur  due  to  the  systole  of  the  heart  is  often  heard  in  the  carotid  (Jurasz).    In  such 


VENOUS   MURirURS.  193 

cases  where  no  source  of  external  pressure  is  discoverable,  and  when  no  aneurism 
is  present,  the  spontaneously  occurring  sounds  are  favoured,  when  at  the  moment 
of  arterial  rest  (cardiac  systole)  the  arterial  walls  are  distended  to  the  slightest 
extent,  and  when  during  the  movement  of  the  pulse  (cardiac  diastole)  the  tension 
is  most  rapid  (Traube,  Weil) — i.e.,  when  the  low  systolic  minimum  tension  of  the 
arterial  wall  passes  rapidly  into  the  high  maximum  tension.  This  is  especially  the 
case  in  insufficiency  of  the  aortic  valves,  in  which  case  the  sounds  in  the  arteries 
are  audible  over  a  wide  area.  If  the  minimum  tension  of  the  arterial  wall  is 
relatively  great,  even  during  diastole,  the  sounds  in  the  arteries  are  greatly 
diminished. 

In  insufficiency  of  the  aortic  valves,  characteristic  soiuids  may  be  heard  in  the 
crural  arterj-.  If  pressure  be  exerted  upon  the  artery,  a  double  blowing  murmur  is 
heard;  the  first  one  is  due  to  a  large  mass  of  blood  being  propelled  into  the  artery 
synchronously  with  the  heart-beat,  the  second  to  the  fact  that  a  large  quantity  of 
blood  flows  back  into  the  heart  during  diastole  (Duroziez,  1861).  If  no  pressure 
be  exercised  two  sounds  are  heard,  and  these  seem  to  be  due  to  a  wave  propagated 
into  the  arteries  by  the  auricles  and  ventricles  respectively  (Landois)— compare 
§  73,  Fig.  62,  III.     In  atheroma  a  double  sound  may  sometimes  be  heard  (§  73,  2). 

98.  Venous  Murmurs. 

I.  Bruit  de  Diable. — This  sound  is  heard  above  the  clavicles  in  the 
furrow  between  the  two  heads  of  the  stemo-mastoid,  most  frequently 
on  the  right  side,  and  in  40  per  cent,  of  all  persons  examined.  It  is 
either  a  continuous  or  a  rhythmical  murmur,  occurring  during  the 
diastole  of  the  heart  or  during  inspiration ;  it  has  a  whistling  or 
rushing  character,  or  even  a  musical  quality,  and  arises  within  the 
bulb  of  the  common  jugular  vein.  When  this  sound  is  heard  without 
pressure  being  exerted  by  the  stethoscope,  it  is  a  pathological  phe- 
nomenon. If,  however,  pressure  be  exerted,  and  if,  at  the  same  time, 
the  person  examined  turns  his  head  to  the  opposite  side  a  similar 
sound  is  heard  in  nearly  all  cases  (Weil).  The  pathological  bruit  de 
cliablc  occurs  especially  in  ansemic  persons,  in  lead-poisoning,  syphilitic 
and  scrofulous  persons,  sometimes  in  young  persons,  and  less  frequently 
in  elderly  people.     Sometimes  a  thrill  of  the  vascular  wall  may  be  felt. 

Causes. — It  is  due  to  the  vibration  of  the  blood  flowing  in  from  the 
relatively  narrow  part  of  the  common  jugular  vein  into  the  wide 
bulbous  portion  of  the  vessel,  and  seems  to  occur  chiefly  when  the 
walls  of  a  thin  part  of  the  vein  lie  close  to  each  other,  so  that  the 
current  must  purl  through  it.  It  is  clear  that  pressure  from  without, 
or  lateral  pressure,  as  by  turning  the  head  to  the  opposite  side,  must 
favour  its  occiurrence.  Its  intensity  will  be  increased  when  the  velocity 
of  the  stream  is  increased,  hence  inspiration  and  the  diastolic  action 
of  the  heart  (both  of  which  assist  the  venous  current)  increase  it.  The 
erect  attitude  acts  in  a  similar  manner.  A  similar  bruit  is  sometimes, 
though  rarely,  heard  in  the  subclavian,  axillary,  thyroid  (scrofula),  facial, 
innominate  and  crural  veins  and  superior  cava. 

13 


194  THE   VENOUS   fULSE. 

II.  Begurgita/Ilt  Murnaiirs. — On  making  a  sudden  effort,  a  murmur  may  be 
heard  in  the  crural  vein  during  expiration,  which  is  caused  by  a  centrifugal  current 
of  blood,  owing  to  the  incompetence  or  absence  of  the  valves  in  this  region.  If  the 
valves  at  the  jugular  bulb  are  not  tight,  there  may  be  a  bruit  with  expiration  (ex- 
piratory  jugular  vein  bruit — Hamernjk),  or  during  the  cardiac  systole  (systolic 
jugular  vein  bruit — v.  Bamberger). 

III.  Valvular  Sounds  in  Veins. — When  the  tricuspid  valve  is  incompetent, 
during  the  ventricular  systole,  a  large  volume  of  blood  is  propelled  backwards  into 
the  venas  cavse.  The  venous  valves  are  closed  suddenly  thereby  and  a  sound  pro- 
duced. This  occurs  at  the  bulb  or  dilatation  on  the  jugular  vein  (v.  Bamberger), 
and  in  the  crural  vein  at  the  groin  (N.  Friedreich),  i.e.,  only  as  long  as  the  valves 
are  competent.  Forced  expiration  may  cause  a  valvular  sound  in  the  crural  vein. 
No  sound  is  heard  in  the  veins  under  perfectly  normal  circumstances. 


99.  The  Venous  Pulse—Phlebogram. 

Methods. — A  tracing  of  the  movements  of  a  vein,  taken  with  a  lightly  weighted 
Sphygmograph,  has  a  characteristic  form  and  is  called  a  phlehogram  (Fig.  86).  In 
order  to  interpret  the  various  events  of  the  phlebogram  it  is  most  important  to 
record  simultaneously  the  events  that  take  place  in  the  heart.  The  auricular  con- 
traction (compare  Fig.  29,  p.  88),  is  synchronous  with  ah;  be,  with  the  ven- 
tricular systole,  during  which  time  the  first  sound  occurs,  whilst  a,  &  is  a 
presystolic  movement.  The  carotid  pulse  coincides  nearly  with  the  apex  of  the 
cardiogram,  i.e.,  almost  simultaneously  with  the  descending  limb  of  the  phlebogram 
(Riegel). 

Occasionally  in  healthy  individuals  a  pulsatile  movement,  synchronous 
with  the  action  of  the  heart,  may  be  observed  in  the  common  jugular 
vein.  It  is  either  confined  to  the  lower  part  of  the  vein,  the  so- 
called  bulb,  or  extends  farther  up  along  the  trunk  of  the  vein.  In 
the  latter  case,  the  valves  above  the  bulb  are  insufiicient,  which  is  by  no 
means  rare,  even  in  health.  The  wave-motion  passes  from  below  up- 
wards, and  is  most  obvious  when  the  person  is  in  the  passive  horizontal 
position,  and  it  is  more  frequent  on  the  right  side,  because  the  right 
vein  lies  nearer  the  heart  than  the  left. 

The  venous  pulse  resembles  very  closely  the  tracing  of  the  cardiac 
impulse  (Landois).     Compare  Fig.  86,  1,  with  Fig.  25a,  A,  p.  82. 

It  is  obvious  that,  as  the  jugular  vein  is  in  direct  communication 
with  the  right  auricle,  and  as  the  pressure  within  it  is  low,  the  systole  of 
the  right  auricle  must  cause  a  positive  wave  to  be  propagated  towards 
the  peripheral  end  of  the  jugular  vein.  Fig.  86,  9  and  10,  are  venous 
pulses  of  a  healthy  person  with  insufiiciency  of  the  valves  of  the  jugular 
vein.  In  these  curves,  the  part  a,  b,  corresponds  to  the  contraction  of 
the  auricle.  Occasionally  this  part  consists  of  two  elevations,  corre- 
sponding to  the  contraction  of  the  atrium  and  auricle  respectively.  As 
the  blood  in  the  right  auricle  receives  an  impulse  from  the  sudden 
tension  of  the  tricuspid  valve,  isochronous  with  the  systole  of  the  right 
ventricle,  there  is  a  positive  wave  in  the  jugular  vein  in  Fig.  86,  9  and 


THE   VENOUS   I'ULSE. 


195 


10..  indicated  by  h,  c.  Lastly,  the  sudden  closure  of  the  pulmonary 
valves  may  even  be  indicated  (c).  As  the  aorta  lies  in  direct  relation 
with  the  pulmonary  artery,  the  sudden  closure  of  its  valves  may  also  be 
indicated  (Fig.  86,  9,  at  d).  During  the  diastole  of  the  auricle  and 
ventricle,  blood  flows  into  the  heart,  so  that  the  vein  partly  collapses 
and  the  lever  of  the  recording  instrument  descends  (Riegel,  Fran9ois- 
Franck). 

The  blood  in  tlie  sinuses  of  the  hrain  also  undergoes  a  pulsatile  movement,  owing 
to  the  fact  that  during  cardiac  diastole  much  blood  flows  into  the  veins  (Mosso). 
Under  favourable  circumstances,  this  movement  may  be  propagated  into  the  veins 
of  the  retina,  constituting  the  wwows  retinal  pulse  of  the  older  observers  (Helfrich). 

Jugular  Vein  Pulse. — The  venous  pulse  in  the  jugular  vein  is  far  better 
marked  in  insufflciency  of  the  tricuspid  valve,  and  the  vein  may  pulsate  violently, 
but  if  its  valves  be  perfect  the  pulse  is  not  propagated  along  the  vein,  so  that  a 
pulse  in  the  jugular  vein  is  not  necessarily  a  sign  of  insufficiency  of  the  tricuspid  valve, 
but  only  of  insufficiency  of  the  valve  of  the  jugular  vein  (Friedreich). 

Liver    Pulse. — The    ventricular  systole  is   propagated    into     the    valve-less 


Various  fox-ms  of  venous  pulses,  chiefly  after  Friedreich — 1-8  from  insufficiency  of 
the  tricuspid  ;  9  and  10,  pulse  of  the  jugular  vein  of  a  healthy  person.  In  all 
the  curves,  a,  6= contraction  of  the  right  auricle;  6,  c,  of  the  right  ventricle  ; 
d,  closure  of  the  aortic  valves ;  e,  closure  of  the  pulmonary  valves  ;  e,  f, 
diastole  of  the  right  ventricle. 

inferior  vena  cava,  and  causes  the  liver  pulse.     With  each  systole  blood  passes  into 
the  hepatic  veins,  so  that  the  liver  undergoes  a  systolic  stoelling  and  injection. 


196  DISTRIBUTION   OF  THE   BLOOD. 

Fig.  86,  2-8,  are  curves  of  the  pulse  in  the  common  jugular  vein  (after  Friedreich). 
Although  at  first  sight  the  curves  appear  to  be  very  different,  they  all  agree  in  this, 
that  the  various  events  occurring  in  the  heart  during  a  cardiac  revolution  are 
indicated  more  or  less  completely.  In  all  the  curves,  a,  6  =  auricular  contraction. 
The  auricle,  when  it  contracts,  excites  a  positive  wave  in  the  veins  (Gendrin,  1843, 
Marey,  Friedreich).  The  elevation,  6,  c,  is  caused  by  the  large  blood- wave 
produced  in  the  veins,  owing  to  the  emptying  of  the  ventricle.  It  is  always  greater, 
of  course,  in  insufficiency  of  the  tricuspid  valves  than  under  normal  circumstances 
(Fig.  86, 9  and  10).  In  the  latter  case,  the  closure  of  the  tricuspid  valve  causes  only 
a  slight  wave-motion  in  the  auricle.  The  apex,  c,  of  this  wave  may  be  higher  or 
lower,  according  to  the  tension  in  the  vein  and  the  pressure  exerted  by  the  sphygmo- 
graph.  As  a  general  rule,  at  least  one  notch  (4,  5,  6,  e)  follows  the  apex,  due  to 
the  prompt  closure  of  the  valves  of  the  pulmonary  artery.  The  closure  of  the 
closely  adjacent  aortic  valves  may  cause  a  small  secondary  wave  near  to  e  (as  in  1 
and  2,  d).     The  curve  falls  towards/,  corresponding  to  the  diastole  of  the  heart. 

A  well-marked  venous  j)ulse  occurs  when  the  right  auricle  is  greatly 
congested,  as  in  cases  of  insufficiency  of  the  mitral  valve  or  stenosis  of 
the  same  orifice.  In  rare  cases,  in  addition  to  the  pulse  in  the  common 
jugular  vein,  the  external  jugular,  the  facial,  thyroid,  external  thoracic 
veins,  or  even  the  veins  of  the  upper  and  lower  extremities  may 
pulsate. 

A  similar  pulsation  must  occur  in  the  pulmonary  veins  in  mitral 
insufficiency,  but  of  course  the  result  is  not  visible. 

On  rare  occasions,  a  pulse  occurs  in  the  veins  on  the  back  of  the 

hand  and  foot,  owing  to  the  arterial  pulse  being  propagated  through  the 

capillaries  into  the  veins.     This  may  occur  under  normal  circumstances, 

when  the  peripheral  ends  of  the  arteries  become  dilated  and  relaxed 

(Quincke),  or  when  the  blood-pressure  within  these  vessels  rises  rapidly 

and  falls  as  suddenly,  as  in  insufficiency  of  the  aortic  valves. 

In  progressive  effusion  into  the  ^pericardium,  at  first  the  carotid  pulse  becomes 
smaller  and  the  venous  pulse  larger;  beyond  a  certain  pressure,  the  latter  ceases 
(Riegel). 

100.    Distribution  of  the  Blood. 

Methods. — The  methods  adopted  do  not  give  exact  results.  J.  Ranke  ligatured 
the  parts  during  life,  removed  them,  and  investigated  the  amount  of  blood  while 
the  tissues  were  still  warm. 

In  a  rabbit,  one-fourth  of  the  total  amount  of  the  blood  is  found  in 
each  of  the  following  : — a,  in  the  passive  muscles ;  b,  in  the  liver ;  c,  in 
the  organs  of  the  circulation  (heart  and  great  vessels) ;  d,  in  all  other 
parts  together  (.J.  Eanke). 

The  amount  of  blood  is  injluenced  by — (1)  The  anatomical  distribution  (vascularity 
or  the  reverse)  of  the  vessels  as  a  whole ;  (2)  the  diameter  of  the  vessels,  which 
depends  upon  physiological  causes — (a)  on  the  blood-pressure  within  the  vessels ; 
(6)  on  the  condition  of  the  vaso-motor  or  vaso-dilatator  nerves  ;  (c)  on  the  condition 
of  the  tissues  themselves,  e.g.,  the  vessels  of  the  intestine  during  absorption ;  by  the 
vessels  of  muscle  during  muscular  contraction ;  of  vessels  in  inflamed  parts. 


PLETHYSMOGRAPHY,:  197 

Activity  of  an  Organ. — The  most  important  factor,  however,  is  the 
state  of  activity  of  the,  organ  itself;  hence,  the  saying,  "ubi  irritatio,  ibi 
affluxus."  We  may  instance  the  congestion  of  the  salivary  glands 
and  the  gastric  mucous  membrane  during  digestion,  and  the  increased 
vascularity  of  muscles  during  contraction.  As  the  activity  of  organs 
varies  at  different  times,  the  amount  of  Mood  in  the  part  or  organ  goes 
hand-in-hand  toith  the  variations  in  its  states  of  activity  (J.  Ranke). 
When  some  organs  are  congested  others  are  at  rest ;  during  digestion , 
there  is  muscular  relaxation  and  less  mental  activity :  violent  muscular 
exertion  retards  digestion — during  great  congestion  of  the  cutaneous 
vessels  the  activity  of  the  kidneys  diminishes.  Many  organs  (heart, 
muscles  of  respiration,  certain  nerve-centres)  seem  always  to  be  in  a 
uniform  state  of  activity  and  vascularity. 

During  the  activity  of  an  organ,  the  amount  of  lilood  in  it  may  be 
increased  30  per  cent.,  nay  even  47  per  cent.  The  motor  organs  of 
young  muscular  persons  are  relatively  more  vascular  than  those  of  old 
and  feeble  persons  (J.  Ranke). 

During  a  condition  of  mental  activity,  the  carotid  is  dilated,  the  dicrotic  wave 
in  the  carotid  curve  is  increased  (the  radial  shows  the  opposite  condition),  and  the 
pulse  is  increased  in  frequency  (Gley). 

In  the  condition  of  increased  activity,  a  more  rapid  renctval  of  the 
blood  seems  to  occur;  after  muscular  exertion  the  duration  of  the  cir- 
culation diminishes  (Vierordt). 

Age. — The  development  of  the  heart  and  large  vessels  determines  a  different  dis- 
tribution of  the  blood  in  the  child  from  that  which  obtains  in  the  adult.  The  heart  is 
relatively  small  from  infancy  up  to  puberty,  the  vessels  are  relatively  large ;  while 
after  puberty  the  heart  is  large,  and  the  vessels  are  relatively  smaller.  Hence,  it 
follows  that  the  blood-pressure  in  the  arteries  of  the  systemic  circulation  must  be 
lower  in  the  child  than  in  the  adult.  The  pulmonary  artery  is  relatively  wide  in 
the  child,  while  the  aorta  is  relatively  small ;  after  puberty  both  vessels  have 
nearly  the  same  size.  Hence,  it  follows  that  the  blood-pressure  in  the  pulmonary 
vessels  of  the  child  is  relatively  higher  than  that  in  the  adult  (Beneke). 


101.  Plethysmography. 

Plethysmograph. — In  order  to  estimate  and  register  the  amount  of 
blood  in  a  limb  Mosso  devised  an  instrument  (Fig.  87),  which  he 
termed  a  Plethysmograph.  It  is  constructed  on  the  same  principle  as 
the  less  perfect  apparatus  of  Chelius  and  Tick. 

It  consists  of  a  long  cylindrical  glass-vessel,  G,  suited  to  accommodate  a  limb. 
The  opening  through  which  the  limb  is  introduced  is  closed  with  caoutchouc,  and 
the  vessel  is  filled  with  water.  There  is  an  opening  in  the  side  of  the  vessel  in 
which  a  manometer  tube,  filled  to  a  certain  height  with  water,  is  fixed.  As  the 
arm  is  enlarged  with  the  increased  supply  of  arterial  blood  passing  into  it  at  each 


198 


PLETHYSMOGRAPHY. 


pulse-beat,  of  course  the  water  column  in  the  manometer  is  raised.  Fick  placed  a 
float  upon  the  surface  of  the  water,  and  thus  enabled  the  variations  in  the  volume 
of  the  fluid  to  be  inscribed  on  a  revolving  cylinder.     The  curve  obtained  resem- 


Fig.  87. 

Mosso's  Plethysmograph — G,  glass- vessel  for  holding  a  limb;  F,  flask  for  varying 
the  water-pressure  in  G;  T,  recording  apparatus. 

bled  the  pulse-curve;  it  was  even  dicrotic.  In  Fig.  87  the  movement  of  the 
fluid  is  represented  ae  conveyed  to  a  Marey's  tambour,  T,  similar  to  the  recordiug 
apparatus  employed  in  Brondgeest's  Pansphygmograph  (p.  87). 

From  the  curve  obtained  we  learn  that — (1.)  The  pulsatile  variations 
in  the  volume  are  similar  to  the  pulse-curve.  As  the  venous  current  is 
regarded  as  uniform  in  the  passive  limb,  every  increase  of  the  volume- 
curve  indicates  a  greater  velocity  of  the  arterial  current  towards  the 
periphery,  and  vice  versd  (Fick).  (2.)  The  respiratory  undulations 
correspond  to  similar  variations  in  the  blood-pressure  tracing 
(§  85,/).  Vigorous  respiration  and  cessation  of  the  respiration  cause 
a  diminution  of  the  volume.  The  limb  swells  during  straining  (v. 
Basch)  and  coughing,  and  diminishes  during  sighing.  (3.)  Certain 
periodic  undulations  occur,  due  to  the  regular  periodic  contractions 
of  the  small  arteries.  (4.)  Other  undulations,  due  to  various  acci- 
dental causes,  affect  the  blood-pressure :  changes  of  the  position 
of  a  limb  acting  hydrostatically,  and  dilatation  or  contraction  of 
the  vessels  in  other  vascular  regions.  (5.)  Movement  of  the  muscles 
of  the  limb  under  observation  causes  diminution  of  volume  (ex- 
periment of  Fr.  Glisson,  1677);  as  the  venous  current  is  accelerated, 
the  musculature  is  also  very  slightly  diminished  in  volume,  even  when 
the  intra-muscular  vessels  are  dilated.  (6.)  Mental  exercise  causes  a 
diminution  in  the  volume  of  the  limb,  and  so  does  sleep  (Mosso). 
Music  influences  the  blood-pressure  in  dogs,  the  pressure  rising  or  falling 
under  different  conditions.  The  stimulation  of  the  auditory  nerve 
is  transmitted  to  the  medulla  oblongata,  where  it  acts  so  as  to  cause 
acceleration  of  the  action  of  the  heart  (Dogiel).  Compression  of  the 
afferent  artery  causes  a  decrease,  and  compression  of  the  vein  an 
iflcre^se  in  thq  volipne  gf  the  limb  (Mosso). 


TRANSFUSION   OF   BLOOD.  199 


102.  Transfusion  of  Blood. 

Transfusion  is  the  introduction  of  blood  from  one  animal  into  the 
vascular  system  of  another  animal. 

Historical. — The  first  indication  of  direct  transfusion  from  blood-vessel  to 
blood-vessel  dates  from  the  time  of  Cardanus  in  1556.  After  the  discovery  of  the 
circulation  in  England,  J.  Potter  (1638)  evolved  the  idea  of  transfusion  of  blood. 
Numerous  experiments  were  made  on  animals.  New  blood  was  transfused  in 
order  to  restore  life  in  animals  that  had  been  bled.  Boyle  and  Lower  conducted 
these  and  other  experiments.  The  blood  of  the  same  species,  as  well  as  the  blood 
of  other  species,  was  employed.  The  first  case  of  transfusion  on  man  was  per- 
formed by  Jean  Denis  in  Paris  (1667),  lamb's  blood  being  used.  At  the  present 
time,  when  transfusion  is  practised  on  man,  only  human  blood  is  used. 

{a)  The  red  corpuscles  are  the  most  important  elements  in 
connection  with  the  restorative  powers  of  the  blood.  They  seem  to 
preserve  their  functions  even  in  blood  which  has  been  defibrinated 
outside  the  body  (Prevost  and  Dumas,  1821).  The  effect  of  various 
reagents  upon  them  has  already  been  noticed  (§  4,  A). 

(6.)  With  regard  to  the  gases  of  the  blood-corpuscles,  oxygenated 
(arterial)  blood  never  acts  injuriously;  but  venous  blood  overcharged 
with  carbonic  acid  ought  only  to  be  transfused  when  the  respiration  is 
sufficient  to  oxygenate  the  blood  as  it  passes  through  the  pulmonary 
capillaries,  whereby  venous  is  transformed  into  arterial  blood.  If  the 
respiratory  movements  have  ceased,  or  are  imperfectly  performed,  the 
blood  becomes  rapidly  richer  in  carbonic  acid  and  in  this  condition 
reaches  the  heart ;  thence  it  is  propelled  into  the  blood-vessels  of  the 
medulla  oblongata,  where  it  acts  as  a  powerful  stimulus  of  the  respira- 
tory centre,  causing  dyspnoea,  convulsions,  and  death. 

(c.)  The  FIBRIN,  or  the  substances' from  which  it  is  formed  (§  29), 
do  not  seem  to  play  any  part  in  connection  with  the  restorative 
powers  of  the  blood ;  hence,  defibrinated  blood  performs  all  the  func- 
tions of  non-defibrinated  blood  within  the  body  (Panum,  Landois), 

(f?.)  The  investigations  of  Worm  Midler  showed  that  an  excess  of 
83  per  cent,  of  blood  might  be  transfused  into  the  vascular  system 
of  an  animal  without  producing  any  injurious  effects.  Hence  it  follows 
that  the  vascular  system  has  the  power  of  accommodating  large  quan- 
tities of  blood  within  it.  That  the  vascular  system  can  accommodate 
itself  to  a  diminished  amount  of  blood  has  been  known  for  a  long 
time. 

When  Employed. — The  transfusion  of  blood  is  used — (1.)  in  Muta 
ancemia  (§  41,  I),  e.g.,  after  copious  hsemorrhage.  New  blood  from  the 
same  species  of  animal  is  introduced  directly  into  the  vessels,  to  supply 
the  place  of  the  blood  lost  by  the  hasmorrhage. 


200  TRANSFUSION    OF  BLOOD. 

(2.)  In  cases  of  'poisoning,  where  the  blood  has  been  rendered  use- 
less by  being  mixed  with  a  poisonous  substance,  and  hence  is  unable 
to  support  life.  In  such  cases,  remove  a  considerable  quantity  of  the 
blood,  and  replace  it  by  fresh  blood.  Carbonic  oxide  is  a  poison  of 
this  kind  (Kiihne),  and  its  eflfects  on  the  body  have  already  been 
described  (compare  p.  32).  The  indication  is  also  obtained  for  a 
similar  practice  in  poisoning  with  ether,  chloral,  chloroform,  opium, 
morphia,  strychnine,  cobra  poison. 

(3.)  Under  certain  patJiological  conditions,  the  blood  may  become  so 
altered  in  quaUty  as  to  be  unable  to  support  life.  The  morphological 
elements  of  the  blood  may  be  altered,  and  so  may  the  relative  propor- 
tion of  its  other  constituents.  Amongst  these  conditions,  may  be  cited 
the  pathological  condition  of  uraemia,  due,  it  may  be,  to  the  accumula- 
tion of  urea  or  the  products  of  its  decomposition  within  the  blood  [or 
to  the  retention  of  the  potash  and  other  urinary  salts — Feltz  and 
Ritter] ;  accumulation  of  the  biliary  constituents  in  the  blood  (Cholsemia), 
and  great  increase  of  the  carbonic  acid.  AU  these  three  conditions,  when 
very  pronounced,  may  cause  death.  In  these  cases  part  of  the  impure 
blood  may  be  replaced  by  normal  human  blood  (Landois). 

Amongst  conditions  where  the  morphological  constituents  of  the  blood 
are  altered  qualitatively  or  quantitatively  are :  hydrsemia  (excessive 
amount  of  water  in  the  blood  §  41,  1) ;  oligocythaemia  (abnormal  dimi- 
nution of  red  blood-corpuscles).  When  these  conditions  are  highly 
developed,  more  especially  in  pernicious  anaemia  (§  10,  2),  healthy 
blood  may  be  substituted.  Transfusion  is  not  suited  for  persons  suffer- 
ing from  leukaemia  (compare  p.  23). 

After-Effects. — A  quarter  or  half  an  hour  after  normal  blood  has  been 
injected  into  the  blood-vessels  of  a  man,  there  is  a  greater  or  less  febrile 
reaction,  according  to  the  amount  of  blood  transfused  (compare  Fever). 

Operation. — The  opei'ative  procedure  to  be  adopted  in  the  process  of  trans- 
fusion varies  according  as  defibrinated  or  non-defibrinated  blood  is  used.  In  order 
to  defibrinate  blood,  some  blood  is  withdrawn  from  a  vein  of  a  healthy  man  in  the 
ordinary  way,  it  is  collected  in  an  open  vessel  and  whipped  or  beaten  with  a  glass 
rod  until  all  the  fibrin  is  completely  removed  from  it.  It  is  then  filtered  through 
an  atlas  filter,  heated  to  the  temperature  of  the  body  (by  placing  it  in  warm  water) 
and  injected  by  means  of  a  syringe  into  an  artery  opened  for  the  purpose.  A  vein 
{e.g.,  basilic  or  great  saphenous)  may  be  selected  for  the  transfusion,  in  which  case 
the  blood  is  driven  in,  in  the  direction  of  the  heart;  if  an  artery  is  selected  (radial 
or  posterior  tibial)  the  blood  is  injected  towards  the  periphery  (Hviter),  or  towards 
the  heart  (Landois,  Unger,  Schafer). 

Dangers. — it  is  most  important  not  to  permit  the  entrance  of  air  into  the  circu- 
lation, for  if  it  be  introduced  in  sufficient  quantity,  it  may  cause  death.  When  air 
enters  the  circulation  it  reaches  the  right  side  of  the  heart  where,  owing  to  the 
movement  of  the  blood,  it  forms  air-bubbles  and  makes  a  froth.  The  air-bubbled 
are  pumped  into  the  branches  of  the  pulmonary  artery,  in  which  they  become 
impacted,  arrest  the  pulmonary  circulation,  and  rapidly  cause  death. 


TRANSFUSION   OF  BLOOD.  201 

If  non-defibrinated  human  blood  is  used,  the  blood  may  be  passed  directly  from 
the  arm  of  the  giver  to  the  arm  of  the  receiver  by  means  of  a  flexible  tube.  The 
tube  used  must  be  filled  with  normal  saline  solution  to  prevent  the  entrance  of  air. 

Peritoneal  Transfusion. — Kecently,  the  injection  of  defibrinated  blood  into 
the  peritoneal  cavity  has  been  recommended.  The  blood  so  injected  is  absorbed 
(Ponfick).  Even  after  twenty  minutes  the  number  of  blood-corpuscles  in  the 
blood  of  the  recipient  (rabbit)  is  increased,  and  the  number  is  gi-eatest  on  the  first 
or  second  day  (Bizzozero  and  Golgi).  The  operation,  however,  may  cause  death, 
and  one  fatal  case,  owing  to  peritonitis,  is  recorded  (Hosier).  It  is  evident  that 
this  method  of  transfusion  is  not  applicable  in  cases  where  blood  must  be  intrg- 
duced  into  the  circulation  as  rapidly  as  possible  (e.f/.,  after  severe  haemorrhage  or 
in  certain  cases  of  poisoning).  [Blood  has  been  injected  into  the  subcutaneous 
cellular  tissue  of  the  abdomen  in  cases  of  great  debility.] 

Heterogeneous  Blood. — The  blood  of  animals  ought  never  to  be  trans  f2ised  into 
the  blood-vessels  of  man.  Some  surgeons  have  transfused  blood  directly  from  the 
carotid  of  a  lamb  into  the  human  subject.  It  is  to  be  remembered,  however,  that 
the  blood- corpuscles  of  the  sheep  are  rapidly  dissolved  by  human  blood,  so  that 
the  active  constituents  of  the  blood  are  rendered  useless  (Landois).  As  a  general 
rule,  the  blood-serum  of  many  mammals  dissolves  the  blood-corpuscles  of  other 
mammals  (§  5,  5). 

Solution  of  the  Blood-Corpuscles. — The  serum  of  dogs  Ijlood  is  a  powerful 
solvent,  while  that  of  the  blood  of  the  horse  and  rabbit  dissolves  corpuscles  rela- 
tively slowly.  The  blood-corpuscles  of  mammals  vary  very  greatly  with  reference 
to  their  power  to  resist  the  solvent  action  of  the  serum  of  other  animals.  The  red 
blood-corpuscles  of  rabbit's  blood  are  rapidly  dissolved  by  the  blood-serum  of 
other  animals,  whilst  those  of  the  cat  and  dog  resist  the  solvent  action  much 
longer.  Solution  of  the  corpuscles  occurs  in  defibrinated  as  well  as  in  ordinary 
blood.  When  the  blood  of  a  rabbit  or  lamb  is  injected  into  the  blood-vessels  of  a 
dog  they  are  dissolved  in  a  few  minutes.  If  blood  be  withdrawn  by  pricking  the 
skin  with  a  needle,  the  partially  dissolved  corpuscles  may  be  detected. 

Liberation  of  Haemoglobin  and  Haemoglobinuria.— As  a  consequence  of 

the  solution  of  the  coloured  corpuscles,  the  blood-plasma  is  reddened  by  the 
liberated  hemoglobin.  Part  of  the  dissolved  material  may  be  used  up  in  the  body 
of  the  recipient,  some  of  it  for  the  formation  of  bile,  but  if  the  solution  of  the 
corpuscles  has  been  extensive,  the  haemoglobin  is  excreted  in  the  urine  (haBmo- 
globinuria)  in  less  amount  in  the  intestine,  the  bronchi,  and  serous  cavities 
(Panum).  Bloody  urine  has  been  observed  in  man  after  the  injection  of  100 
grammes  of  lamb's  blood.  Even  some  of  the  recipient's  own  corpuscles  may  be 
dissolved,  as  in  the  case  where  the  recipient's  blood-corpuscles  are  dissolved  by 
the  serum  of  the  transfused  blood — e.g.,  transfusing  dog's  blood  into  man.  In  the 
rabbit,  whose  corpuscles  are  readily  dissolved,  the  transfusion  of  the  blood-serum 
of  the  dog,  man,  pig,  sheep,  or  cat  produces  serious  symptoms,  and  even  death. 
The  dog,  whose  corpuscles  are  more  resistant,  bears  transfusion  of  other  kinds  of 
blood  well. 

Dangers. — When  foreign  or  heterogeneous  blood  {i.e.,  blood  from  a  different 
species)  is  transfused,  two  phenomena,  which  may  be  dangerous  to  life,  occur : — 

(1.)  Before  the  corpuscles  are  dissolved  they  usually  run  together  and  form 
sticky  masses  consisting  of  10  or  12  corpuscles,  which  are  apt  to  occlude  capillaries. 
After  a  time  they  give  up  their  hsemoglobin,  leaving  the  stroma,  which  yields  a 
sticky  fibrin-like  mass  that  may  occlude  fine  vessels  (p.  48). 

(2.)  The  presence  of  a  large  quantity  of  dissolved  hsemoglobin  may  cause 
extensive  coagitlation  within  the  blood-vessels.  The  injection  of  dissolved  haemo- 
globin causes  extensive  coagulations  (Naunyn  and  Francken). 

The  coagulation  occurs  usually  in  the  venous  system  and  in  the  large  vessels, 
and  may  cause  death  either  suddenly  or  after  a  considerable  time. 


202  TRANSFUSION    OF   OTHER   FLUIDS. 

Dissolved  hJBmoglobin  seems  greatly  to  increase  the  activity  of  the  fibrin-ferment 
(§  30),  perhaps  by  accelerating  the  decomposition  of  the  colourless  corpuscles. 
Hasmoglobin  exposed  to  the  air  gradually  loses  this  property;  and  the  fibrin- 
ferment,  when  in  contact  with  haemoglobin,  is  either  destroyed  or  rendered  less 
active  (Sachssendahl), 

Vascular  Symptoms.— As  a  result  of  the  above-named  causes  of  occlusion  of 
the  vessels,  there  are  often  signs  of  the  circulation  being  impeded  in  various  organs. 
In  man,  after  transfusion  of  lamb's  blood,  the  skin  is  bluish-red,  in  consequence  of 
the  stagnation  of  blood  in  the  cutaneous  vessels.  Difficulty  of  breathing  occurs 
from  obstruction  in  the  capillaries  of  the  lung ;  while  there  may  be  rupture  of  small 
bronchial  vessels,  causing  sanguineous  expectoration.  The  dyspnoea  may  increase, 
especially  when  the  circulation  through  the  medulla  oblongata— the  seat  of  the 
respiratory  centre — is  interfered  with.  In  the  digestive  tract,  for  the  same  reason, 
increased  peristalsis,  evacuation  of  the  contents  of  the  rectum,  vomiting,  and 
abdominal  pain  may  occur.  These  phenomena  are  explained  by  the  fact  that 
disturbances  of  the  circulation  in  the  intestinal  vessels  cause  increased  peristaltic 
movements.  Degeneration  of  the  parenchyma  of  the  kidney  occurs  as  a  result  of 
the  occlusion  of  some  of  the  renal  vessels.  The  uriniferous  tubules  become 
plugged  with  cylinders  of  coagulated  albumin  (Ponfick).  Owing  to  the  occlu?iou 
of  numerous  small  muscular  branches  the  muscles  may  become  stiff',  or  coagulation 
of  their  myosin  may  occur.  Other  symptoms,  referable  to  the  nervous  system,  the 
sense-organs  and  heart,  are  all  due  to  the  interference  with  the  circulation 
through  them.  An  important  sj-mptom  is  the  occurrence  of  a  considerable 
amount  of  fever  half  an  hour  or  so  after  the  transfusion  of  heterogeneous  blood. 
When  many  vessels  are  occluded,  rupture  of  some  small  blood-vessels  may  take 
place.  This  explains,  the  occurrence  of  slight  yet  persistent  haemorrhages,  whicli 
occur  on  the  free  surfaces  of  the  mucous  and  serous  membranes,  and  in  the  paren- 
chyma of  organs,  as  well  as  in  wounds.  The  blood  coagulates  with  difficulty,  and 
imperfectly. 

Transfusion  of  other  Fluids- — Other  substances  have  been  transfused. 
NoKMAL  Saline  Solution  (0*6  p.c.  NaCl)  aids  the  circulation  in  a  purely 
mechanical  way  (Goltz),  and  it  even  excites  the  circulation  (Kronecker,  Sander, 
Ott).  In  severe  anaemia  this  fluid  cannot  maintain  life  (Eulenburg  and  Landois). 
The  injection  of  Peptone,  even  in  moderate  amount,  is  dangerous  to  life,  as  it  causes 
paralysis  of  the  vessels.  The  injection  of  Milk  is  accompanied  with  danger ; 
fever  occurs  after  the  injection,  and  the  milk  globules  cause  the  occlusion  of  many 
vessels,  producing  subsequent  degenerations.  Fat  may  appear  in  the  urine, 
and  there  may  be  fatty  infiltration  of  the  urinary  tubules.  The  urine  contains 
sugar  and  albumin,  the  liver  cells  often  contain  fatty  granules,  and  the  weight  of 
the  body  diminishes.  If  too  large  a  quantity  of  milk  be  transfused,  death  occurs. 
When  unboiled  milk  is  injected,  numerous  bacteria  are  developed  in  the  blood 
(Schafer). 


The  Blood-Ulands. 


103.    The  Spleen. 

Structure. — The  spleen  is  covered  by  the  peritoneum,  except  at  the 
hihis.  Under  this  serous  covering  there  is  a  tough  thick  elastic 
fibrous  CAPSULE,  which  closely  invests  the  organ  and  gives  a  covering 
to  the  vessels  which  enter  or  leave  it  at  the  hilus,  so  that  fibrous  tissue 
is  carried  into  the  organ  along  the  course  of  the  vessels.  [The  capsule 
cannot  be  separated  without  tearing  the  splenic  pulp.]  Numerous 
TRABECUL.E  pass  into  the  spleen  from  the  deep  surface  of  the  capsule. 
These  trabeculse  branch  and  anastomose  so  as  to  produce  a  net-work 
or  sustentacular  tissue,  which  is  continuous  with  the  connective  tissue, 
prolonged  inwards  and  surrounding  the  blood-vessels  (Fig.  88).  Thus, 
the  connective  tissue  in  the  spleen,  as  in  other  viscera,  is  continuous 


TrabeculjB  of  the  spleen  of  a  cat  with  the  splenic  pulp 
washed  out — a,  trabecula ;  b,  vein. 


Fig.  89. 

Spleen  of  a  cat  injected 
with  gelatine,  show- 
ing the  adenoid  re- 
ticulum. 


throughout  the  organ.  In  this  way  an  irregular  dense  net-work  is 
formed,  comparable  to  the  meshes  of  a  bath-sponge.  [This  net-work  is 
easily  demonstrated  by  washing  out  the  pulp  lying  in  its  meshes  by 
means  of  a  stream  of  water,  when  a  beautiful  soft  semi-elastic  net-work 
of  rounded  and  flattened  threads  is  obtained.] 

The  Capsule  is  composed  of  interlacing  bundles  of  connective  tissue 


204  BLOOD-VESSELS  OF  THE  SPLEEN. 

mixed  with  numerous  fine  fibres  of  elastic  tissue  and  some  non-striped 
muscular  fibres. 

Reticulum. — Within  the  meshes  of  the  trabecular  framework  there  is 
dispersed  a  very  delicate  net-work  (reticulum)  of  adenoid  tissue  (Billroth), 
which,  with  the  other  coloured  elements  that  fill  up  the  meshes,  con- 
stitute the  splenic  pulp  (Fig.  89).  The  reticulum  is  continuous  with  the 
fibres  of  the  trabeculse.  [If  a  fine  section  of  the  spleen  be  "  pencilled  " 
in  water,  so  as  to  remove  the  cellular  elements,  the  preparation  presents 
much  the  same  characters  as  a  section  of  a  lymph-gland  similarly 
treated,  viz.,  a  very  fine  net-work  of  adenoid  tissue,  continuous  with, 
and  surrounding  the  walls  of,  the  blood-vessels.  The  spaces  of  this 
tissue  (His)  are  filled  with  lymph  and  blood-corpuscles.] 

The  Pulp  is  a  dark  reddish-coloured  semi-fluid  material,  which  may 
be  squeezed  or  washed  out  of  the  meshes  in  which  it  lies.  It  contains 
a  large  number  of  coloured  blood-corpuscles,  and  becomes  brighter 
when  it  is  exposed  to  the  action  of  the  oxygen  of  the  air. 

Blood-Vessels  and  Malpighian  Corpuscles The  large  splenic  artery 

splits  up  into  several  branches  before  it  enters  the  spleen,  and  it  is  accom- 
panied in  its  course  by  the  veiu.  Both  vessels  and  their  branches  are 
enclosed  in  a  fibrous  sheath,  which  becomes  continuous  with  the  trabeculse. 
The  smaller  branches  of  the  artery  gradually  lose  this  fibrous  investment, 
and  each  one  ultimately  divides  into  a  group  or  pencil  of  arterioles  (PENI- 
CiLLi)  which  do  not  anastomose  with  each  other.  [Thus  each  branch  is 
termijial — a  condition  which  is  of  great  importance  in  connection  with 
the  pathology  of  embolism  or  infarction  of  the  vessels  of  the  spleen.]  At 
the  points  of  division  of  the  branches  of  the  artery,  or  scattered  along 
their  course,  are  small  oval  or  globular  masses  of  adenoid  tissue  about 
the  size  of  a  small  millet  seed  (-J^^  to  -J-  inch  in  diameter) — the  ]VIAL- 
PiGHiAN  CORPUSCLES.  [These  bodies  are  visible  to  the  naked  eye  as 
small,  round,  or  oval  white  structures,  about  the  size  of  millet  seed,  in 
a  section  of  a  fresh  spleen.  They  are  very  numerous — [7,000  in  man 
(Sappey)] — and  are  readily  detected  in  the  dark  reddish  pulp. 
We  must  be  careful  not  to  mistake  sections  of  the  trabeculse  for 
them.  These  corpuscles  consist  of  adenoid  tissue,  whose  meshes 
are  loaded  with  lymph-corpuscles,  and  they  present  exactly  the  same 
structure  as  the  solitary  follicles  of  the  intestine  (compare  Lymphatic 
Glands). 

[They  are  just  small  lymphatic  accumulations  around  the  arteries — 
periarterial  masses  of  adenoid  tissue  similar  to  those  masses  that  occur 
in  a  slightly  different  form  in  other  organs,  e.g.,  the  lungs.  In  a 
section  of  the  spleen  the  artery  may  pass  through  the  centre  of 
the  mass  or  through  one  side  of  it,  and  in  some  cases  the  tissue 
is  collected  unequally  on  opposite  sides  of  the  vessel,  so  that  it  is 


BLOOD-VESSELS   OF   THE   SPLEEN. 


205 


lob-sided.  They  are  not  surrounded  by  any  special  envelope.  In 
some  animals  the  lymphatic 
tissue  is  continued  for  some 
distance  along  the  small 
arteries,  so  that  to  some  ex- 
tent it  resembles  a  peri- 
vascular sheath  of  adenoid 
tissue  (W.  Miiller,  Schweig- 
ger-Seidel).  In  a  well  injec- 
ted spleen,  a  few  fine  capillaries 
may  be  found  within  these 
corpuscles  (Sanders).  The 
capillaries  distributed  in  the 
substance  of  the  Malpighian 
corpuscle  (Fig.  90)  form  a 
net-work,  and  ultimately  pour  ^ig-  90. 

their  blood  into  the  spaces  in    Malpighian  corpuscle  of  the  spleen  of  a  cat 
the  pulp.   According  to  Eobin  injected  -  a,     artery    around     which    the 

,  -r  , ,  1  corpuscle  is  placed ;  h,  meshes  of  the  puli) 

and  Legros,  these  vessels  are        -.^^.^^e^.   ,,  the   artery  of  the   corpuscle 
comparable  to  the  vasa  vaso-  ramifying  in  the  lymphatic  tissue  composing 

rum   of   other    blood-vessels.  it-     The  clear  space  around  the  corpuscle  is 

According     to    Cadiat,    the        the  lymphatic  sinus, 
corpuscles  are  separated  from  the  splenic  pulp  by  a  lymphatic  sinus, 
which  is  traversed  by  efferent  capillaries  passing  to  the  pulp  (Fig.  90).] 

Connection  of  Arteries  and  Veins. — It  is  very  difficult  to  determine 
what  is  the  exact  mode  of  termination  of  the  arteries  within  the  spleen, 
more  especially  as  it  is  extremely  difficult  to  inject  the  blood-vessels  of 
the  spleen.  According  to  Stieda,  W.  Miiller,  Peremeschko,  and  Klein, 
the  fine  "capillary  arteries"  formed  by  the  division  of  the  small 
arteries  do  not  open  directly  into  the  capillary  veins,  but  the  connec- 
tion between  the  arteries  and  veins  is  by  means  of  the  "  intermediary 
intercellular  spaces''  of  the  reticulum  of  the  spleen,  so  that  according  to 
this  view,  there  is  no  continuous  channel  lined  throughout  by  epithelium 
connecting  these  vessels  one  with  another.  Thus  the  blood  of  the 
spleen  flows  into  the  spaces  of  the  adenoid  reticulum  just  as  the  lymph- 
stream  flows  through  the  spaces  in  a  lymph-gland.  According  to 
Billroth  and  KolUker,  a  closed  blood-channel  actually  does  exist 
between  the  capillary  arteries  and  the  veins,  consisting  of  dilated 
spaces  (similar  to  those  of  erectile  tissue).  These  intermediary  spaces 
are  said  to  be  completely  lined  by  spindle-shaped  einthelium,  which 
abuts  externally  on  the  reticulum  of  the  pulp.  [According  to  Frey, 
owing  to  the  walls  of  the  terminal  vessels  being  incomplete,  there 
being  clefts  or  spaces  between  the  cells  composing  them,  the  blood 


206  LYMPHATICS  AND   NERVES   OF  THE  SPLEEN. 

passes  freely  into  spaces  of  the  adenoid  tissue  of  the  pulp  "  in  the  same 
way  as  the  water  of  a  river  finds  its  way  amongst  the  pebbles  of  its 
bed,"  these  "intermediary  passages"  being  bounded  directly  by  the 
cells  and  fibres  of  the  net-work  of  the  pulp.  From  these  passages  the 
venous  radicles  arise.  At  first,  their  walls  are  imperfect  and  cribri- 
form, and  they  often  present  peculiar  transverse  markings  due  to  the 
circular  disposition  of  the  elastic  fibres  of  the  reticulum.  The  small 
veins  have  at  first  a  different  course  from  the  arteries.  They  anasto- 
mose freely,  but  they  soon  become  ensheathed,  and  accompany  the 
arteries  in  their  course.] 

Elements  of  the  Pulp. — The  morphological  elements  are  very 
various — (1.)  Lymph  corpuscles  of  various  sizes,  sometimes  partly 
swollen,  and  at  other  times  with  granular  contents,  (2.)  Red  blood- 
corpuscles.  (3.)  Transition  forms  between  1  and  2  [although  this  is 
denied  by  some  observers  (§  7  C)].  (4.)  Cells  containing  red  blood- 
corpuscles  and  pigment  granules.  [These  cells  exhibit  amoeboid  move- 
ments.]    (Compare  §  8.) 

[The  Lsnnphatics  undoubtedly  arise  within  the  spleen.  The  lym- 
phatics which  leave  the  spleen  are  not  numerous  (KoUiker).  There 
are  two  systems — a  superficial,  capsular,  and  trabecular  system ;  and  a 
peri-vascular  set.  The  superficial  lymphatics  in  the  capsule  are  rather 
more  numerous.  Some  of  them  seem  to  communicate  with  the 
lymphatics  within  the  organ  (Tomsa,  Kolliker).  In  the  horse's  spleen, 
they  communicate  with  the  lymphatics  in  the  trabeculse,  and  with  the 
peri-vascular  lymphatics.  The  exact  mode  of  origin  of  the  peri-vascular 
system  is  unknown,  but  in  part  at  least  it  begins  in  the  spaces  of 
the  adenoid  tissue  of  the  Malpighian  corpuscles  and  peri-vascular 
adenoid  tissue,  and  runs  along  the  arteries  towards  the  hilus.  There 
seem  to  be  no  afferent  lymphatics  in  the  spleen  such  as  exist  in  a 
lymphatic  gland.] 

The  Nerves  of  the  spleen  are  composed  for  the  most  part  of  non- 
meduUated  nerve-fibres,  and  run  along  with  the  artery.  Their  exact 
mode  of  termination  is  unknown,  but  they  probably  go  to  the  blood- 
vessels and  to  the  muscular  tissue  in  the  capsule  and  trabeculse.  [They 
are  well  seen  in  the  spleen  of  the  ox,  and  in  their  course  very  small 
ganglia  placed  wide  apart,  have  been  found  by  Eemak  and  W.  Stirling.] 

Chemical  Composition,— Several  of  the  more  highly  oxidised  stages  of  albu- 
minous bodies  exist  in  the  spleen.  Besides  the  ordinary  constituents  of  the  blood, 
there  exist :— leucin,  tyrosin,  xanthin,  hypoxanthin ;  also  lactic,  butyric  acetic, 
formic,  succinic,  and  uric  acids,  and  perhaps  glycero-phosphoric  acid  (Salkowski) ; 
Cholesteriu,  a  glutin-like  body,  inosite,  a  pigment  containing  iron,  and  even  free 
iron  oxide  (Nasse).  The  ash  is  rich  in  phosphoric  acid  and  iron — poor  in  chlorine 
compounds.     The  splenic  juice  is  alkaline  in  reaction;  the  specific  gravity  of  the 


Functions  oi'  the  spleen.  207 

spleen  =  1059  -  1066,    [The  watery  extract  of  the  spleen  contains  a  proteid  combined 
with  iron.] 

The  Functions  of  tlic  spleen  are  obscure,  but  Ave  know  some  facts  on 
which  to  form  a  theory.  [The  spleen  differs  from  other  organs  in  that 
no  very  apparent  effect  is  produced  by  it,  so  that  we  must  determine 
its  uses  in  the  economy  from  a  consideration  of  such  facts  as  the  follow- 
ing— (1.)  The  effects  of  its  removal  or  extirpation.  (2.)  The  changes 
which  the  blood  undergoes  as  it  passes  through  it.  (3.)  Its  chemical 
composition.  (4.)  The  results  of  experiments  upon  it.  (5.)  The 
effects  of  diseases.] 

(1.)  Extirpation. — The  spleen  may  be  removed  from  an  animal 
without  the  organism  suffering  any  very  obvious  change  (Galen).  The 
human  spleen  has  been  successfully  removed  by  Koberle,  P6an, 
Zacaralla  (1849),  and  others.  As  a  result  (compensatory  ?)  the  lym- 
phatic glands  enlarge,  but  not  constantly,  while  the  blood-forming 
activity  of  the  red  marrow  of  bone  is  increased.  Small  brownish-red 
patches  were  observed  in  the  intestines  of  frogs  after  extirpation  of  the 
spleen.  These  new  formations  are  regarded  by  some  observers  as  com- 
pensatory organs.  Tizzoni  asserts  that  new  splenic  structures  are 
formed  in  the  omentum  (horse,  dog)  after  the  destruction  of  the 
parenchyma  and  blood-vessels  of  the  spleen.  The  spleen  is  absent 
extremely  seldom  (Meinhard,  Koch,  and  Wachsmuth).  [Schindeler 
found  that  animals  after  extirpation  of  the  spleen  became  "very 
ravenous,  but  there  was  no  other  marked  symptom.] 

Schiff  stated  that  after  extirpation  of  the  spleen,  the  pancreatic  juice  failed  to 
digest  proteids.  The  evidence  in  support  of  this  statement  is  unsatisfactory,  and 
Mosler  afhrms  that  this  operation  has  no  effect  either  on  gastric  or  pancreatic  diges- 
tion. Heidenhain  also  found  a  similar  negative  result.  The  operation  ought  to 
be  performed  on  young  animals,  as  old  animals  often  succumb  to  it. 

(2.)  According  to  Gerlach  and  Funke  the  spleen  is  a  BLOOD-FORMING 
GLAND.  As  already  mentioned  (p.  20)  the  blood  of  the  splenic  vein 
contains  far  more  colourless  corpuscles  than  the  blood  of  the  splenic 
artery.  Many  of  these  corpuscles  undergo  fatty  degeneration,  and 
disappear  in  the  blood-stream  (Yirchow).  That  colourless  blood-cor- 
puscles are  formed  within  the  spleen  seems  to  be  proved  by  the 
enormous  number  of  these  corpuscles  which  are  found  in  the  blood 
in  cases  of  hyperplasia  of  the  spleen  or  leukaemia  (Bennett,  1852, 
Virchow).  Bizzozero  and  Salvioli  found  that  several  days  after  severe 
haemorrhage,  the  spleen  became  enlarged,  and  its  parenchyma  contained 
numerous  red  nucleated  hsemato-blasts. 

According  to  SchifF,  extirpation  of  the  spleen  has  no  effect,  either  upon  the 
absolute  or  relative  number  of  coloured  or  colourless  corpuscles.  [According  to 
the   more  accurate   observations   of  Picard  and  Malassez,  there  ig  a  temporary 


208  FUNCTIONS   OF  THE   SPLEEN. 

diminution  of  the  coloured  blood-corpusclea  and  their  hsemoglobin,  after  extirpa- 
tion of  the  spleen.] 

(3.)  Other  observers  (Kolliker  and  Ecker)  regard  the  spleen  as  an 
organ  in  which  coloured  blood-corpuscles  are  destroyed,  and  they 
consider  the  large  protoplasmic  cells  containing  pigment  granules  (p,  1 6) 
as  a  proof  of  this.  According  to  the  observations  of  von  Kusnetzow, 
these  structures  are  merely  lymph-corpuscles,  which,  in  virtue  of  their 
amoeboid  movements,  have  entangled  coloured  blood-corpuscles.  [Such 
corpuscles  exhibit  similar  properties  when  placed  upon  a  warm  stage.] 
Similar  cells  occur  in  extravasations  of  blood  (Virchow).  The  coloured 
blood-corpuscles  within  the  lymph-cells  gradually  become  disintegrated, 
and  give  rise  to  the  production  of  granules  of  hsematin  and  other 
derivatives  of  hsemoglobin.  Hence,  the  spleen  contains  more  iron  than 
corresponds  to  the  amount  of  blood  present  in  it.  When  we  con- 
sider that  the  spleen  contains  a  large  number  of  extractives  derived 
from  the  decomposition  of  proteids,  it  is  very  probable  that  coloured 
blood-corpuscles  are  destroyed  in  the  spleen.  Further,  the  juice  of  the 
spleen  contains  salts  similar  to  those  that  occur  in  the  red  blood- 
corpuscles. 

The  blood  of  the  spleen  is  said  to  undergo  other  changes,  but  the  following 
statements  must  be  accepted  with  caution  :  —The  blood  of  the  splenic  vein  contains 
inore  water  and  fibrin  ;  its  red  blood-corpuscles  are  smaller,  brighter,  less  flattened, 
more  resistant,  and  do  not  form  rouleaux  ;  its  hsemoglobin  crystallises  more  easily, 
and  there  is  a  larger  proportion  of  O  during  digestion. 

[It  would  thus  appear  that  the  spleen  has  a  very  direct  relation 
to  the  blood;  that  coloured  blood-corpuscles  undergo  disintegration, 
and  that  colourless  corpuscles  are  manufactured  within  it.] 

(4.)  Contraction. — In  virtue  of  the  plain  muscular  fibres  in  its 
capsule  and  trabeculse,  the  spleen  undergoes  variations  in  its  volume 
(Kolliker).  Stimulation  of  the  spleen  (Rud.  Wagner,  1849)  or  its 
nerves,  by  cold,  electricity,  quinine,  eucalyptus,  ergot  of  rye,  and  other 
"  splenic  reagents  "  (Hosier)  causes  it  to  contract^  whereby  it  becomes 
paler,  and  its  surface  may  even  appear  granular,  Aftei'  a  meal, 
the  spleen  increases  in  size,  and  it  is  usually  largest  about  five 
hours  after  digestion  has  begun — i.e.,  at  a  time  when  the  digestive 
organs  have  almost  finished  their  work,  and  have  again  become  less 
vascular.  After  a  time  it  regains  its  original  volume.  For  this  reason 
the  spleen  was  formerly  regarded  as  an  apparatus  for  regulating  the 
amount  of  blood  in  the  digestive  organs. 

[The  congestion  of  the  spleen  after  a  meal  is  more  probably  related 
to  the  formation  of  new  colourless  corpuscles  than  to  the  destruction  of 
red  corpuscles.     It  may  be,  however,  that  some  of  the  products  of 


CONTRACTION   OF  THE   SPLEEN. 


209 


digestion  are  partially  acted  upon  in  the  spleen,  and  undergo  further 
change  in  the  liver.] 

There  is  a  relation  between  the  size  of  the  spleen  and  that  of  the 
liver,  for  it  is  found  that  when  the  spleen  contracts — e.g.,  by  stimulation 
of  its  nerves — the  liver  becomes  enlarged  as  if  it  were  injected  with 
more  blood  than  usual  (Drosdow  and  Botschetschkarow). 

[Oncograph. — Botkin,  and  more  recently  Eoy,  have  studied  various 
conditions  which  affect  the  size  of  the  spleen.  Eoy's  observations 
are  most  important.  He  enclosed  the  spleen  of  a  living  animal  (dog) 
in  a  box  with  rigid  walls,  and  filled  mth  oil  after  the  manner  of  the 
plethysmograph  (§  101).  Any  variations  in  the  size  of  the  organ 
caused  a  variation  in  the  amount  of  oil  within  the  box,  and  these 
variations  were  recorded.  This  instrument  Eoy  termed  an  "  onco- 
graph" {oyxog,  volume).  The  blood-pressure  was  recorded  at  the 
same  time. 

Eoy  finds  that  the  circulation  through  the  spleen  is  peculiar,  and 
that  it  is  not  due  to  the  blood-pressure  within  the  arteries,  but  is 
carried  on  chiefly  by  a  rhythmical  contraction  of  the  muscular  fibres  of 
the  capsule  and  trabeculse.  The  spleen  undergoes  very  regular  rhyth- 
mical contractions  (systole)  and  dilatations   {diastole).     This  alternation 


/  \-.Sple 


V     Blood-pressare  I 


^^wA/AAW^M^'^n'V' 


'Vy^7  '  y       I 


Atscissa  of  Blood-pressure- cuvv^e  2  secf   intpr/als 


Fig.  91. 


Tracing  of  a  splenic  curve,  reduced  oue-half,  taken  with  the  oncograph.  The  upper 
line  with  large  waves  is  the  splenic  curve,  each  ascent  corresponds  to  an 
increase,  and  each  descent  to  a  diminution  in  the  volume  of  the  spleen.  The 
curve  beneatli  is  a  blood-pressure  tracing  from  the  carotid  artery.  The  lowest 
line  indicates  the  time,  the  interruptions  of  the  marker  occurring  every  two 
seconds.  The  vertical  lines,  a  and  b,  give  the  relative  positions  of  the  lever 
point  of  the  oncograph,  and  of  the  point  of  the  recording  style  of  the  kymograph 
respectively  (Roy). 

14 


210  INFLUENCE   OF  NERVES   ON  THE   SPLEEN. 

of  systole  and  diastole  may  last  for  hours,  and  the  two  events  together 
occupy  about  one  minute  (Fig.  91).  Changes  in  the  arterial  blood- 
pressure  have  comparatively  little  influence  on  the  volume  of  the  spleen. 
The  rhythmical  contractions,  although  modified,  still  go  on  after  section 
of  the  splenic  nerves.  This  would  seem  to  indicate  that  the  spleen  has 
an  independent  (nervous)  mechanism  within  itself  causing  its  move- 
ments.] 

Influence  of  Nerves. — Section  of  the  splenic  nerves  causes  an 
increase  in  the  size  of  the  spleen ;  and  when  the  nerves  at  the  hilum 
are  extirpated  it  swells  and  assumes  a  deep  purple  colour.  The  nerves 
have  their  centre  in  the  medulla  oblongata,  and  so  far  they  are  com- 
parable to  vaso-motor  nerves.  Stimulation  of  the  medulla  oblongata, 
either  directly  or  by  means  of  asphyxiated  blood,  causes  contraction  of 
the  spleen  [hence,  the  spleen  is  "small  and  contracted"  in  death 
from  asphyxia.]  The  fibres  proceed  down  the  cord,  and  are  probably 
joined  by  other  fibres  derived  from  ganglion  cells  lying  opposite  the 
first  to  the  fourth  cervical  vertebrae,  which  cells  also  act  on  the  spleen. 
The  fibres  leave  the  cord  in  the  dorsal  region,  enter  the  left  splanchnic, 
pass  through  the  semi-lunar  ganglion,  and  thus  reach  the  splenic  plexus 
(Jaschkowitz.)  Stimulation  of  the  peripheral  ends  of  these  nerves 
causes  contraction  of  the  spleen,  and  so  does  cold  applied  to  the  spleen 
directly  or  over  the  region  of  the  organ.  In  this  last  case  the  result 
is  brought  about  reflexly.  Section  or  paralysis  of  these  nerves  causes 
dilatation,  and  so  does  curara  or  continued  narcosis  (Bulgak).  [Botkin 
found  that  the  application  of  the  induced  current  to  the  skin  over  the 
spleen,  in  a  case  of  leukaemia,  caused  well-marked  contraction  of  the 
spleen  in  aU  its  dimensions ;  the  spleen  becoming  firmer,  and  its  surface 
more  in-egular.  The  result  lasted  much  longer  than  the  duration  of 
the  stimulus.  The  same  occurred  in  a  case  of  enlarged  lymphatic 
glands.  After  a  time  the  organ  began  to  enlarge.  After  every  stimu- 
lation the  number  of  colourless  corpuscles  in  the  blood  increased,  and 
the  condition  of  the  patient  improved.] 

[There  is  a  popular  notion  that  the  spleen  is  influenced  by  the  condition 
of  the  nervous  system.  Botkin  found  that  depressing  emotions  in- 
creased its  size,  while  exhilarating  ideas  diminished  it.  The  causes  of 
these  changes  are  referable  not  only  to  changes  in  the  amount  of  blood 
in  the  spleen,  but  also  to  the  greater  or  less  degree  of  contraction  of 
its  muscular  tissue.  And  it  would  appear  that,  like  the  small  arteries, 
the  muscular  tissue  of  the  spleen  is  in  a  state  of  ionic  contraction.  The 
size  of  the  spleen  may  be  influenced  reflexly.  Thus,  Tarchanoff  found 
that  stimulation  of  the  central  end  of  the  vagus,  when  the  splanchnics 
were  intact,  caused  contraction  of  the  spleen,  while  stimulation  of  the 
central  end  of  the  sciatic  also  caused  contraction,  but  to  a  less  degree. 


INFLUENCE  OF  NERVES  ON  THE  SPLEEN.  211 

It  is  quite  certain  that  all  the  phenomena  are  not  due  to  the  action  of 
vaso-motor  nerves  on  the  splenic  blood-vessels.  There  is  a  certain 
amount  of  independent  action  of  the  muscular  fibres  of  the  organ,  and 
it  is  not  improbable  that  the  innervation  of  the  spleen  is  similar  to  the 
innervation  of  arteries,  and  that  it  has  a  motor  centre  in  the  cord 
capable  of  being  influenced  by  afferent  nerves,  and  sending  out  efferent 
impulses.] 

[Eoy  confirmed  most  of  these  results,  and  found  that  stimulation  of 
(1)  the  central  end  of  a  sensory  nerve,  (2)  of  the  peripheral  ends  of 
both  splanchnics,  (3)  of  the  peripheral  ends  of  both  vagi,  caused 
contraction  of  the  spleen.  But  even  after  section  of  the  splanchnics 
and  vagi,  stimulation  of  a  sensory  nerve  still  caused  contraction,  so 
that  there  must  be  some  other  channel  as  yet  unknown.  Boche- 
fontaine  found  that  electrical  stimulation  of  certain  parts  of  the  cortex 
cerebri  produced  contraction  of  the  spleen.]  Senswy  nerves  seem  to 
occur  only  in  the  peritoneum  covering  the  spleen. 

Pressui'e  on  the  splenic  vein  causes  enlargement  of  the  spleen  (Hosier) ;  hence, 
increased  pressure  in  this  vein  (congestion  of  the  portal  vein,  cessation  of  hfemor- 
rhoidal  and  menstrual  discharges)  also  causes  its  enlargement.  With  regard  to  the 
action  of  '■^splenic  reagents,"  such  as  Quinine,  on  the  contraction  of  the  spleen, 
Binz  is  of  opinion  that  this  drug  retards  the  formation  of  the  colourless  blood-cor- 
puscles, so  that  its  chief  function  is  interfered  with  and  the  organ  becomes  less 
vascular.  It  is  not  definitely  decided,  however,  whether  it  is  contraction  or  dilata- 
tion of  the  spleen  that  alters  the  proportion  of  red  and  white  corpuscles  in  the  blood. 

Splenic  Tumours. — The  increase  in  size  of  the  spleen  in  various  diseases  early 
attracted  the  attention  of  physicians.  The  healthy  sjileen  undergoes  several  varia- 
tions in  volume  during  the  com-se  of  a  day,  corresponding  with  the  varying  activity 
of  the  digestive  organs.  In  this  respect  the  spleen  resembles  the  arteries.  In 
many  fevers  the  spleen  becomes  greatly  enlarged,  probably  due  to  paralysis  of  its 
nerves.  It  is  greatly  increased  in  intermittent  fever  or  ague,  and  often  during 
the  course  of  typhus.  When  it  becomes  abnormally  enlarged,  and  remains  so  after 
repeated  attacks  of  ague,  it  is  greatly  hypertrophied  and  constitutes  "ague  cake." 
In  cases  of  splenic  leukcemia  it  is  greatly  enlarged,  and  at  the  same  time  there  is  a 
great  increase  in  the  number  of  colourless  corpuscles  in  the  blood,  and  also  a 
decrease  of  the  coloured  ones  (p.  23). 


II.  The  Thymus. 

During  fcetal  life  this  gland  is  largely  developed,  and  it  increases  during  the  tirst 
two  or  three  years  of  life,  remaining  stationary  until  the  tenth  or  fourteenth  year, 
when  it  begins  to  atrophy  and  undergo  fatty  degeneration.  [The  degeneration 
begins  at  the  outer  part  of  each  lobule  and  progress  inwards  (His).] 

Structure. — ["  It  consists  of  an  aggregation  of  lymph-follicles  (resembling  the 
glands  of  Peyer)  or  masses  of  adenoid  tissue  held  together  by  a  framework  of  con- 
nective tissue  which  contains  blood-vessels,  lymphatics,  and  a  few  nerves  (Fig.  92). 
Th.Q  framework  of  connective  tissue  gives  off  septa  which  divide  the  glaudinto  lobes, 
these  being  farther  subdivided  by  finer  septa  into  lobules,  the  lobules  being  separated 


212 


THE  THYMtTS. 


by  fine  intra-lobular  lamellse  of  connective  tissue  into  follicles  (0"5-l'5  mm.)- 
These  follicles  make  up  the  gland  substance,  and  they  are  usually  polygonal  when 
seen  in  a  section.  Each  follicle  consists  of  a  cortical  and  a  medullary  part,  and  the 
matrix  or  framework  of  both  consists  of  a  fine  adenoid  reticulum  whose  meshes 
are  filled  with  lymph-corpuscles"  (Fig.  93,  a).]  Many  of  these  corpuscles 
exhibit  various  stages  of  disintegration.  In  the  medulla  are  found  the  concentric 
corpuscles  of  Hassall.  ["  They  consist  of  a  central  granular  part,  around  which  are 
disposed  layers  of  flattened  nucleated  endothelial  cells  arranged  concentrically. 
When  seen  in  a  section  they  resemble  the  '  cell-nests '  of  epithelioma  (Fig.  93,  b). 


Fig.  92. 

Section  of  the  thymus  gland  of  a  cat,  showing 
one  complete  lobule  with  an  outer  cortical 
part,  a  centre,  b,  and  parts  of  adjoining 
lobules  —  a,  lymphoid  tissue  ;  c,  blood- 
vessels injected  ;  d,  connective  tissue. 


Fig.  93. 

Elements  of  the  thymus  (  x  300)— 
a,  lymph-corpuscles  ;  b,  con- 
centric corpuscle  of  Hassall. 


They  have  also  been  compared  to  similar  bodies  which  occur  in  the  prostate. 
They  are  most  numerous  when  the  gland  undergoes  its  retrograde  metamorphosis. "] 

Simon,  His,  and  others  described  a  convoluted  blind  canal,  the  "  central  canal," 
as  occurring  within  the  gland,  and  on  it  the  follicles  were  said  to  be  placed.  Other 
observers,  Jendrassik  and  Klein,  either  deny  its  existence  or  regard  it  merely  as  a 
lymphatic  or  an  artificial  product.  Numerous  fine  lymphatics  penetrate  into  the 
interior  of  the  organ,  and  many  are  distributed  over  its  surface,  but  their  mode  of 
origin  is  unknown.  [They  seem  to  be  channels  through  which  the  lymph-cor- 
puscles are  conveyed  away  from  the  gland.]  Numerous  blood-vessels  are  also  dis- 
tributed to  the  septa  and  follicles  (Fig  92,  c). 

Chemical  Composition. — Besides  gelatin,  albumin,  soda-albumin,  there  are 
sugar  and  fat,  leucin,  xanthin,  hypoxanthin,  formic,  acetic,  butyric,  and  succinic 
acids.  Potash  and  phosphoric  acid  are  more  abundant  in  the  ash  than  soda, 
calcium,  magnesium  (?  ammonium),  chlorine,  and  sulphuric  acid  (v.  Gorup- 
Besanez). 

[Function. — As  long  as  it  exists,  it  seems  to  perform  the  functions  of  a  true 
lymph-gland.  This  view  is  supported  by  the  fact  that  in  reptiles  and  amphibians, 
which  do  not  possess  lymph-glands,  the  thymus  remains  as  a  permanently  active 
organ.  That  the  thymus  forms  colourless  corpuscles  was  first  maintained  by 
Hewson,  and  confirmed  by  His  and  Jendrassik.    Extirpation  (Friedleben)  gave  few 


THE   THYKOID, 


213 


positive  results,  but  chemical  investigation  shows  that  the  parenchyma  contains  a 
large  number  of  products  indicating  considerable  metabolic  activity.  The  volume 
of  the  gland  undergoes  variations  both  in  health  and  disease.] 


III.  The  Thyroid. 


structure, — In  a  connective  tissue  net-work  rich  in  cells  there  lie  numerous 
completehj  closed  sacs  {004:— O'l  mm.  in  diameter),  which  in  the  embryo  and  the 
newly-born  animal  are  composed  of  a  membrana  propria  lined  by  a  single  layer  of 
nucleated  cubical  cells  (Fig.  94).  The  sacs  contain  a  transparent,  viscid,  albuminous 
fluid.  [Not  unfrequently  the 
sacs  contain  many  coloured 
blood- corpuscles  (Baber).  As 
in  other  glands,  there  are 
lobes  cind  lobules.]  Each  sac 
is  surrounded  by  a  plexus  of 
capillaries  which  do  not  pene- 
trate the  membrana  propria. 
There  are  also  numerous 
lymphatics.  At  an  early 
period  the  sacs  dilate,  their 
cellular  lining  atrophies,  and 
their  contents  undergo  colloid 
degeneration.  When  the 
gland  vesicles  are  greatly 
enlarged,  "goitre"  is  pro- 
duced. 

The  Chemical  Composi- 
tion of  this  gland  has  not 
been  much  investigated.  In 
addition  to  the  ordinary  con- 
stituents, leucin,  xanthin, 
sarkin,  lactic,  succinic,  and 
volatile  fatty  acids  have  been 
found. 

Functions. — Its  functions  are  quite  unknown 
for  regulating  the  blood  supply  to  the  head  (?). 


Fig.  94. 

Section  of  the  thyroid  gland  (  x  250) — a,  small 
closed  vesicles  lined  by  low  columnar  epithe- 
lium ;  b,  colloid  masses  distending  the  vesicles ; 
c,  connective  tissue  between  the  vesicles. 


Perhaps  it  may  be  an  apparatus 
It  becomes  enlarged  in  Basedow's 
disease,  in  which  there  is  great  palpitation,  as  well  as  protrusion  of  the  eyeball 
[Exophthalmos],  which  seem  to  depend  upon  a  simultaneous  stimulation  of  the 
accelerating  nerve  of  the  heart,  and  the  sympathetic  fibres  for  the  smooth  muscles 
in  the  orbital  cavity  and  the  eyelids,  as  well  as  of  the  inhibitory  fibres  of  the 
vessels  of  the  thyroid.  In  many  localities  it  is  common  to  find  swelling  of  the 
thyroid  constituting  goitre,  which  is  sometimes,  but  far  from  invariably,  associated 
with  idiocy  and  cretinism. 


IV.  The  Supra-Renal  Capsules. 

structure. — These  organs  are  invested  by  a  thin  capsule  which  sends  processes 
into  the  interior  of  the  organ.  They  consist  of  an  outer  (broad)  or  cortical  layer 
and  an  inner  (narrow)  or  medullary  layer.  The  former  is  yellowish  in  colour,  firm 
and  striated,  while  the  latter  is  softer  and  deeper  in  tint.  In  the  outermost  zone 
of  the  corteoi  (Fig.  95,  b),  the  trabeculas  form  polygonal  meshes  which  contain  the 


214 


THE   SUPRA-RENAL  CAPSULES. 


cells  of  the  gland  substance  ;  in  the  broader  middle  zone,  the  meshes  are  elongated 
and  the  cells  filling  them  are  arranged  in  columns  radiating  outwards.  Here  the 
cells  are  transparent  and  nucleated,  often  containing  oil  globules  ;  in  the  innermost 

narrow  zone  the  polygonal  arrangement 
prevails,  and  the  cells  often  contaui 
yellowish-brown  pigment.  In  the  medulla 
(c)  the  stroma  forms  a  reticulum  contain- 
ing groups  of  cells  of  very  irregular  shape. 
Numerous  blood-vessels  occur  in  the 
gland,  especially  in  the  cortex,  [The 
nerves  are  extremely  numerous,  and  are 
derived  from  the  renal  and  solar  plexuses. 
Many  of  the  fibres  are  medullated.  After 
they  enter  the  gland,  numerous  ganghonic 
cells  occur  in  the  plexuses  which  they  form. 
Indeed,  some  observers  regard  the  cells  of 
the  medulla  as  nervous.  Undoubtedly, 
n\im.erous,multipolarnerve-celk  exist  with- 
in the  gland.]  —  (Eberth,  Creighton,  v. 
Brunn). 

Chemical  Composition.— The  supra- 

renals  contain  the  constituents  of  connec- 
tive-tissue and  nerve-tissue;  also  leucin, 
hypoxanthin,  benzoic,  hippuric,  andtauro- 
cholic  acids,  taurin,  inosit,  fats,  and  a  body 
which  becomes  pigmented  by  oxidation. 
Amongst  inorganic  substances  potash  and 
phosphoric  acid  are  most  abundant. 

The  fanction  of  the  supra-renal  bodies 
is  quite  unknown.  It  is  noticeable,  how- 
ever, that  in  Addison's  disease  ("bronzed 
skin ")  which  is  perhaps  primarily  a 
nervous  affection,  these  glands  have  fre- 
quently, but  not  invariably,  been  found 
to  be  diseased.  Owing  to  the  injury  to 
■  adjacent  abdominal  organs  extirpation  of 
these  organs  is  often,  although  not  always, 
fatal.  Brown- S^quard  thinks  they  may 
be  concerned  in  preventing  the  over-production  of  pigment  in  the  blood. 


Fig.  95. 

Section  of  a  human  supra-renal  capsule 
— a,  capsule ;  h,  gland  cells  of  the 
cortex  arranged  in  columns;  c, 
glandular  net-work  of  themeduUa; 
d,  blood-vessels. 


V.  Hypophysis  Cerebri— Coccygeal  and  Carotid 

Grlands. 


The  hjrpopliysis  cerebri,  or  pituitary  body,  consists  of  an  anterior  lower  or 
larger  lobe  partly  embracing  the  posterior  lower  or  smaller  lobe.  These  two  lobes 
are  distinct  in  theu'  structure  and  development.  The  posterio?-  lobe  is  a  part  of 
the  brain,  and  belongs  to  the  infundibulum.  The  nervous  elements  are  displaced 
by  the  ingrowth  of  connective-tissue  and  blood-vessels.  The  anterior  portion 
represents  an  inflected  and  much-altered  portion  of  ectoderm,  from  which  it  is 
developed.  It  contains  gland-like  structures,  with  connective-tissue,  lymphatics 
and  blood-vessels,  the  whole  being  surroimded  by  a  capsule.  According  to  Ecker 
and  Mihalkowicz,  it  resembles  the  supra-renal  capsule   in   its   structure,  while. 


COMPARATIVE  PHYSIOLOGY   OF  THE   CIRCULATION.  215 

according  to  other  observers,  in  some  animals  it  is  more  like  the  thyroid.     Its 
functions  are  entii-ely  imknown. 

Coccygeal  and  Caxotid  Glands.— The  former,  which  lies  on  the  tip  of  the 
coccyx,  is  composed,  to  a  large  extent,  of  plexuses  of  small  more  or  less  cavernous 
arteries,  supported  and  enclosed  by  septa  and  a  capsule  of  connective-tissue 
(Luschka).  Between  these  lie  polyhedral  granular  cells  arranged  in  net-works. 
The  carotid  gland  has  a  similar  structure  (j).  124).  Their  functions  are  quite 
unkno-\\Ti.  Perhaps  both  organs  may  be  regarded  as  the  remains  of  embryonal 
blood-vessels  (Arnold). 

104.  Comparative. 

The  heart  in  fishes  as  well  as  in  the  larvfe  of  amphibians  with  gills,  is  a  simple 
venous  heart  consisting  of  an  auricle  and  a  ventricle.  The  ventricle  propels  the 
blood  to  the  gills  where  it  is  oxygenated  (arterialised) ;  thence  it  passes  into  the  aorta 
to  be  distributed  to  all  parts  of  the  body,  and  returns  through  the  capillaries  of  the 
body  and  the  veins  to  the  heart.  The  amphibians  (frogs)  have  two  auricles  and 
one  ventricle.  From  the  latter  there  proceeds  one  vessel  which  gives  off  the  pul- 
monary arteries,  and  as  the  aorta  supplies  the  rest  of  the  body  M-ith  blood,  the 
veins  of  the  systemic  circulation  carry  their  blood  to  the  right  auricle,  those  of  the 
lung  into  the  left  auricle.  In  fishes  and  amphibians  there  is  a  dilatation  at  the 
commencement  of  the  aorta,  the  bulbus  arteriosus,  which  is  partly  provided  with 
strong  muscles.  The  reptiles  possess  two  separate  auricles,  and  two  imperfectly 
separated  ventricles.  The  aorta  and  pulmonary  artery  arise  separately  from  the 
two  latter  chambers.  The  venous  blood  of  the  systemic  and  pulmonary  circulations 
flows  separately  into  the  right  and  left  auricles,  and  the  two  streams  are  mixed  in  the 
ventricle.  In  some  reptiles  the  opening  in  the  ventricular  septum  seems  capable  of 
being  closed.  The  crocodile  has  two  quite  separate  ventricles.  The  lower  vertebrates 
have  valves  at  the  orifices  of  the  venje  cavae,  which  are  rudimentary  in  birds  and 
some  mammals.  All  birds  and  mammals  have  two  completely  separate  auricles 
and  two  separate  ventricles.  In  the  halicore  the  apex  of  the  ventricles  is  deeply 
cleft.  Some  animals  have  accessory  hearts,  e.g.,  the  eel  in  its  caudal  vein.  They 
are  very  probably  lymph-hearts  (Robin).  The  veins  of  the  wing  of  the  bat 
pulsate  (Schiff).  The  lowest  vertebrate,  amphioxus,  has  no  heart,  but  only  a 
rhj'thmically-contracting  vessel. 

Amongst  blood-glands  the  thymus  and  spleen  occur  tliroughout  the  vertebrata, 
the  latter  being  absent  only  in  amphioxus  and  a  few  fishes. 

Amongst  invertebrata  a  dosed  vascular  system,  with  pulsatile  movement, 
occurs  here  and  there,  e.g.,  amongst  echmodermata  (star-fishes,  sea-urchins,  holo- 
thurians)  and  the  higher  loorms.  The  insects  have  a  pulsating  "dorsal  vessel"  as 
the  central  organ  of  the  circulation,  which  is  a  contractile  tube  provided  with 
valves  and  dilated  by  muscular  action;  the  blood  being  propelled  rhythmically 
in  one  direction  into  the  spaces  which  lie  amongst  the  tissues  and  organs,  so  that 
these  animals  do  not  possess  a  closed  vascular  system.  The  mollusca  have  a 
heart  with  a  lacunar  vascular  system.  The  cephalopods  (cuttle-fish)  have  three 
hearts — a  simple  arterial  heart,  and  two  venous  simple  gill-hearts,  each  placed  at 
the  base  of  the  gills.  The  vessels  form  a  completelj^  closed  circuit.  The  lowest 
animals  have  either  a  pulsatile  vesicle,  which  propels  the  colourless  juice  into  the 
tissues  (infusoria),  or  the  vascular  apparatus  may  be  entirely  absent. 

105.  Historical  Retrospect. 

The  ancients  held  various  theories  regarding  the  movement  of  the  blood,  but  they 
knew  nothing  of  its  circulation.     According  to  Aristotle  (384  B.C. ),  the  heart,  the 


216  HISTORICAL  RETROSPECT  OF  THE  CIRCULATION. 

acropolis  of  the  body,  prepared  in  its  cavities  the  blood,  which  streamed  through 
the  arteries  as  a  nutrient  fluid  to  all  parts  of  the  body,  but  never  returned  to 
the  heart. 

"With  Herophilus  and  Erasistratus  (300  B.C.),  the  celebrated  physicians  of  the 
Alexandrian  school,  originated  the  erroneous  view  that  the  arteries  contain  air, 
which  was  supplied  to  them  by  the  respiration  (hence  the  name  artery).  They 
were  led  to  adopt  this  view  from  the  empty  condition  of  the  arteries  after  death. 
By  experiments  upon  animals,  Galen  disproved  this  view  (131-201  a.d.)— "  When- 
ever I  injured  an  artery,"  he  says,  "blood  always  flowed  from  the  wounded  vessel. 
On  tying  part  of  an  artery  between  two  ligatures,  the  part  of  the  artery  so 
included  is  always  filled  with  blood." 

Still,  the  idea  of  a  single  centrifugal  movement  of  the  blood  was  retained, 
and  it  was  assumed  that  the  right  and  left  sides  of  the  heart  communicated 
directly  by  means  of  openings  in  the  septum  of  the  heart  until  Vesalius  showed 
that  there  are  no  openings  in  the  septum.  Michael  Servetus  (the  Spanish  monk, 
burned  at  Geneva,  at  Calvin's  instigation,  in  1553)  discovered  the  pulmonary 
circulation.  Cesalpinus  confirmed  this  observation,  and  named  it  "  Circulatio." 
Fabricius  ab  Aquapendente  (Padua,  1574)  investigated  the  valves  in  the  veins 
more  carefully  (although  they  were  known  in  the  fifth  century  to  Theodoretus, 
Bishop  in  Syria),  and  he  was  acquainted  with  the  centripetal  movement  of  the 
blood  in  the  veins.  Up  to  this  time  it  was  imagined  that  the  veins  carried  blood  from 
the  centre  to  the  periphery,  although  Vesalius  was  acquainted  with  the  centripetal 
direction  of  the  blood-stream  in  the  large  venous  trunks.  At  length,  William 
Harvey,  who  was  a  pupil  of  Fabricius  (1604)  demonstrated  the  complete  circula- 
tion (1616-1619),  and  published  his  great  discovery  in  1628.  [For  the  history  of 
the  discovery  of  the  circulation  of  the  blood,  see  the  works  of  Willis  on  "W. 
Harvey,"  "Servetus  and  Calvin,"  those  of  Kirchner,  and  the  various  Harveian 
orations.] 

According  to  Hippocrates,  the  heart  is  the  origin  of  all  the  vessels ;  he  was 
acquainted  with  the  large  vessels  arising  from  the  heart,  the  valves,  the  chordae 
tendinise,  the  auricles,  the  closure  of  the  semi-lunar  valves.  Aristotle  was  the  first 
to  apply  the  terms  aorta  and  vense  cavae;  the  school  of  Erasistratus  used  the 
term  carotid,  and  indicated  the  functions  of  the  venous  valves.  In  Cicero  a  dis- 
tinction is  drawn  between  arteries  and  veins.  Celsus  mentions  that  if  a  vein  be 
struck  below  the  spot  where  a  ligature  has  been  applied  to  a  limb,  it  bleeds,  while 
Aretaeus  (50  a.b.)  knew  that  arterial  blood  was  bright  and  venous  dark.  Pliny 
(t  79  A.D.)  described  the  pulsating  fontanelle  in  the  child.  Galen  (131-203  a.d.)  was 
acquainted  with  the  existence  of  a  bone  in  the  septum  of  the  heart  of  large  animals 
(ox,  deer,  elephant).  He  also  surmised  that  the  veins  communicated  with  the 
arteries  by  fine  tubes.  The  demonstration  of  the  capillaries,  however,  was  only 
possible  by  the  use  of  the  microscope,  and  employing  this  instrument,  Malpighi 
(1661)  was  the  first  to  demonstrate  the  capillary  circulation.  Leuwenhoek  (1674) 
described  the  cainllary  circulation  more  carefully,  as  it  may  be  seen  in  the  web  of 
the  frog's  foot  and  other  transparent  membranes.  Blancard  (1676)  proved  the 
existence  of  capillary  passages  by  means  of  injections.  William  Cooper  (1697) 
proved  that  the  same  condition  exists  in  warm-blooded  animals,  and  Euysch  made 
similar  injections.  Stenson  (bom  1638)  established  the  muscular  nature  of  the 
heart,  although  the  Hippocratic  and  Alexandrian  schools  had  already  surmised  the 
fact.  Cole  proved  that  the  sectional  area  of  the  blood-stream  became  wider  towards 
the  capillaries  (1681).  Job.  Alfons  Borelli  (1608-1679)  was  the  first  to  estimate  the 
amount  of  work  done  by  the  heart. 


Physiology  of  Eespiration. 


The  Object  of  respiration  is  to  supply  the  oxygen  necessary  for  the 
oxidation  processes  that  go  on  in  the  body,  as  well  as  to  remove  the 
carbonic  acid  formed  within  the  body.  The  most  important  organs 
for  this  purpose  are  the  lungs.  There  is  an  outer  and  an  inner  respira- 
tion— the  former  embraces  the  exchange  of  gases  between  the  external 
air  and  the  blood-gases  of  the  respiratory  organs  (lungs  and  skin) — the 
latter,  the  exchange  of  gases  between  the  blood  in  the  capillaries  of  the 
systemic  circulation  and  the  tissues  of  the  bod3% 

[The  pulmonary  apparatus  consists  of  (1)  an  immense  number  of 
small  sacs — the  air-vesicles — filled  with  air,  and  covered  externally  by 
a  very  dense  plexus  of  capillaries ;  (2)  air-passages — the  nose,  pharynx, 
larynx,  trachea,  and  bronchi  communicating  with  (1) ;  (3)  the  thorax 
with  its  muscles,  acting  like  a  pair  of  bellows,  and  moving  the  air  within 
the  lungs.] 

106.  Structure  of  the  Air-Passages  and  Lungs. 

The  lungs  are  compound  tubular  (racemose  ?)  glands  which  separate  CO2  from 
the  blood.  Each  lung  is  provided  with  an  excretory  duct  (bronchus)  which  joins 
the  common  respiratory  passage  of  both  lungs — the  trachea. 

Trachea. — The  trachea  and  extra-pulmonary  bronchi  are  similar  in  structure. 
The  basis  of  the  trachea  consists  of  a  number  (16-20)  of  C-shaped  incom- 
plete cartilaginous  hoops  placed  over  each  other.  These  rings  consist  of 
hyaline  cartilage,  and  are  united  to  each  other  by  means  of  tough  fibrous  tissue 
containing  much  elastic  tissue,  the  latter  being  arranged  chiefly  in  a  longitudinal 
direction.  The  function  of  the  cartilages  is  to  keep  the  tube  open  under  varying 
conditions  of  pressure.  Pieces  of  cartilage  having  a  similar  function  occur  in  the 
bronchi  and  their  branches,  but  they  are  absent  from  the  bronchioles,  which  are 
less  than  1  mm.  in  diameter.  In  the  smaller  bronchi  the  cartilages  are  fewer  and 
scattered  more  irregularly.  [In  a  transverse  section  of  a  large  intra-pulmonary 
bronchus,  two,  three,  or  more  pieces  of  cartilage,  each  invested  by  its  peri- 
chondrium, may  be  found.]  At  the  points  of  bifurcation  of  the  bronchi,  the 
cartilages  assume  the  form  of  irregular  plates  embedded  in  the  bronchial  wall. 

An  external  fibrous  layer  of  connective-tissue  and  elastic  fibres  covers  the 
trachea  and  the  extra-pulmonary  bronchi  externally.  Towards  the  oesophagus,  the 
elastic  elements  are  more  numerous,  and  there  are  also  a  few  bundles  of  plain 
muscular  fibres  arranged  longitudinally.  Within  this  layer  there  are  bundles  of 
non-striped  muscular  fibres  which  pass  transverselj'  between  the  cartilages  behind, 
and  also  ia  the  intervals  between  the  cartilages.    [These  pale  reddish  fibres  con> 


218  STRUCTURE  OF  THE  TRACHEA. 

stitute  the  trachealis  muscle,  and  are  attached  to  the  inner  surfaces  of  the  cartilages 
by  means  of  elastic  tendons  at  a  little  distance  from  their  free-ends  (Munniks,  1697). 
The  arrangement  varies  in  different  animals — thus,  in  the  cat,  dog,  rabbit,  and  rat 
the  miiscular  fibres  are  attached  to  the  external  surfaces  of  the  cartilages,  while  in 
the  pig,  sheep,  and  ox  they  are  attached  to  their  internal  surfaces  (Stirling).] 
Some  muscular  fibres  are  arranged  longitudinally  external  to  the  transverse  fibres 
(Kramer),  The  function  of  these  musciilar  fibres  is  to  prevent  too  great  distension 
when  there  is  great  pressure  within  the  air-passages. 

The  mucous  membrane  consists  of  a  basis  of  very  fine  connective-tissue  con- 
taining much  adenoid-tissue  with  numerous  lymph- corpuscles.  It  also  contains 
numerous  elastic  fibres,  arranged  chiefly  in  a  longitudinal  direction  under  the  base- 
ment membrane.  They  are  also  abundant  in  the  deep  layers  of  the  posterior  part 
of  the  membrane  opposite  the  intervals  between  the  cartilages.  A  small  quantity  of 
loose  sub-mucous  connective-tissue  containing  the  large  blood-A^essels,  glands,  and 
lymphatics  unites  the  mucous  membrane  to  the  perichondrium  of  the  cartilages. 
The  epithelium  consists  of  a  layer  of  columnar  ciliated  cells  with  several  layers  of 
immature  cells  under  them,  [The  superficial  layer  of  ceUs  is  columnar  and 
ciliated  (Fig,  97,  b),  while  those  lying  under  them  present  a  variety  of  forms,  and 
below  all  is  a  layer  of  somewhat  flattened  squames,  c,  resting  on  the  basement 
membrane,  d.  These  squames  constitute  a  layer  quite  distinct  from  the  basement 
membrane,  and  they  form  the  layer  described  by  Deljove.  They  are  active  germi- 
nating cells,  and  play  a  most  important  part  in  connection  with  the  regeneration 
of  the  epithelium,  after  the  superficial  layers  have  been  shed,  in  such  conditions  as 
bronchitis  (v.  Drasch,  Hamilton).  Not  unfrequently  a  little  viscid  mucus  (a)  lies 
on  the  free-ends  of  the  cUia.  In  the  intermediate  layer,  the  ceUs  are  more  or  less 
pyriform  or  battledore-shaped  (Hamilton),  with  their  long  tapering  process  inserted 
amongst  the  deepest  layer  of  squames.  According  to  Drasch,  this  long  process  is 
attached  to  one  of  these  cells  and  is  an  outgrowth  from  it,  the  whole  constituting 
a  "foot-cell."] 

Underneath  the  epithelial  is  the  homogeneous  basement  membrane,  through 
which  fine  canals  pass  connecting  the  cement  of  the  epithelium  with  spaces  iu 
the  mucosa.  [This  membrane  is  well  marked  in  the  human  trachea,  where 
it  plays  an  important  part  in  many  pathological  conditions,  e.g.,  bronchitis. 
It  is  stained  bright  red  with  picrocarmine.]  The  ciha  act  so  as  to  carry 
any  secretion  towards  the  larynx.  Goblet  cells  exist  between  the  ciliated 
columnar  cells.  Numerous  small  compound  tubular  mucous  glands  occur  in 
the  mucous  membrane,  chiefly  between  the  cartilages.  Their  ducts  open  on 
the  surface  by  means  of  a  slightly  funnel-shaped  aperture  into  which  the 
ciliated  epithelium  is  prolonged  for  a  short  distance.  [The  acini  of  some  of  these 
glands  lie  outside  the  trachealis  muscle.  The  acini  are  lined  by  cubical  or 
columnar  secretory  epithelium.  In  some  animals  (dog)  these  cells  are  clear,  and 
present  the  usual  characters  of  a  mucous-secreting  gland  ;  in  man,  some  of  the  cells 
maybe  clear,  and  others  "granular,"  but  the  appearance  of  the  cells  depends 
upon  the  physiological  state  of  activity.]  These  glands  secrete  the  mucus,  which 
entangles  particles  inspired  with  the  air,  and  is  carried  towards  the  larynx  by 
ciliary  action.  [Numerous  lymphatics  exist  in  the  mucous  and  sub-mucous  coat, 
and  not  unfrequently  small  aggregations  of  adenoid  tissue  occur  (especially  in  the 
cat)  in  the  mucous  coat,  usually  around  the  ducts  of  the  glands.  They  are  com- 
parable to  the  solitary  follicles  of  the  alimentary  tract.  The  blood-vessels  are 
not  so  numerous  as  in  some  other  mucous  membranes.  [A  plexus  of  nerves  con- 
taining numerous  ganglionic  cells  at  the  nodes  exists  on  the  posterior  surface  of  the 
trachealis  muscle.  The  fibres  are  derived  from  the  vagus,  recurrent  laryngeal,  and 
sympathetic  (C.  Frankenhauser,  W.  Stirling,  Kandarazi),] 

[The  mucous  membrane  of  the  trachea  and  extra-pulmonary  bronchi, 

therefore,  consists  of  the  following  layers  from  within  outwards  : — 


STRUCTURE  OF  THE  BRONCHI. 


219 


(1.)  Stratified  columnar  ciliated  epithelium. 
(2.)  A  layer  of  flattened  cells  (D^bove's  membrane). 
(3.)  A  clear  homogeneous  basement  membrane. 

(4.)  A  basis  of  areolar  tissue,  with  adenoid  tissue  and  blood-vessels,  and  out- 
side this  a  layer  of  longitudinal  elastic  fibres. 
Outside  this,  again,  is  the  sub-mucous  coat,  consisting  of  loose  areolar  tissue, 
with  the  larger  vessels,  lymphatics,  nerves,  and  mucous  glands.] 

[The  BroncM.— In  structure,  the  extra-pulmonary  bronchi  resemble  the 
trachea.  As  they  pass  into  the  lung  they  divide  dichotomously  very  frequently,  and 
the  branches  do  not  anastomose.   The  subdivisions  become  finer  and  finer,  the  finest 


«sr<2^ 


Fig.  97. 

Transverse  section  of  part  of  a  normal  human  bronchus  (  x  450) — a,  precipitated 
mucus  on  the  surface  of  the  ciliated  epithelium,  b;  b,  ciliated  columnar 
epithelium ;  c,  deep  germinal  layer  of  cells  (D^bove's  membrane) ;  d,  elastic 
basement  membrane ;  e,  elastic  fibres  divided  transversely  (inner  fibrous 
layer);/,  bronchial  muscle  (non-striped);  g,  outer  fibrous  layer  with  leuco- 
cytes and  pigment  granules  (black)  deposited  in  it.  The  lower  part  of  the 
figure  shows  a  mass  of  a  denoid  tissue. 


branches  being  called  terminal  bronchi,  or  bronchioles,  which  open  separately  into 
clusters  of  air- vesicles.] 


220  STRUCTURE   OF   THE   BRONCHI   AND   BRONCHIOLES. 

[In  the  middle-sized  intra-pulmonary  bronchi,  the  usual  characters  of  the 
mucous  membrane  are  retained,  only  it  is  thinner;  the  cartilages  assume  the  form 
of  irregular  plates"  situated  in  the  outer  wall  of  the  bronchus  ;  while  the  muscular 
fibres  are  disposed  in  a  complete  circle  constituting  the  hroncMal  muscle  (Fig. 
97,  /).  When  this  muscle  is  contracted,  'or  when  the  bronchus  as  a  whole  is 
contracted,  the  mucous  membrane  is  thrown  into  longitudinal  folds,  and  opposite 
these  folds  the  elastic  fibres  form  large  elevations.  This  muscle  is  particularly 
well-developed  in  the  smaller  microscopic  bronchi.  Numerous  elastic  fibres,  e, 
disposed  longitudinally,  exist  under  the  basement  membrane,  d.  They  are  con- 
tinuous with  those  of  the  trachea,  and  are  continued  onwards  into  the  lung. 
The  mucous  membrane  of  the  larger  intra-pulmo7iary  bronchi  consists  of  the 
following  layers  from  within  outwards : — 

(1.)  Stratified  columnar  ciliated  epithelium  (Fig.  97,  b). 
(2. )  D^bove's  membrane  (Fig.  97,  c). 

(3.)  Transparent  homogeneous  basement  membrane  (Fig.  97,  (I). 
(4.)  Areolar  tissue  with  longitudinal  elastic  fibres  (Fig.  97,  e). 
(5.)  A  continuous   layer  of  non-striped   muscular  fibres  disposed  circularly 
{bronchial  muscle — Fig.  97,/). 

Outside  this  is  the  sub-mucous  coat,  consisting  of  areolar  tissue  mixed  with  much 
adenoid  tissue  (Fig.  97,  g),  sometimes  arranged  in  the  form  of  cords,  the  lymph- 
follicular  cords  of  Klein.  It  also  contains  the  acini  of  the  numerous  mucous  glands, 
blood-vessels,  and  lymphatics.  The  ducts  of  the  glands  perforate  the  muscular 
layer,  and  open  on  the  free  surface  of  the  mucous  membrane.  The  sub-mucous 
coat  is  connected  by  areolar  tissue  with  the  perichondrium  of  the  cartilages. 
Outside  the  cartilages  are  the  nerves  and  nerve  ganglia  accompanying  the  bronchial 
vessels.  A  branch  of  the  pulmonary  artery  and  pulmonary  vein  usually  lie  on 
opposite  sides  of  the  bronchus,  while  there  are  several  branches  of  the  bronchial 
arteries  and  veins.     Fat  cells  also  occur  in  the  peri-bronchial  tissue.] 

In  the  small  broncM  the  cartilages  and  glands  disappear,  but  the  circular 
muscular  fibres  are  well  developed.  They  are  lined  by  lower  columnar  ciliated 
epithelium,  containing  goblet  cells. 

Bronchioles. — After  repeated  subdivision,  the  bronchi  form  the  '■^smallest 
bronchi"  (about  0*5-1  mm.)  or  lobular  bronchial  tubes.  Each  tube  is  lined  by  a 
layer  of  ciliated  epithelium,  but  the  glands  and  cartilages  have  disappeared. 
These  tubes  have  a  few  lateral  alveoli  or  air-cells  communicating  with  them.  Each 
smallest  bronchus  ends  in  a  "  respiratory  bronchiole"  (KoUiker),  which  gradually 
becomes  beset  with  more  air-cells,  and  in  which  squamous  epithelium  begins 
to  appear  between  the  ciliated  epithelial  cells.  [Each  bronchiole  opens  into  several 
wider  alveolar  or  lobular  passages.  Each  passage  is  completely  surrounded  with 
air-cells,  and  from  it  are  given  off  several  similar  but  wider  blind  branches,  the 
infundibula,  which,  in  their  turn,  are  beset  on  all  sides  with  alveoli  or  air-cells. 
Several  infundibula  are  connected  with  each  bronchiole,  and  the  former  are  wider 
than  the  latter.  Each  bronchiole,  with  its  alveolar  passages,  infundibula,  and  air- 
vesicles,  is  termed  a  lobule,  whose  base  is  directed  outwards,  and  whose  apex  may 
be  regarded  as  a  terminal  bronchus.  The  lung  is  made  up  of  an  immense  number 
of  these  lobules,  separated  from  each  other  by  septa  of  connective-tissue,  the  inter- 
lobular septa  (Fig.  100,  e)  which  are  continuous  on  the  one  hand  with  the  sub-pleural 
connective- tissue,  and  on  the  other  with  the  peri-bronchial  connective-tissue.  ] 

[It  is  evident  that  there  is  an  alteration  in  the  structure  of  the  bronchi,  as  we 
proceed  from  the  larger  to  the  smaller  tubes.  The  cartilages  and  glands  are  the 
first  structures  to  disappear.  The  circular  bronchial  muscle  is  well  developed  in 
the  smaller  bronchi,  and  bronchioles,  and  exists  as  a  continuous  thin  layer  over 
the  alveolar  passages,  but  it  is  not  continued  over  and  between  the  air-cells. 
Elastic  fibres,  continuous,  on  the  one  hand,  with  those  in  the  smaller  bronchi,  and 


STRUCttTRE   01*  THE  AIR-CELLS. 


221 


on  the  other,  with  those  in  the  walls  of  the  air-cells,  lie  outside  the  muscular 
fibres  in  the  bronchioles  and  infundibula.  In  the  respiratory  bronchioles,  the 
ciliated  epithelium  is  reduced  to  a  single  layer,  and  is  mixed  with  the  stratified 
form  of  epithelium,  while,  where  the  alveolar  passages  open  into  the  air-cells  or 
alveoli,  the  epithelium  is  non-ciliated,  low,  and  polyhedral.] 

Alveoli  or  Air-Cells.— The  form  of  the  air-cells,    which  are  250m  [tU  inch) 
in  diameter,  may  be  more  or  less  spherical,  polygonal,  or  cup-shaped.     They  are 
disposed  around  and  in  communication  with  the  alveolar  passages.     Their  form 
is  determined  by  the  existence  of  a  nearly  structureless  membrane,  composed  of 
slightly  fibrillated  connective-tissue  containing  a   few  corpuscles.     This  is  sur- 
rounded by  numerous  fine  elastic  fibres  which  give  to  the  pulmonary  parenchyma 
its  well-marked  elastic  characters  (Fig.  99,   e,  e).     These  fibres  often  bifurcate, 
and  are   arranged  with  reference  to  the   alveolar  wall.     They  are  very  resist- 
ant,   and   in    some    cases    of   lung-disease  may   be  recognised   in  the    sputum. 
A    few    non-striped     mus- 
cular   fibres    exist    in    the 
delicate    connective  -  tissue 
between  adjoining    air-ves- 
icles   (Moleschott).      These 
muscular    fibres    sometimes 
become  greatly  developed  in 
certain    diseases    (W.    Stir- 
ling).   The  air-cells  are  lined 
by  two  kinds   of  cells— (1) 
large,  transparent,  clear  poly - 
gonal  (nucleated?)  squames 
or  placoids   (22-45iu)    lying 
over  and  between  the  capil- 
laries in  the  alveolar  wall 
(Fig.  98,  a);  (2)  small  irre- 
gular '■^granular"  nucleated 
cells  (7-15/a)  arranged  singly 
or  in  groups  (two  or  three) 
in  the  interstices   between 
the  capillaries.      They  are 
well    seen  in  a  cat's  lung 
(Fig.  98,  d).     [When  acted 
on  with  nitrate  of  silver  the 
cement-substance  bounding 
the  clear  cells    is    stained, 
but  the  small  cells  become  of 
a  uniform  brown    granular 
appearance,  so  that  they  are 
readily  recognised.      Small 
holes  or   " pseudo-stomata  " 
seem  to  exist  in  the  cement-substance,   and  are  most  obvious  in  distended  alveoli 
(Klein).     They  open  into  the  lymph-canalicular  system  of  the  alveolar  wall  (Klein), 
and  through  them  the  lymph-corpuscles,  which  are  always  to  be  found  on  the 
surface  of  the  air- vesicles,  migrate,  and  carry  with  them  into  the  lymphatics  par- 
ticles of  carbon  derived  from  the  air.  ]   In  the  alveolar  walls  is  a  very  dense  plexus  of 
fine  capillaries  (Fig.  99,  c),  which  lie  more  towards  the  cavity  of  the  air-vesicle 
(Rainey),  being  covered  only  by  the  epithelial  lining  of  the  air-cells.    Between  two 
adjacent  alveoli  there  is  only  a  single  layer  of  capillaries  (man),    and  on  the 
boundary  line  between  two  air-cells  the  course  of  the  capillaries  is  twisted,  thus 
projecting  sometimes  into  the  one  alveolus,  sometimes  into  the  other. 


Fig.  98. 

Air- vesicles  from  a  kitten  whose  lungs  were  injected 
with  silver  nitrate  (  x  450)— a,  outlines  of  fully- 
developed  squamous  epithelium;  6,  alveolar  wall; 
c,  young  epithelial  cell  losing  its  granular  appear- 
ance; d,  aggregation  of  young  epithelial  cells 
germinating. 


222 


THE  BLOOD-VESSELS   OF  THE  LUNG. 


The  Blood-vessels  of  the  lung  belong  to  two  diflferent  systems : — (A)  Pul- 
monary VESSELS  (lesser  circulation).  The  branches  of  the  pulmonary  artery 
accompany  the  bronchi  and  are  closely  applied  to  them.  [As  they  proceed  they 
branch,  but  the  branches  do  not  anastomose,  and  ultimately  they  terminate  in 
small  arterioles  which  supply  several  adjacent  alveoli,  each  arteriole  splitting  up  into 
capillaries  for  several  air-cells  (Fig.  99,  v,  c).  An  efferent  vein  usually  arises  at  the 
opposite  side  of  the  air-cells  and  carries  away  the  purified  blood  from  the  capillaries. 
In  their  course  these  veins  unite  to  form  the  pulmonary  veins  which  are  joined  in 
their  course  by  a  few  small  bronchial  veins  (Zuckerkandl).  The  veins  usually 
anastomose  in  the  earlier  part  of  their  course,  whilst  the  corresponding  arteries  do 
not.]  Although  the  capOlary  plexus  is  very  fine  and  dense,  its  sectional  area 
is  less  than  the  sectional  area  of  the  systemic  capillaries,  so  that  the  blood-stream 
in  the  pulmonary  capillaries  must  be  more  rapid  than  that  in  the  capillaries  of  the 
body  generally.     The  pulmonary  veins,  unlike  veins  generally,   are  collectively 


Fig.  99. 

Semi-schematic  representation  of  the  air  vesicles  of  the  lung—?;,  v,  blood-vessels 
at  the  margins  of  an  alveolus  ;  c,  c,  its  blood  capillaries  ;  E,  relation  of  the 
squamous  epithelium  of  an  alveolus  to  the  capillaries  in  its  wall ;  /,  alveolar 
epithelium  shown  alone  ;  e,  e,  elastic  tissue  of  the  lung. 

narrower  than  the  pulmonary  artery  (water  is  given  off  in  the  limg),  and  they  have 
no  valves.  [The  pulmonary  artery  contains  venous  blood,  and  the  pulmonary  veins 
pure  or  arterial  blood], 

(B)  The  BRONCHIAL  VESSELS  represent  the  nutrient  system  of  the  lungs.  They 
(1-3)  arise  from  the  aorta  (or  intercostal  arteries)  and  accompany  the  bronchi 
without  anastomosing  with  the  branches  of  the  pulmonary  artery.  In  their 
course    they  give  branches  to  the  lymphatic  glands  at  the  hilum  of  the  lung, 


THE   PLEURA  AND   THE   LYMPHATICS   OF  THE   LUNG. 


223 


to  the  walls  of  the  large  blood-vessels  (vasa  vasorum),  the  pulmonary  pleura, 
the  bronchial  walls,  and  the  interlobular  septa.  The  blood  which  issues  from 
their  capillaries  is  returned — partly  by  the  pulmonary  veins — hence,  any  con- 
siderable interference  mth  the  pulmonary  circulation  causes  congestion  of  the 
bronchial  mucous  membrane,  resulting  in  a  catarrhal  condition  of  that  membrane. 
The  greater  part  of  the  blood  is  returned  by  the  bronchial  veins  which  open  into 
the  vena  azygos,  intercostal  vein,  or  superior  vena  cava.  The  veins  of  the  smaller 
bronchi  (fourth  order  onwards)  open  into  the  pulmonary  veins,  and  the  anterior 
bronchial  also  communicate  with  the  pulmouary  veins  (Zuckerkandl). 

[The  Pleura. — Each  pleural  cavity  is  distmct,  and  is  a  large  serous  sac,  which 
really  belongs  to  the  lymphatic  system  of  the  lung.  The  pleura  consists  of  two 
layers,  visceral  and  j^ciri- 
etal.  The  visceral  j)leura 
covers  the  lung ;  the  pari- 
etal portion  lines  the 
wall  of  the  chest,  and  the 
two  layers  of  the  corre- 
sponding pleura  are  con- 
tinuous with  one  another 
at  the  root  of  the  lung. 
The  visceral  pleura  is  the 
thicker,  and  may  readily 
be  separated  from  the 
inner  surface  of  the  chest. 
Structurally,  the  pleura 
resembles  a  serous  mem- 
brane, and  consists  of  a 
thin  layer  of  fibrous  tissue 
covered  by  a  layer  of  en- 
dothelium. Under  this 
layer,  or  the  pleura  pro- 
per, is  a  deep  or  sub-serous 
layer  of  looser  areolar 
tissue,  containmg  many 
elastic  fibres.  This  layer 
of  the  pleura  pulmonalis 
of  some  animals,  as  the 
gumea  -  pig,  contains  a 
net-work  of  non- striped 
muscular  fibres  (Klein). 
Over  the  lung  it  is  also 
continuous  with  the  in- 
terlobular septa.  The 
interlobular  septa  (Fig. 
100,  e)  consist  of  bands 
of  fibrous  tissue  separat- 
ing adjoining  lobules,  and 
they  become  contmuous  with  the  peri-bi'onchial  connective-tissue  entering  the 
lung  at  its  hilum.  Thus  the  fibrous  framework  of  the  lung  is  continuous  through- 
out the  lung,  just  as  in  other  organs.  The  connection  of  the  sub-pleural  fibrous 
tissue  with  the  comaective-tissue  within  the  substance  of  the  lung,  has  most  im- 
portant pathological  bearings.  The  interlobular  septa  contain  lymphatics  and 
blood-vessels.  The  endothelium  covermg  the  parietal  layer  is  of  the  ordinai-y 
squamous  type,  but  on  the  pleura  pulmonalis  the  cells  are  less  flattened,  more 
polyhedral,  and  granular.     They  must  necessarily  vary  in  shape  with  changes  ui 


Normal  human  lung  (xoO  and  reduced  |) — a,  small 
bronchus;  bb,  branches  of  the  puhnonary  artery; 
c,  branch  of  the  pulmonary  vein;  e,  interlobular 
septa,  continuous  with  the  deep  layer  of  the 
pleura,  p. 


224  THE  LYIMPHATICS  OF  THE  LUNG. 

the  volume  of  the  lung,  so  that  they  ai-e  more  flattened  when  the  lung  is  distended, 
as  during  inspiration  (Klein).  The  pleura  contains  many  lymphatics,  which  com- 
municate by  means  of  stomata  with  the  pleural  cavity.] 

[The  Lymphatics  of  the  lung  are  numerous  and  are  arranged  in  several 
systems.  The  various  air-cells  are  connected  with  each  other  by  very  delicate 
connective-tissue,  and  according  to  J.  Arnold  in  some  parts  this  interstitial  tissue 
presents  characters  like  those  of  adenoid  tissue ;  so  that  the  lung  is  traversed  by  a 
system  of  juice-canals  or  Saft-canalchen.]  [In  the  deep  layer  of  the  pleura,  there  is 
a  (o)  suh-pleural  plexus  of  lymphatics  partly  derived  from  the  pleura,  but  chiefly 
from  the  lymph-canalicular  system  of  the  pleural  alveoli.  Some  of  these  branches 
proceed  to  the  bronchial  glands,  but  others  pass  into  the  interlobular  septa,  where 
they  join  (&)  the  peri-vascular  lymphatics  which  arise  in  the  lymph-canalicular 
system  of  the  alveoli.  These  trunks,  provided  with  valves,  run  alongside  the 
pulmonary  artery  and  vein,  and  in  their  course  they  form  frequent  anastomoses. 
Special  vessels  arise  within  the  walls  of  the  bronchi  and  occur  chiefly  in  the 
outer  coat  of  the  latter,  constituting  (c)  the  peri-hronchial  lymphatics,  which 
anastomose  with  h.  The  branches  of  these  two  sets  run  towards  the  bronchial 
glands.  Not  unfrequently  (cat)  masses  of  adenoid  tissue  are  found  in  the  course 
of  these  lymphatics  (Klein)].  The  lymph-canalicular  system  and  the  lymphatics 
become  injected  when  fine  coloured  particles  are  inspired,  or  are  introduced  into 
the  air-cells  artificially.  The  pigment  particles  pass  through  the  semi-fluid  cement 
substance  into  the  lymjjh-canalicular  system  and  thence  into  the  lymphatics 
(v.  Wittich)  ;  or,  according  to  Klein,  they  pass  through  actual  holes  or  pores  in  the 
cement  (p.  221).  [This  pigmentation  is  well  seen  in  coal-miners'  lung  or  anthra- 
cosis,  where  the  particles  of  carbon  pass  into  and  are  found  in  the  lymphatics. 
Sikorski  and  Kuttner  showed  that  pigment  reached  the  lymphatics  in  this  way 
during  life.  If  pigment,  China  ink,  or  indigo  carmine  be  introduced  into  a  frog's 
lung,  it  is  found  in  the  lymphatic  system  of  the  lung.  Euppert,  and  also 
Schottelius,  showed  that  the  same  result  occurred  in  dogs  after  the  inhalation  of 
charcoal,  cinnabar,  or  precipitated  Berlin  blue,  and  von  Ins  after  the  inhalation  of 
silica.  A.  Schestopal  used  China  ink  and  cinnabar  suspended  in  f  p.c.  salt 
solution.] 

Excessively  fine  lymph-canals  lie  in  the  wall  of  the  alveoli  in  the  interspaces  of 
the  capillaries,  and  there  are  slight  dilatations  at  the  points  of  crossing 
(Wydwozoff).  According  to  Pierret  and  Renaut  every  air-ceU  of  the  lung  of  the 
ox  is  surrounded  by  a  large  lymph-space,  such  as  occurs  in  the  salivary  glands. 
When  a  large  quantity  of  fluid  is  injected  into  the  lung  it  is  absorbed  with  great 
rapidity,  even  blood-corpuscles  rapidly  pass  into  the  lymphatics.  [Nothnagel 
found  that,  if  blood  was  sucked  into  the  lung  of  a  rabbit,  the  blood-corpuscles  were 
found  within  the  interstitial  connective-tissue  of  the  lung  after  3^-5  minutes, 
from  which  he  concludes  that  the  communications  between  the  cavity  of  the  air- 
cells  and  the  lymphatics  must  be  very  numerous.] 

The  superficial  lymphatics  of  the  pulmonary  pleura  communicate  with  the 
pleural  cavity  by  means  of  free  openings  or  stomata  (Klein),  and  the  same  is  true 
of  the  lymphatics  of  the  parietal  pleura,  but  these  stomata  are  confined  to  limited 
areas  over  the  diaphragmatic  pleura.  [The  Ijrmphatics  in  the  costal  pleura  occur 
over  the  intercostal  spaces  and  not  over  the  ribs  (Dybkowski).]  The  large  arteries 
of  the  lung  are  provided  with  lymphatics  which  lie  between  the  middle  and  outer 
coats  (Grancher). 

[The  movements  of  the  lung  during  respiration  are  most  important  factors  in 
moving  the  lymph  onwards  in  the  pulmonary  lymphatics.  The  return  of  the 
lymph  is  prevented  by  the  presence  of  valves,] 

[The  Nerves  of  the  lung  are  derived  from  the  anterior  and  posterior  pulmonary 
plexuses,  and  consist  of  branches  from  the  vagus  and  sympathetic.  They  enter 
the  lungs  and  follow  the  distribution  of  the  bronchi,  several  sections  of  nerve- 


PHYSICAL  PROPERTIES  OF  THE  LUNGS.  225 

trunks  being  usually  found  in  a  section  of  a  large  bronchial  tube.  These  nerves 
lie  outside  the  cartilages,  and  are  in  close  relation  with  the  branches  of  the 
bronchial  arteries.  MeduUated  and  non-medullated  nerve-fibres  occur  in  the 
ner%-es,  which  also  contain  numerous  small  r/miglia  (Reniak,  Klein,  Stirling).  In 
the  limg  of  the  calf  these  ganglia  are  so  large  as  to  be  macroscopic.  The  exact 
mode  of  termination  of  the  nerve-fibres  within  the  lung  has  yet  to  be  ascertained 
in  mammals,  but  some  fibres  pass  to  the  bronchial  muscle,  others  to  the  large 
blood-vessels  of  the  lung,  and  it  is  highly  probable  that  the  mucous  glands  are  also 
supplied  \vith  nerve  filaments.  In  the  comparatively  simple  lungs  of  the  frog, 
nerves  ^^■ith  numerous  nerve-cells  in  their  course  are  found  (Arnold,  Stirling),  and 
in  the  very  simple  lung  of  the  newt,  there  are  also  numerous  nerve-cells  disposed 
along  the  course  of  the  intra-pulmonary  nerves.  Some  of  these  fibres  terminate  in 
the  uniform  layer  of  non-striped  muscle  which  forms  part  of  the  pulmonaiy  wall 
in  the  frog  and  newt,  and  others  end  in  the  muscular  coat  of  the  pulmonary 
blood-vessels  (vStirling).  The  functions  of  these  ganglia  are  unkno'wn,  but  they 
may  be  compared  to  the  nerve-plexuses  existing  in  the  walls  of  the  digestive 
tract.  ] 

The  Function  of  the  Non-striped  Muscle  of  the  entire  bronchial 
system  seems  to  be  to  oflfer  a  sufficient  amount  of  resistance  to  increased 
pressure  within  the  air-passages;  as  in  forced  expiration,  speaking, 
singing,  blowing,  etc.  The  vagus  is  the  motor-nerve  for  these  fibres, 
and  according  to  Longet  (1842),  the  "lung-tonus"  during  increased 
tension  depends  upon  these  muscles.  Stimulation  of  the  lower  end  of 
the  vagus  causes  a  slight  contraction  of  the  bronchial  muscles,  but  the 
movement  is  neither  sudden  nor  considerable.  It  is  highly  doubtful  if 
bronchial  (spasmodic)  asthma  depends  upon  contraction  of  these  mus- 
cular fibres  due  to  stimulation  of  the  vagus. 

Chemistry. — In  addition  to  connective,  elastic,  and  muscular  tissue,  the  lungs 
contain  lecithin,  inosit,  uric  acid  (tam-in  and  leucin  in  the  ox),  guanin,  xanthin  (?), 
hypoxanthin  (dog) — soda,  potash,  magnesium,  oxide  of  iron,  much  phosphoric 
acid,  also  chlorine,  sulphuric  and  silicic  acids — in  diabetes  sugar  occurs — in 
purulent  infiltration  glycogen  and  sugar — in  renal  degeneration  urea,  oxalic  acid, 
and  ammonia  salts ;  and  in  diseases  where  decomposition  takes  place,  leucin  and 
tyrosin. 

[Physical  Properties  of  the  Lungs. — The  lungs,  in  virtue  of  the  large 
amount  of  elastic  tissue  which  they  contain,  are  endowed  with  great  elas- 
ticity,  so  that  when  the  chest  is  opened,  they  collapse.  If  a  cannula  with 
a  small  lateral  opening  be  tied  into  the  trachea  of  a  rabbit's  or  sheep's 
lungs,  the  lungs  may  be  inflated  with  a  pair  of  bellows,  or  elastic  pump. 
After  the  artificial  inflation,  the  lungs,  owing  to  their  elasticity,  collapse 
and  expel  the  greater  part  of  the  air.  As  much  air  remains  within 
the  light  spongy  tissue  of  the  lungs,  even  after  they  are  removed  from 
the  body,  a  healthy  lung  floats  in  water.  If  the  air-cells  are  filled 
with  pathological  fluids  or  blood,  as  in  certain  diseased  conditions  of 
the  lung  (pneumonia),  then  the  lungs  or  parts  thereof  may  sink  in 
water.  The  lungs  of  the  foetus,  before  respiration  has  taken  place, 
sink  in  water,  but  after  respiration  has  been  thoroughly  established  in 

15 


226  MECHANISM   OF   RESPIRATION. 

the  child,  the  lungs  float.  Hence,  this  hydrostatic  test  is  largely  used  in 
medico-legal  cases,  as  a  test  of  the  child  having  breathed.  If  a  healthy 
lung  be  squeezed  between  the  fingers,  it  emits  a  peculiar  and  character- 
istic fine  crackling  sound,  owing  to  the  air  within  the  air-cells.  A 
similar  sound  is  heard  on  cutting  the  vesicular  tissue  of  the  lung.  The 
colour  of  the  lungs  varies  much ;  in  a  young  child  it  is  rose-pink,  but 
afterwards  it  becomes  darker,  especially  in  persons  living  in  towns  or 
a  smoky  atmosphere,  owing  to  the  deposition  of  granules  of  carbon. 
In  coal-miners  the  lungs  may  become  quite  black.] 


107.  Mechanism  of  Respiration. 

The  mechanism  of  respiration  consists  in  an  alternate  dilatation  and 
contraction  of  the  chest.  The  dilatation  is  called  inspiration,  the  con- 
traction expiration.  As  the  whole  external  surfaces  of  both  elastic  lungs 
are  applied  directly,  and  in  an  air-tight  manner  by  their  smooth  moist 
pleural  investment  to  the  inner  wall  of  the  chest,  which  is  covered  by 
the  parietal  pleura,  it  is  clear,  that  the  lungs  must  be  distended  with 
every  dilatation  of  the  chest,  and  diminished  by  every  contraction 
thereof.  These  movements  of  the  lungs,  therefore,  are  entirely  passive, 
and  are  dependent  on  the  thoracic  movements  (Galen). 

On  account  of  their  complete  elasticity  and  their  great  extensibility, 
the  lungs  are  able  to  accommodate  themselves  to  any  variation  in  the  size 
of  the  thoracic  ca\ity,  without  the  two  layers  of  the  pleura  becoming 
separated  from  each  other.  As  the  capacity  of  the  non-distended  chest 
is  greater  than  the  volume  of  the  collapsed  lungs  after  their  removal 
from  the  body,  it  is  clear  that  the  lungs  even  in  their  natural  position 
within  the  chest  are  distended,  i.e.,  they  are  in  a  certain  state  of 
ELASTIC  TENSION  (§  60).  The  tension  is  greater  the  more  distended 
the  thoracic  cavity,  and  vice  versa.  As  soon  as  the  pleural  cavity  is 
opened  by  perforation  from  without,  the  lungs,  in  virtue  of  their 
elasticity,  collapse,  and  a  space  filled  with  air  is  formed  between  the 
surface  of  the  lungs  and  the  inner  surface  of  the  thoracic  wall  (pneumo- 
thorax). The  lungs  so  affected  are  rendered  useless  for  respiration; 
hence  a  double  pneumo-thorax  causes  death. 

It  is  also  clear  that,  if  the  pulmonary  pleura  be  perforated  from  within  the  lung, 
air  will  pass  from  the  respiratory  passages  into  the  pleux'al  sac,  and  also  give  rise 
to  pneumo-thorax. 

[Not  unfrequently  the  surgeon  is  called  on  to  open  the  chest,  say  by  removing  a 
portion  of  a  rib  to  allow  of  the  free  exit  of  pus  from  the  pleural  cavity.  If  this 
be  done  with  proper  precautions,  and  if  the  external  wound  be  allowed  to  heal, 
after  a  time  the  air  in  the  pleural  cavity  becomes  absorbed,  the  collapsed  lung 
tends  to  regain  its  original  form,  and  again  becomes  functionally  active.] 


QUANTITY   OF  GASES  RESPIRED. 


227 


Estimation  of  Elastic  Tension. — If  a  manometer  be  introduced  through  an 
intercostal  space  into  the  pleural  cavity,  in  a  dead  subject,  we  can  measure,  by 
means  of  a  column  of  mercury,  the  amount  of  the  elastic  tension  required  to  keep 
the  lung  in  its  position.  This  is  equal  to  6  mm.  in  the  dead  subject,  as  well  as  in 
the  condition  of  expiration.  If,  however,  the  thorax  be  brought  into  the  position 
of  inspiration  by  the  application  of  traction  from  without,  the  elastic  tension  may 
be  increased  to  30  mm.  Hg.  (Bonders). 

If  the  glottis  be  closed  and  a  deep  inspiration  taken,  the  air  within 
the  lungs  must  become  rarified,  because  it  has  to  fill  a  greater 
space.  If  the  glottis  be  suddenly  opened,  the  atmospheric  air  passes 
into  the  lungs  until  the  air  within  the  lungs  has  the  same  density  as 
the  atmosphere.  Conversely,  if  the  glottis  be  closed,  and  if  an  expira- 
tory effort  be  made,  the  air  within  the  chest  must  be  compressed.  If 
the  glottis  be  suddenly  opened,  air  passes  out  of  the  lungs  until  the 
pressure  outside  and  inside  the  lung  is  equal.  As  the  glottis  remains 
open  during  ordinary  respiration,  the  equilibration  of  the  pressure 
within  and  without  the  lungs  will  take  place  gradually.  During 
tranquil  inspiration  there  is  a  slight  negative  pressure ;  during  expira- 
tion a  slight  positive  pressure  in  the  lungs ;  the  former  =  1  mm., 
the  latter,  2  —  3  mm.  Hg.  in  the  human  trachea  (measured  in  cases  of 
wounds  of  the  trachea). 


108.  Quantity  of  Gases  Respired. 

As  the  lungs  within  the  chest  never  give  out  aU  the  air  they  contain, 
it  is  clear,  that  only  a  part  of  the  air  of  the  lungs  is  changed  during  in- 
spiration and  expiration.  The  volume  of  this  air  will  depend  upon  the 
depth  of  the  respirations. 

Hutchinson   (1846)   distinguishes  the    following 
points : — 


COMPLEMENTAL 
AIR, 

110 


TIDAL  AIR, 
20 


RESERVE   AIR, 
100 


RESIDUAL  AIR, 

100 


o   ta 


(1.)  Residual  Air  is  the  volume  of  air  which 
remains  in  the  chest  after  the  most  complete  expira- 
tion. It  is  equal  to  1,230-1,640  c.c.  [100-130  cubic 
inches.] 

(2. )  Reserve  or  Supplemental  Air  is  the  volume 

of  air  which  can  be  expelled  from  the  chest  after  a 
normal  quiet  expiration.  It  is  equal  to  1,240-1,800 
c.c.  [100  cubic  inches.] 

(3.)  Tidal  Air  is  the  volume  of  air  which  is 
taken  in  and  given  out  at  each  respiration.  It  is 
equal  to  500  cubic  centimetres  [20  cubic  inches.] 

(4.)  Complemental  Air  is  the  volume  of  air 
that  can  be  forcibly  inspired  over  and  above  what 
is  taken  in  at  a  normal  respiration.  It  amounts  to 
about  1,500  c.c.  [100-130  cubic  inches.] 


228 


SPIROMETRY  AND  VITAL  CAPACITY. 


(5.)  Vital  Capacity  is  the  term  applied  to  the  volume  of  air  which 
can  be  forcibly  expelled  from  the  chest  after  the  deepest  possible 
inspiration.  It  is  equal  to  3,772  c.c.  (or  230  cubic  inches)  for  an 
Englishman  (Hutchinson),  and  3,222  for  a  German  (Haeser). 

Hence,  after  every  quiet  inspiration,  both  lungs  contain  (1  +  2  +  3) 
=r  3,000-3,900  c.ctmr.  [220  cubic  inches] ;  after  a  quiet  expiration 
n +2)  =  2,500-3,400  c.ctmr.  [200  cubic  inches.]  So  that  about  ^ 
to  i  of  the  air  in  the  lungs  is  subject  to  renewal  at  each  respiration. 

Estimation  of  Vital  Capacity. — The  estimation  of  the  vital  capacity 
was  formerly  thought  to  be  of  great  consequence,  but  at  the  present  time 
not  much  importance  is  attached  to  it,  nor  is  it  frequently  measured  in 
cases  of  disease.      It  is  estimated  by  means  of  the  spirometer  of 

Hutchinson,  This  instrument  (Fig. 
101),  consists  of  a  graduated 
cylinder  filled  with  water  and  in- 
verted like  a  gasometer  over  water, 
and  balanced  by  means  of  a  counter- 
poise. Into  this  cylinder  a  tube 
projects,  and  this  tube  is  connected 
with  a  mouth-piece.  The  person 
to  be  experimented  upon  takes  the 
deepest  possible  inspiration,  closes 
his  nostrils,  and  breathes  forcibly 
into  the  mouth-piece  of  the  tube. 
After  doing  so  the  tube  is  closed. 
The  cylinder  is  raised  by  the  air 
forced  into  it,  and  after  the  water 
inside  and  outside  the  cylinder  is 
equalised,  the  height  to  which  the 
cylinder  is  raised  indicates  the 
amount    of  air  expired,  or  the  vital 


V^ 


Fig.  101. 
Scheme  of  Hutchinson's  Spirometer. 
or  respiratory  capacity.     In  a  man  of  average  height,  5  feet  8  inches, 
it  is  equal  to  230  cubic  inches. 

The  following  circumstances  affect  the  vital  capacity : — 

(1.)  The  height. — Every  inch  added  to  the  height  of  persons  between  5  and  6 
feet,  gives  an  increase  of  the  vital  capacity =130  c.c.  [8  cubic  inches.] 

(2.)  The  body- weight. — When  the  body- weight  exceeds  the  normal  by  7  per 
cent.,  there  is  a  diminution  of  37  c.c.  of  the  vital  capacity  for  every  kilo,  of  increase. 

(3.)  Age. — The  vital  capacity  is  at  its  maximum  at  35  ;  there  is  an  annual 
decrease  of  23'4  c.  c.  from  this  age  onwards  to  65,  and  backwards  to  15  years  of  age. 

(4. )  Sex- — It  is  less  in  women  than  men,  and  even  where  there  is  the  same  cir- 
cumference of  chest,  and  the  same  height  in  a  man  and  a  woman,  the  ratio  is  10  :  7. 

(5.)  Position- — More  air  is  respired  in  the  erect  than  in  the  recumbent  position. 

(6.)  Disease. — Abdominal  and  thoracic  diseases  diminish  it. 


NmrBER   OF  RESPIRATIONS.  229 

109.  Number  of  Respirations. 

In  the  adult,  the  number  of  respirations  varies  from  16  to  24  per 
minute,  so  that  about  4  pulse-beats  occur  during  each  respiration. 
The  number  of  respirations  is  influenced  by  many  conditions  : — 

(1.)  The  position  of  the  body.— In  the  adult,  in  the  horizontal  positioD,  Guy 
counted  13,  while  sitting  19,  while  standing  22,  respirations  per  minute. 

(2.)  The  age.— Quetelet  found  the  mean  number  of  respirations  in  300 
individuals  to  be  : — 


Year. 

Eespirations. 

) 

0-1, 

44 

1 

5, 

26 

1         Average  Number 

15-20, 

20 

/                      per 

20-25, 

18-7 

1                   Minute. 

25-30, 

16 

\ 

30-50, 

18-1 

J 

(3.)  The  state  of  activity. — Gorham  counted  in  children  of  2  to  4  years  of  age, 
during  standing  32,  in  sleep  24,  respirations  per  minute.  During  bodily  exertion 
the  number  of  respirations  increases  before  the  heart-beats.  [Very  alight  muscular 
exertion  suffices  to  increase  the  frequency  of  the  respirations.] 

[(4.)  The  temperature  of  the  surrounding  medium. — The  respirations  become 
more  numerous  the  higher  the  surrounding  temperature,  but  this  result  only 
occurs  when  the  actual  temperature  of  the  blood  is  increased,  as  in  fever. 

(5.)  Digestion- — There  is  a  slight  variation  during  the  course  of  the  day,  the 
increase  being  most  marked  after  mid-day  dinner  (Vierordt). 

(6.)  The  will  can  to  a  certain  extent  modify  the  number  and  also  the  depth  of 
the  respirations,  but  after  a  short  time  the  impulse  to  respire  overcomes  the 
voluntary  impulse. 

(7.)  The  gases  of  the  blood  have  a  marked  efifect,  and  so  has  the  heat  of  the 
blood  iu  fever.] 


110.  Time  occupied  by  the  Respiratory  Movements. 

The  time  occupied  in  the  various  phases  of  a  respiration  can  only  be 
accurately  ascertained  by  obtaining  a  curve  or  pneumatogram  of  the 
respiratory  movements. 

Methods. — Vierordt  and  C,  Ludwig  transferred  the  movements  of  a  part  of  the 
chest-wall  to  a  lever  which  inscribed  its  movements  upon  a  revolving  cylinder. 
Eiegel  (1873)  constructed  a  "double  stethograph"'  on  the  same  principle.  This 
instrument  is  so  arranged  that  one  arm  of  the  lever  may  be  applied  in  connection 
with  the  healthy  side  of  a  person's  chest,  and  the  other  on  the  unsound  side. 

(2.)  An  air-tambour,  such  as  is  used  in  Brondgeesfs  pansphygmograjjh  (Fig.  103, 
A)  may  be  used.  It  consists  of  a  brass  vessel,  a,  shaped  like  a  small  saucer.  The 
mouth  of  the  brass  vessel  is  covered  with  a  double  layer  of  caoutchouc  membrane, 
b,  c,  and  air  is  forced  in  between  the  two  layers  until  the  external  membrane 
bulges  outwards.  This  is  placed  on  the  chest,  and  the  apparatus  is  fixed  in  posi- 
tion by  means  of  the  bands,  d,  d.  The  cavity  of  the  tambour  communicates  by 
means   of  a  caoutchouc   tube,    >■,  with  a  recording  tambour  which  inscribes  its 


230 


VAKIOUS  POUMS  OP  STETHOGEAPHS. 


Fig.  102. 
Marey's  Stethograph, 


A 


B 

Pig.  103. 

A,  Brondgeest's  tambour  for  registering  the  respiratory  movements— 6,  c,  inner 
and  outer  caoutcliouc  membranes;  a,  the  capsule;  d,  d,  cords  for  fastening 
the  instrument  to  the  chest;  S,  tube  to  the  recording  tambour;  B,  normal 
respiratory  curve  obtained  on  a  vibrating  plate  (each  vibration  =  0  01613  sec). 


IVIEASUREMENT  OP  THE  TIME  OF  THE  RESPIRATORY  MOVEMENTS.    231 

movements  upon  a  revolving  cylinder.  Every  dilatation  of  the  chest  compresses 
the  membrane,  and  thus  the  air  within  the  tambour  is  also  compressed, 

(3.)  A  cannula  or  oesophageal  sound  may  be  introduced  into  that  portion  of  the 
oesophagus  which  lies  in  the  chest,  and  a  connection  established  with  an  Upham'a 
capsule — p.  132  (Rosenthal). 

Marey's  StethOgraph  or  Pneumograph.  — [There  are  two  forms  of  this  instru- 
ment, one  modified  by  P.  Bert  and  the  more  modern  form  (Fig.  102).  A  tambour  {h) 
is  fixed  at  right  angles  to  a  thin  elastic  plate  of  steel  (/).  The  aluminium  disc  on 
the  caoutchouc  of  the  tambour  is  attached  to  an  upright  (b),  whose  end  lies  in  con- 
tact with  a  horizontal  screw  {g).  Two  arms  (d,  c)  are  attached  to  opposite  sides  of 
the  steel  plate,  and  to  them  the  belt  (e)  which  fastens  the  instrument  to  the  chest 
is  attaclied.  When  the  chest  expands  these  two  arms  are  pulled  asunder,  the  steel 
plate  is  bent  and  the  tambour  is  affected,  and  any  movement  of  the  tambour  is 
transmitted  to  a  registering  tambour  by  the  air  in  the  tube  (a).] 

In  the  case  of  animals  placed  on  their  backs,  Snellen  introduced  a  long  needle 
vertically  through  the  abdominal  walls  into  the  liver.  Rosenthal  opened  the 
abdomen  and  applied  a  lever  to  the  under  surface  of  the  diaphragm,  and  thus  regis- 
tered its  movements  (Phrenograph). 


Fig.  104. 


Pneumatogram  obtained  by  means  of  Riegel's  Stethograph — I,  normal  curves;  II, 
curve  from  a  case  of  emphysema;  a,  ascending  limb;  b,  apex;  c,  descending 
limb  of  the  curve.     The  small  elevations  are  due  to  the  cardiac  impulse. 

The  curve  (Fig.  103,  B)  was  obtained  by  placing  the  tambour  of  a 
Brondgeest's  pansphygmograph  upon  the  xiphoid  process,  and  recording 


232  TYPE   OF   RESPIRATION. 

the  movement  upon  a  plate  attached  to  a  vibrating  tuning-fork.  The 
inspiration  (ascending  limb)  begins  with  moderate  rapidity,  is  accelerated 
in  the  middle,  and  towards  the  end  again  becomes  slower.  The  expira- 
tion also  begins  with  moderate  rapidity,  is  then  accelerated,  and  becomes 
much  slower  at  the  latter  part,  so  that  the  curve  falls  very  gradually. 

Inspiration  is  slightly  shorter  than  expiration. — According  to  Sibson, 
the  ratio  for  an  adult  is  as  6  to  7  ;  in  women,  children,  and  old  people, 
6  to  8  or  6  to  9.  Vierordt  found  the  ratio  to  be  10  to  14"1  (to  241); 
J.  E.  Ewald,  1 1  to  1 2,  It  is  only  occasionally  that  cases  occur  where 
inspiration  and  expiration  are  equally  long,  or  where  expiration  is 
shorter  than  inspiration.  When  respiration  proceeds  quietly  and 
regularly,  there  is  usually  no  pause  (complete  rest  of  the  chest-walls) 
"between  the  inspiration  and  expiration  (Riegel).  The  very  flat  part  of 
the  expiratory  curve  has  been  wrongly  regarded  as  due  to  a  pause. 
Of  course,  we  may  make  a  voluntary  pause  between  two  respirations, 
or  at  any  part  of  a  respiratory  act. 

Some  observers,  however,  have  described  a  pause  as  occurring  between  the  end 
of  expiration  and  the  beginning  of  the  next  inspiration  (expiration  pause),  and  also 
another  pause  at  the  end  of  inspiration  (inspiration  pause).  The  latter  is  always 
of  very  short  duration,  and  considerably  shorter  than  the  former. 

During  very  deep  and  slow  respiration,  there  is  usually  an  expiration  pause, 
while  it  is  almost  invariably  absent  during  rapid  breathing.  An  inspiration  pause 
is  always  absent  under  normal  circumstances,  but  it  may  occur  under  pathological 
conditions. 

In  certam  parts  of  the  respiratory  curve  slight  irregularities  may  appear,  which 
are  sometimes  due  to  vibrations  communicated  to  the  thoracic  walls  by  vigorous 
heart-beats  (Fig.  104). 

The  "  type"  of  respiration  may  be  ascertained  by  taking  curves  from 
various  parts  of  the  respiratory  movements.  Hutchinson  showed  that 
in  the  female,  the  thorax  is  dilated  chiefly  by  raising  the  sternum  and 
the  ribs  (Respiratio  costalis),  while  in  man  it  is  caused  chiefly  by  a 
descent  of  the  diaphragm  (Respiratio  diaphragmatica  or  abdominalis). 
In  the  former,  there  is  the  so-called  " costal  tijpe"  in  the  latter  the 
"  abdominal  or  diaphragmatic  type." 

Forced  Bespiration. — This  difference  in  the  type  of  respiration  in  the  sexes 
occurs  only  during  normal  quiet  respiration.  During  deep  Sind.  foi'ced  respiration, 
in  both  sexes  the  dilatation  of  the  chest  is  caused  chiefly  by  raising  the  chest  and 
the  ribs.  In  man,  the  epigastrium  may  be  pulled  in  sooner  than  it  is  protruded. 
During  sleep,  the  type  of  respiration  in  both  sexes  is  thoracic,  while  at  the  same 
time  the  inspiratory  dilatation  of  the  chest  precedes  the  elevation  of  the  abdominal 
wall  (Mosso). 

It  is  not  determined  whether  the  costal  type  of  respiration  in  the  female  depends 
upon  the  constriction  of  the  chest  by  corsets  or  other  causes  (Sibson),  or  whether 
it  is  a  natural  adaptation  to  the  child-bearing  function  in  women  (Hutchinson). 
Some  observers  maintain  that  the  difference  of  type  is  quite  distinct,  even  in  sleep, 
when  all  constrictions  are  removed,  and  that  similar  differences  are  noticeable  in 
young  children.     This  is  denied  by  others,  while  a  third  class  of  observers  hold 


VARIATIONS   OF  THE    RESPIRATORY   MOVEMENTS.  233 

that  the  costal  type  occurs  in  children  of  both  sexes,  and  they  ascribe  as  a  cause 
the  greater  flexibility  of  the  ribs  of  children  and  women,  which  permits  the 
muscles  of  the  chest  to  act  more  efficiently  upon  the  ribs.  [When  a  child  sucks, 
it  breathes  exclusively  through  the  nose,  hence  catarrhal  conditions  of  the  nasal 
mucous  membrane  are  fraught  with  danger  to  the  child.] 

HI.  Pathological  Variations  of  tlie  Respiratory 
Movements. 

I.  Changes  in  the  mode  of  movement- — lu  persons  suffering  from  disease  of 
the  respiratory  organs,  the  dilatation  of  the  chest  may  be  diminished  (to  the 
extent  of  6  or  5  cmtr. )  on  both  sides  or  only  on  one  side.  In  affections  of  the  apex 
of  the  lung  (in  phthisis),  the  sub-normal  expansion  of  the  upper  part  of  the  wall  of 
the  chest  may  be  considerable.  Retraction  of  the  soft  parts  of  the  thoracic  wall, 
the  xiphoid  process  and  the  parts  where  the  lower  ribs  are  inserted,  occurs  in 
cases  where  air  cannot  freely  enter  the  chest  during  inspiration,  e.g.,  in  nar- 
rowing of  the  laiynx;  when  this  retraction  is  confined  to  the  upper  part  of  the 
thoracic  wall,  it  indicates  that  the  portion  of  the  lung  lying  under  the  part  so 
affected  is  less  extensile  and  diseased. 

Harrison's  Groove- — In  persons  sulfering  from  chronic  difficulty  of  breathing, 
and  in  whom,  at  the  same  time,  the  diaphragm  acts  energetically,  there  is  a  slight 
groove  which  passes  horizontally  outwards  from  the  xiphoid  cartilage,  caused  by 
the  pulling  in  of  the  soft  parts  and  corresponding  to  the  insertion  of  the  diaphragm. 

The  duration  of  inspiration  is  lengthened  in  persons  suffering  from  narrowing  of 
the  trachea  or  larynx  ;  expiration  is  lengthened  in  cases  of  dilatation  of  the  lung, 
as  in  emphysema,  where  all  the  expiratory  muscles  must  be  brought  into  action 
(Fig.  104).^ 

II-  Variations  in  the  Rhythm- — When  the  respiratory  apparatus  is  much 
affected,  there  is  either  an  increase  or  a  deepening  of  the  respirations,  or  both. 
AVhen  there  is  gi-eat  difficulty  of  breathing,  this  is  called  Dyspnoea- 

Canses  of  Dyspnoea. — (l)  Limitation  of  the  exchange  of  the  respiratory  gases 
in  the  blood  due  to — (a)  Diminution  of  the  respiratory  surface  (as  in  some  diseases 
of  the  limgs);  (6)  narrowing  of  the  respiratory  passages;  (c)  diminution  of  the  red 
blood-corpuscles;  {d)  disturbances  of  the  respii'atory  mechanism  (e.gr.,  due  to  affec- 
tions of  the  respiratory  muscles  or  nerves,  or  painful  affections  of  the  chest-wall); 
(e)  impeded  cii-culation  through  the  lungs  due  to  various  forms  of  heart-disease. 
(2)  Heat-dyspncea. — The  frequency  of  the  respirations  is  increased  in  febrile  con- 
ditions. The  warm  blood  acts  as  a  dii-ect  irritant  of  the  respiratory  centre  in 
the  medulla  oblongata,  and  raises  the  number  of  respirations  to  30-60  per  minute 
("  Heat-dyspncea '').  If  the  carotids  be  placed  in  warm  tubes,  so  as  to  heat  the 
blood  going  to  the  medulla  oblongata,  the  same  phenomena  are  produced  (A. 
Fick.)     See  also  '' Respiratory  centre'"  (vol.  ii.). 

Cheyne-Stokes'  Phenomenon. — This  remarkable  phenomenon  occurs  in  certain 
diseases,  where  the  normal  supply  of  blood  to  the  brain  is  altered,  or  where  the 
quality  of  the  blood  itself  is  altered,  e.g.,  in  certain  affections  of  the  brain  and  heart, 
and  in  ursemic  poisoning.  Respiratory  pauses  of  one-haK  to  three-quarters  of  a  minute 
alternate  with  a  short  period  (i-j  min.)  of  increased  respii-atory  activity,  and  during 
this  tune  20-30  respirations  occur.  The  respirations  constituting  this  "  series"  are 
shallow  at  first ;  gradually  they  become  deeper  and  more  dyspnoeic,  and  finally 
become  shallow  or  superficial  again.  Then  follows  the  pause,  and  thus  there  is  an 
alternation  of  pauses  and  series  (or  groups)  of  modified  respirations.  During  the 
pause,  the  pupils  are  contracted  and  inactive;  and  when  the  respirations  begin,  they 
dilate  and  become  sensible  to  light ;  the  eyeball  is  moved  as  a  whole  at  the  same 
time  (Leube).    Hein  observed  that  consciousness  was  abolished  during  the  pause. 


234  THE  MUSCLES  OE  RESPIRATION. 

and  that  it  returned  when  respiration  commenced.  A  few  muscular  contractions 
may  occur  towards  the  end  of  the  pause  (rare). 

With  regard  to  the  causes  of  this  phenomenon  there  is  some  doubt.  According  to 
Rosenbach,  the  anomalous  nutrition  of  the  brain  causes  certain  intracranial  centres, 
especially  the  respiratory  centre,  to  be  less  excitable  and  to  be  sooner  exhausted, 
and  this  condition  reaches  its  maximum  during  the  respiratory  pause.  During  the 
pause  these  centres  recover,  and  they  again  become  more  active.  As  soon  as  they  are 
again  exhausted,  their  activity  ceases.  Luciani  also  regards  variations  in  the  ex- 
citability of  the  respiratory  centre  as  the  cause  of  the  phenomenon,  which 
he  compares  with  the  periodic  contraction  of  the  heart  (p.  104).  He  observed 
this  phenomenon  after  injury  to  the  medulla  oblongata  above  the  respiratory 
centre,  and  after  apncea  produced  in  animals  deeply  narcotised  with  opium.  It 
also  occurs  in  the  last  stages  of  asphyxia,  during  respiration  in  a  closed  space, 
Mosso  found  a  similar  phenomenon  normally  in  the  hybernating  dormouse 
(Myoxus.) 

Periodic  BtespiratiOU  of  Frogs, — if  frogs  be  kept  under  water,  or  if  the 
aorta  be  clamped,  after  several  hours,  they  become  passive.  If  they  be  taken  out 
of  the  water,  or  if  the  clamp  be  removed  from  the  aorta,  they  gradually  recover 
and  always  exhibit  the  Cheyne-Stokes'  phenomenon.  In  such  frogs  the  blood- 
current  may  be  arrested  temporarily,  while  the  phenomenon  itself  remains 
(^Sokolow  and  Luchsinger),  If  the  blood-current  be  arrested  by  ligature  of  the 
aorta,  or  if  the  frogs  be  bled,  the  respirations  occur  in  groups.  This  is  followed  by 
a  few  single  respirations,  and  then  the  respiration  ceases  completely.  During  the 
pause  between  the  periods,  mechanical  stimulation  of  the  skin  causes  the  discharge 
of  a  group  of  respirations  (Siebert  and  Langendorff ).  Muscarin  and  digitalin  cause 
periodic  respiration  in  frogs  [which  is  not  due  to  the  action  of  these  drugs  on  the 
heart.] 


112.  General  View  of  the  Respiratory  Muscles. 

(A.)  Inspiration. 

I.  During  Ordinary  Inspiration  are  Active. 

1.  The  diaphragm  {Nervus  phrenicus.) 

2.  The    Mm.   levatores    costarum  longi  et  breves  [Rami  posteriores 
Nn.  dorsalium). 

3.  The  Mm.    intercostales   externi   et  intercartilaginei   {Nn.    inter- 
costales). 

II.  During  Forced  Respiration  are  Active. 

(a.)  Muscles  of  the  Trunk. 

1 .  The  three  Mm.  scaleni  {Rami  musculares  of  the  plexus  cervlcalis  et 
hrachialis). 

2.  M.  sternocleidomastoideus  {Ram.  externus  N.  accessorii). 

3.  M.  trapezius  {R.   externus  N.  accessorii  et  Ram.  musculares  plexus 
cervicalis). 

4.  M.  pectoralis  minor  {Nn.  thoracici  anteriores). 

5.  M,  serratus  posticus  superior  {N  dorsalis  scapulae), 

6.  Mm.  rhomboidei  (iV".  dorsalis  scapulae). 


THE  MUSCLES   OF  FORCED  RESPIRATION.  235 

7.  Mm.  extensores  columnae  vertebralis  [Ram.  posteriores  nervorum 
dorsalium). 

[8.  Mm.  serratus  anticus  major  (A^.  tJioracicus  longus).  1  1] 

(h.)  Muscles  of  the  Larynx. 

1.  M.  sternohyoideus  (Earn,  descendens  hypoglossi). 

2.  M.  sternothyreoideus  {Earn,  descendens  hypoglossi). 

3.  M.  crico-arytaenoideus  posticus  {N.  laryngeus  inferior  vagi). 

4.  M.  thyreo-arytaenoideus  (iV.  laryngeus  inferior  vagi). 

(c.)  Muscles  of  the  Face. 

1.  M.  dilatator  uarium  anterior  et  posterior  (N.  facialis). 

2.  M.  levator  alae  nasi  {N.  facialis'). 

3.  The  dilators  of  the  mouth  and  nares,  during  forced  respiration, 
["gasping  for  breath"]  {N.  facialis). 

{d.)  Muscles  of  the  Pharynx. 

1.  M.  levator  veli  palatini  (iV.  facialis). 

2.  M.  azygos  uvulae  (iV.  facialis). 

3.  According  to  Garland,  the  pharynx  is  always  narrowed. 

(B.)  Expiration. 

I.  During  Ordinary  Respiration. 

The  thoracic  cavity  is  diminished  by  the  weight  of  the  chest,  the 
elasticity  of  the  lungs,  costal  cartilages,  and  abdominal  muscles. 

II.  During  Forced  Expiration. 

The  Abdominal  Muscles. 

1.  The  abdominal  muscles  [including  the  obliquus  externus  and 
internus,  and  transversalis  abdominis]  (7V?2.  ahdominis  internis  anteriwes 
e  nervis  inter costalibus,  8-1 2). 

2.  Mm.  intercostales  interni,  so  far  as  they  lie  between  the  osseous 
ribs,  and  the  Mm.  infracostales  {N'n.  intercostales). 

3.  M.  triangularis  sterni  {Nn.  intercostales). 

4.  M.  serratus  posticus  inferior  (Earn,  externi  nerv.  dorsalium). 

5.  M.  quadratus  lumborum  {Ram.  muscular  e  plexu  lumhali). 

113.  Action  of  the  Individual  Respiratory  Muscles. 

(A.)  Inspiration.— (1.)  The  Diaphragm  arises  from  the  cartilages  and  the 
adjoining  osseous  parts  of  the  lower  six  ribs  (costal  portion),  by  two  thick  processes 
or  crura  from  the  upper  three  or  four  lumbar  vertebrae,  and  a  sternal  portion  from 
the  back  of  the  ensiform  process. 


236 


THE  ACTION   OF  THE  DIAPHRAGM. 


It  represents  an  arched  double  cupola  or  dome-shaped  partition,  directed  towards 
the  chest ;  in  the  larger  concavity  on  the  right  side  lies  the  liver,  while  the  smaller 
arch  on  the  left  side  is  occupied  by  the  spleen  and  stomach.  During  the  passive 
condition,  these  viscera  are  pressed  against  the  under  surface  of  the  diaphragm,  by 
the  elasticity  of  the  abdominal  waUs  and  by  the  intra-abdominal  pressure,  so  that 
the  arch  of  the  diaphragm  is  pressed  upwards  into  the  chest.  The  elastic  traction 
of  the  lungs  also  aids  in  producing  this  result.  The  greater  part  of  the  upper  surface 
of  the  central  tendon  of  the  diaphragm  is  united  to  the  pericardium.  The  part  on 
which  the  heart  rests,  and  which  is  perforated  by  the  inferior  vena  cava  (foramen 
quadrilaterum)  is  the  deepest  part  of  the  middle  portion  of  the  diaphragm  during 
the  passive  condition. 

Action  of  the  Diaphragm. — When  the  diaphragm  contracts,  both 
arched  portions  become  flatter,  and  the  chest  is  thereby  elongated  from 
above  downwards.  In  this  act,  the  lateral  muscular  parts  of  the 
diaphragm  pass  from  an  arched  condition  into  a  flatter  form  (Fig.  105), 

and  during  a  forced  inspiration, 
the  lowest  lateral  portions,  which 
during  rest  are  in  contact  with 
the  chest-wall,  become  separated 
from  it.  The  middle  of  the  cen- 
tral tendon  where  the  heart  rests 
(fixed  by  means  of  the  pericardium 
and  inferior  vena  cava)  takes  no 
share  in  this  movement;  hence, 
this  part  is  highest  in  the  thorax 
during  a  forced  inspiration. 

Undoubtedly,  the  diaphragm  is 
the  most  powerful  agent  in  in- 
creasing the  cavity  of  the  chest. 
Briicke,  in  fact,  believes  that  in 
addition  to  increasing  the  length 
of  the  thoracic  cavity  from  above 
downwards,  it  also  increases  the 
transverse  diameter  of  the  lower 
part  of  the  chest.  It  presses  upon 
the  abdominal  viscera  from  above, 
and  strives  to  press  these  out- 
wards, thus  tending  to  push  out 
the  adjoining  thoracic  wall. 

If  the  contents  of  the  abdomen  are 


Fig.  105. 
Sagittal  section  through  the  second  rib 
on  the  right  side.  This  figure  shows 
that  when  the  arched  muscular  part 
of  the  diaphragm  contracts,  a  wedge- 
shaped  space,  M'ith  its  apex  down- 
wards, is  formed  around  the  circum- 
ference of  the  lower  part  of  the  chest, 
so  that  the  chest  is  enlarged  from 
above  downwards. 


removed  from  a  living  animal,  every 
time  the  diaphragm  contracts,  the  ribs  are  drawn  inwards  (Haller).  This,  of 
course,  hinders  the  chest  from  becoming  wdder  below,  hence  the  presence  of  the 
abdominal  viscera  seems  to  be  necessary  for  the  normal  activity  of  the  diaphragm. 
The  immense  importance  of  the  diaphragm  as  the  great  inspiratory  muscle  is 
proved  by  the  fact  that,  after  both  phrenic  nerves  (third  and  fourth  cervica  nerves) 


THE  ELEVATORS   OF  THE  RIBS. 


237 


are  divided,  death  occurs  (Budge,  Eulenkamp).  The  phrenic  nerve  contains  some 
sensory  fibres  for  the  pleura,  pericardium,  and  a  portion  of  the  diaphragm 
(Schreiber,  Henle,  Schwalbe). 

The  contraction  of  the  diaphragm  is  not  to  be  regarded  as  a  "  simple  muscular 
contraction, "  since  it  lasts  4  to  8  times  longer  tlian  a  simple  contraction ;  it  is  rather 
a  short  tetanic  contraction,  which  we  may  arrest  at  any  stage  of  its  activity  without 
bringing  into  action  any  antagonistic  muscles  (Kronecker  and  Marckwald), 

(2.)  The  Elevators  of  the  Kibs. — The  ribs  at  their  vertebral  ends  (which  lie 
much  higher  than  their  sternal  ends)  are  united  by  means  of  joints  by  their  heads 
and  tubercles  to  the  bodies  and  transverse  processes  of  the  vertebrte.  A  horizontal 
axis  can  be  drawn  through  both  joints,  around  which  the  ribs  can  rotate  upwards 
and  downwards.  If  the  axes  of  rotation  of  each  pair  of  ribs  be  prolonged  on  both 
sides  until  they  meet  in  the  middle  line,  the  angles  so  formed  are  greatest  above 
(125°),  and  smaller  below  (88°)  (A.  W.  Volkmann).  Owing  to  the  ribs  being 
curved,  we  can  imagine  a  plane  which,  in  the  passive  (expiratory)  condition  of  the 
chest,  has  a  slope  from  behind  and  inwards  to  the  front  and  outwards.  If  the 
ribs  move  on  their  axis  of  rotation  this  plane  becomes  more  horizontal,  and  the 
thoracic  cavity  is  increased  in  its  transverse  diameter.  As  the  axis  of  rotation  of 
the  upper  ribs  runs  in  a  more  frontal,  and  that  of  the  lower  ribs  in  a  more  sagittal, 
direction,  the  elevation  of  the  upper  ribs  causes  a  greater  increase  from  before 
backwards,  and  the  lower  ribs  from  within  outwards  (as  the  movements  of  ribs 
which  are  directed  downwards  are  vertical  to  the  axis).  The  costal  cartilages 
undergo  a  slight  tension  at  the  same  time,  which  brings  their  elasticity  into  play. 


\ 

\ 

8 

Fig.  106. 
Scheme  of  the  action  of  the  intercostal  muscles. 

Changes  in  the  Chest. — All "  inspiratory  muscles"  which  act  directly 
upon  the  chest-wall,  do  so  hy  raising  the  ribs: — {a)  When  the  ribs  are 


238  THE  ACTION   OF  THE   INTERCOSTAL  MUSCLES. 

raised,  the  intercostal  spaces  are  widened.  (5.)  When  the  upper  ribs 
are  raised,  all  the  lower  ribs  and  the  sternum  must  be  elevated  at  the 
same  time,  because  all  the  ribs  are  connected  with  each  other  by  means 
of  the  soft  parts  of  the  intercostal  spaces,  (c)  During  inspiration, 
there  is  an  elevation  of  the  ribs  and  a  dilatation  of  the  intercostal 
spaces.  (The  lowest  rib  is  an  exception;  during  forced  respiration,  at 
least,  it  is  drawn  downwards),  (d.)  If,  on  a  preparation  of  the 
chest,  the  ribs  be  raised  as  in  inspiration,  we  may  regard  all  those 
muscles  as  elevators  of  the  ribs,  whose  origin  and  insertion  become 
approximated.  Everyone  is  agreed  that  the  scaleni  and  levatmxs 
cosfarum  longi  el  breves,  the  serratus  posticus  superior,  are  inspiratory 
muscles.  These  are  the  most  important  inspiratory  muscles  which 
act  upon  the  ribs. 

Intercostal  Muscles. — With  regard  to  the  action  of  the  intercostal 
muscles,  there  is  a  great  difference  of  opinion.  According  to  the 
above  experiment,  the  external  intercostals  and  the  intercartilaginous 
parts  of  the  internal  intercostals  act  as  inspiratory  muscles,  whilst  the 
remaining  portions  of  the  internal  intercostals  (as  far  as  they  are 
covered  by  the  external)  are  elongated  when  the  ribs  are  raised,  while 
they  shorten  when  the  chest-wall  descends.  A  muscle  shortens  only 
during  its  activity.  The  internal  intercostals  were  regarded  by  Ham- 
berger  (1727)  as  depressors  of  the  ribs  or  expiratory  muscles. 

Id  Fig.  106,  I,  when  the  rods,  a  and  h  (which  represent  the  ribs)  are  raised,  the 
intercostal  space  must  be  widened  (fif>'  c  d).  On  the  opposite  side  of  the  figure, 
it  is  evident  that  when  the  rods  are  raised,  the  line,  g  h,  is  shortened  (ik-^zgh, 
direction  of  the  external  intercostals) — I  m  is  lengthened  (Int'czon,  direction  of 
internal  intercostals).  Fig.  106,  II,  shows,  that  whenj^the  ribs  are  raised,  the  inter- 
cartilaginei,  indicated  by  g  h,  and  the  external  intercostals,  indicated  by  Z  k,  are 
shortened.  When  the  ribs  are  raised,  the  position  of  the  muscular  fibres  is 
indicated  by  the  diagonal  of  the  rhomb  becoming  shorter. 

The  mode  of  action  of  the  intercostal  muscles  is  an  old  story.  Galen  (131-203 
A.D.)  regarded  the  externals  as  inspiratory,  the  internals  as  expiratory.  Hamberger 
(1727)  accepted  this  proposition  and  considered  the  intercartilaginei  also  as  inspira- 
tory. Haller  took  both  the  external  and  internal  intercostals  as  inspiratory,  while 
Vesalius  (1540)  regarded  both  as  expiratory.  Landerer  observing  that  the  upper 
two  or  three  intercostal  spaces  became  narrower  during  inspiration,  regarded  both 
as  active  during  inspiration  and  expiration.  They  keep  one  rib  attached  to  the 
other,  so  that  their  action  is  to  transmit  any  strain  put  upon  them  to  the  wall  of 
the  chest.  On  this  view  they  will  be  in  action,  even  when  the  distance  between 
their  points  of  attachment  becomes  greater.  Laudois  regards  the  external  inter- 
costals and  intercartilaginei  as  active  only  during  inspiration,  the  internal 
intercostals  only  during  expiration.  [Martin  and  Hartwell  exposed  the  internal 
intercostals  and  observed  whether  they  contracted  along  with  the  diaphragm,  or 
whether  the  contractions  of  these  two  muscles  alternate.  As  the  result  of  their 
experiments,  they  conclude  that  "the  internal  intercostal  muscles  are  expiratory 
throughout  their  whole  extent,  at  least  in  the  dog  and  cat;  and  that  in  the  former 
animal  they  are  almost  '  ordinary '  muscles  of  respiration,  while  in  the  latter  they 
are  'extraordinary'  respiratory  muscles."]    Landois  is  of  opinion  that  the  chief 


MECHANISM   OF   ORDINARY   EXPIRATION.  239 

action  of  these  muscles  is  not  to  raise  or  depress  the  ribs,  but  rather  that  the 
external  intercostals  and  the  intercartilaginei  offer  resistance  to  the  inspiratory 
dilatation  of  the  intercostal  spaces  and  to  the  simultaneously  increased  elastic  ten- 
sion of  the  lungs.  Internal  intercostals  act  during  powerful  expiratory  efforts, 
{e.g.,  coughing),  and  oppose  the  distension  of  the  lungs  and  chest  caused  by  this 
act.  Unless  muscles  were  present  to  resist  the  uninterrupted  tension  and  pressure, 
the  intercostal  substance  would  become  so  distended  that  respiration  would  be 
impossible,  [Accordmg  to  Rutherford,  the  internal  intercostals  are  probably 
muscles  of  inspii-ation.] 

The  Pectoralis  Minor  and  (1  Serratus  Anticns  Major)  can  only  act 
as  elevators  of  the  ribs,  when  the  shoulders  are  fixed,  partly  by  the  rhom- 
boidei,  and  partly  by  fixing  the  shoulder- joint  and  supporting  the  arms, 
as  is  done  instinctively  by  persons  suffering  from  breathlessness. 

(3.)  Muscles  acting  upon  the  Sternum,  Clavicle  and  Vertebral  Column. 
— When  the  head  is  fixed  by  the  muscles  of  the  neck,  the  sternocleido- 
mastoid can  raise  the  manubrium  sterni,  and  the  sternal  end  of  the 
clavicle,  so  that  the  thorax  is  raised  and  thereby  dilated.  The  scaleni 
also  aid  in  this  act.  The  clavicular  portion  of  the  trapezius  may 
act  in  a  similar,  although  less  energetic,  manner.  When  the  vertebral 
column  is  straightened,  it  causes  an  elevation  of  the  upper  ribs,  and  a 
dilatation  of  the  intercostal  spaces  which  aid  inspiration.  During  deep 
respiration,  this  straightening  of  the  vertebral  column  takes  place  in- 
voluntarily. 

(4.)  Laryngeal  Movements. — During  laboured  respiration,  with  every 
inspiration,  the  larynx  descends  and  the  glottis  is  opened.  At  the 
same  time  the  palate  is  raised,  so  as  to  permit  a  free  passage  to  the 
air  entering  through  the  mouth. 

(5.)  Facial  Movements. — During  laboured  respiration,  the  facial 
muscles  are  involved ;  there  is  an  inspiratory  dilatation  of  the  nostrils 
(well  marked  in  the  horse  and  rabbit.)  When  the  need  for  respiration 
is  very  great,  the  mouth  is  gradually  widened,  and  the  person  as  it  were 
gasps  for  breath.  During  expiration,  the  muscles  that  are  active  during 
4  and  5  relax,  so  that  a  position  of  equilibrium  is  established  without 
there  being  any  active  expiratory  movement  to  counteract  the  inspira- 
tory movement.  During  inspiration  the  pharynx  becomes  narrower 
(Garland.) 

(B.)  Expiration. — Ordinary  expiration  occurs  without  the  aid  of 
muscles,  owing  to  the  iveight  of  the  chest,  which  tends  to  fall  into  its 
normal  position  from  the  position  to  which  it  was  raised  during  inspira- 
tion. This  is  aided  by  the  elasticity  of  the  various  parts  of  the  chest. 
When  the  costal  cartilages  are  raised,  which  is  accompanied  by  a  slight 
rotation  of  their  lower  margins  from  below  forwards  and  upwards 
their  elasticity  is  called  into  play.  As  soon,  therefore,  as  the  inspira- 
tory forces  cease,  the  costal  cartilages  return  to  their  normal  position 


240  MUSCLES   OF  FORCED   EXPIRATION. 

— i.e.,  the  position  of  expiration — and  tend  to  untwist  themselves ;  at 
the  same  time,  the  elasticity  of  the  distended  lungs  draws  upon  the 
thoracic  walls  and  the  diaphragm.  Lastly,  the  tense  and  elastic 
abdominal  walls,  which,  in  man  chiefly,  are  stretched  and  pushed 
forward,  tend  to  return  to  their  non-distended  passive  condition  when 
the  abdominal  viscera  are  relieved  from  the  pressure  of  the  contracted 
diaphragm.  ("When  the  position  of  the  body  is  reversed,  the  action 
of  the  weight  of  the  chest  is  removed,  but  in  place  of  it,  there  is  the 
weight  of  the  viscera,  which  press  upon  the  diaphragm.) 

The  abdominal  muscles  [obliquus  internus  and  extemus,  trans- 
versalis  abdominis  and  levator  ani]  are  always  active  during  laboured 
respiration.  They  act  by  diminishing  the  abdominal  cavity,  and  they 
press  the  abdominal  contents  upwards  against  the  diaphragm.  When 
they  act  simultaneously,  the  abdominal  cavity  is  diminished  throughout . 
its  whole  extent.  The  Triangularis  sterni  depresses  the  sternal  ends 
of  the  united  cartUages  and  bones,  from  the  third  to  sixth  ribs  down- 
wards ;  and  the  Serratus  posticus  inferior  depresses  the  four  lowest 
ribs,  causing  the  others  to  follow.  It  is  aided  by  the  duadratas 
lumborum,  which  depresses  the  last  rib.  According  to  Henle,  the 
serratus  posticus  inferior  fixes  the  lower  ribs  for  the  action  of  the  slips 
of  the  diaphragm  inserted  into  them,  so  that  it  acts  during  inspiration. 
According  to  Landerer,  the  downward  movement  of  the  ribs  in  the 
lower  part  of  the  thorax  dilates  the  chest. 

In  the  erect  position,  when  the  vertebral  column  is  fixed,  deep  inspiration  and 
expiration  naturally  alter  the  position  of  the  centre  of  gravity,  so  that  during 
inspiration,  owing  to  the  protrusion  of  the  thoracic  and  abdominal  walls,  the 
centre  of  gravity  lies  somewhat  more  to  the  front.  Hence,  with  each  respiration 
there  is  an  involuntary  balancing  of  the  body.  During  very  deep  inspiration,  the 
accompanying  straightening  of  the  vertebral  column  and  the  throwing  backwards 
of  the  head  compensate  for  the  protrusion  of  the  anterior  walls  of  the  trunk. 

114.  Relative  Dimensions  of  the  Chest. 

It  is  important,  from  a  physician's  point  of  view,  to  know  the  dimensions  of  the 
thorax,  and  also  the  variations  it  undergoes  at  different  parts.  The  diameter  of 
the  chest  is  ascertaiQed  by  means  of  callipers ;  the  circumference  with  a  flexible 
centimetre  or  other  measure. 

In  strong  men,  the  circumference  of  the  upper  part  of  the  chest 
(immediately  under  the  arms)  is  88  centimetres  (34'3  inches),  in 
females  82  centimetres  (32  inches);  on  the  level  of  the  ensiform  process 
82  centimetres  (32  inches)  and  78  centimetres (30-4  inches)  respectively. 
WTien  the  arms  are  placed  horizontally,  during  the  phase  of  moderate 
expiration,  the  circumference  immediately  under  the  nipple  and  the 
angles  of  the  scapulae  is  equal  to  half  the  length  of  the  body;  in  man 


RELATIVE  DIMENSIONS   OF  THE  CHEST. 


241 


82,  and  during  deep  inspiration  89  centimetres.  The  circumference  at 
the  level  of  the  ensiform  cartilage  is  6  centimetres  less.  In  old  people, 
the  circumference  of  the  upper  part  of  the  chest  is  diminished,  so  that 
the  lower  part  becomes  the  wider  of  the  two.  The  right  half  of  the 
chest  is  usually  slightly  larger  than  the  left  half,  owing  to  the  greater 
development  of  the  muscles  on  that  side.  The  long  diameter  of  the 
chest — from  the  clavicle  to  the  margin  of  the  lowest  rib — varies  very 
much. 

The  transverse  diameter  in  man  above  and  below  is  25-26  centi- 
metres (9-7-10-1  inches),  in  females  23-24  centimetres  (8-9-9-2 
inches) ;    above  the    nipple    it  is    1    centimetre  more.      The  antero- 


Fi^.  107. 

Curve  taken  with  the  cyrtometer  —  Left  side  of  the  chest  retracted  in  a  girl  twelve 
years  of  age  (Eichhorst). 


posterior  diameter  (distance  of  anterior  chesfc-wall  from  the  tip  of  a 
spinous  process)  in  the  upper  part  of  the  chest  is  =  17  (6'Q  inches), 
in  the  lower  19  centimetres  (7  "4  inches).  Valentin  found,  that  in  man 
during  the  deepest  inspiration  the  chest  on  a  level  with  the  groove  in 
the  heart  was  increased  about  ^^  to  -f;  while  Sibson  estimates  the 
increase  at  the  level  of  the  nipple  to  be  yV- 


ThoracO-meter. — In  order  to  obtain  a  knowledge  of  the  degree  of  movement— 
rising  or  falling — of  the  chest-wall  during  respiration,  various  instruments  have 
been  invented.  The  thoraco-meter  of  Sibson  (Fig.  108)  measures  the  elevation  in 
different  parts  of  the  sternum.  It  consists  of  two  metallic  bars  placed  at  right 
angles  to  each  other;  one  of  them,  A,  is  placed  on  the  vertebral  column.  On  B 
there  is  placed  a  movable  transverse  bar,  C,  which  carries  on  its  free-end  a  toothed 
rod,  Z,  directed  downwards.  The  lower  end  of  this  rod  is  provided  with  a  pad 
which  rests  on  the  sternum,  while  its  toothed  edge  drives  a  small  wheel  which 

16 


242 


LIMITS   OF  THE   LUNGS. 


moves  au  index,  whose  excursions  are  indicated  on  a  circle  with  a  scale  attached 
to  it. 

The    Cyrtometer    of 

Woillez  is  very  useful.  A 
brass  chain,  composed  of 
movable  links,  is  applied  in 
a  definite  direction  to  part 
of  the  chest-wall,  e.g.,  trans- 
versely on  a  level  with  the 
nipple,  or  vertically  upon 
the  mammillary  or  axillary 
lines  anteriorly.  There  are 
freely  movable  links  at  two 
parts  which  permit  the  chain 
to  be  easily  removed,  so  that 
as  a  whole  it  still  retains  its 
form.  The  chain  is  laid 
upon  a  sheet  of  paper,  and 
a  line  drawn  with  a  pencil 
around  its  inner  margin  gives 
the  form  of  the  thorax  (Fig. 
107). 


Fig.  108. 
Sibson's  Thoraco-meter. 


Limits  of  the  Lungs. — The  extent  and  boundaries  of  the  lungs  are 
ascertained  in  the  living  subject  by  means  of  Percussion,  which  consists 
in  lightly  tapping  the  chest-wall  by  means  of  a  hammer  (percussion- 
hammer).  A  small  ivory  or  bony  plate  (plezimeter),  held  in  the 
left-hand,  is  laid  on  the  chest,  and  the  hammer  is  made  to  strike  this 
plate,  whereby  a  sound  is  emitted,  which  sound  varies  with  the  con- 
dition of  the  subjacent  lung-tissue.  Wherever  the  lung  substance  in 
contact  with  the  chest-wall  contains  air,  a  clear  resonant  tone  or  sound 
— such  as  is  obtained  by  striking  a  vessel  containing  air,  a  clear 
percussion  sound — is  obtained.  Where  the  lung  does  not  contain  air, 
a  dull  sound — like  striking  a  limb — is  obtained.  If  the  parts  containing 
air  be  very  thin,  or  are  only  partially  filled  with  air,  the  sound  is 
"muffled." 

Pig.  109,  along  with  Fig.  31,  indicate  the  relations  of  the  lungs  to 
the  anterior  surface  of  the  chest.  The  apices  of  the  lungs  reach  3-7 
centimetres  (l-l-2'7  inches)  above  the  clavicles  anteriorly,  while 
posteriorly  they  extend  from  the  spines  of  the  scapulae  as  high  as  the 
seventh  spinous  process.  The  lower  margin  of  the  right  lung  in  the 
passive  position  (moderate  expiration)  of  the  chest,  commences  at  the 
right  margin  of  the  sternum  at  the  insertion  of  the  sixth  rib,  runs  under 
the  right  nipple,  nearly  parallel  to  the  upper  border  of  the  sixth  rib, 
and  descends  a  little  in  the  axillary  Hne,  to  the  upper  margin  of  the 
seventh  rib.  On  the  left  side  (apart  from  the  position  of  the  heart),  the 
lower  limit  reaches  as  far  down  anteriorly  as  the  right.  In  Fig.  109 
the  line,  a,  t,  h,  shows  the  lowest  limit  of  the  passive  lungs.     Posteriorly, 


LIMITS   OF  THE   LUNGS. 


243 


both  lungs  reach  as  far  down  as  the  tenth  rib.  During  the  deepest 
inspiration,  the  lungs  descend  anteriorly  as  far  as  between  the  sixth  and 
seventh  ribs,  and  posteriorly  to  the  eleventh  rib — whereby  the 
diaphragm  is  separated  from  the  thoracic  ^jwall  (Fig.  105).  During  the 
deepest  expiration,  the  lower  margins  of  the  lungs  are  elevated  almost 
as  much  as  they  descend  during  inspiration.  In  Fig.  109,  m,  n,  indicates 
the  margin  of  the  right  lung  during  deep  inspiration ;  h,  I,  during  deep 
expiration. 

It  is  important  to  observe  the  relation  of  the  margin  of  the  left  lung 


Fig.  109. 

Topography  of  the  lungs  aud  heart  during  inspiration  and  expiration  (v.  Dusch) — 
h,  I,  upward  limit  of  margin  of  lung  during  deepest  expiration;  m,  n,  lower 
limit  during  deepest  inspiration;  t,  t',  t",  triangular  area  where  the  heart  is 
uncovered  by  lung,  dull  percussion  sound;  d,  d',  d",  muffled  percussion 
sound;  i,  i',  anterior  margin  of  left  lung  reaches  this  line  during  deep  inspira- 
tion, and  during  deep  expiration  it  recedes  as  far  as  e,  e'. 

to  the  heart.  In  Fig.  109,  a  somewhat  triangular  space,  reaching  from 
the  middle  of  the  point  of  insertion  of  the  fourth  rib  to  the  sixth  rib  on 
the  left  side  of  the  sternum,  is  indicated.  In  the  passive  chest,  the  heart 
lies  in  contact  with  the  thoracic  wall  in  this  triangular  area.  This  area 
is  represented  by  the  triangle,  t,  t',  t",  and  percussion  over  it  gives  a 
dull  sound  (superficial  dulness). 

In  the  area  of  the  larger  triangle,  d,  d',  d",  where  the  heart  is 


244      PATHOLOGICAL  VARIATIONS   OP  THE   PERCUSSION   SOUNDS. 

separated  from  the  chest-wall  by  the  thin  anterior  margins  of  the  lung, 
percussion  gives  a  muffled  sound,  while  further  outwards  a  clear  lung 
percussion  sound  is  obtained.  During  deep  inspiration,  the  inner 
margin  of  the  left  lunar  reaches  over  the  heart  as  far  as  the  insertion 
of  the  mediastinum,  whereby  the  dull  sound  is  limited  to  the  smallest 
triangle,  t,  i,  i'.  Conversely,  during  very  complete  expiration,  the 
margin  of  the  lung  recedes  so  far  that  the  cardiac  dulness  embraces 
the  space,  t,  e,  e. 


115.  Pathological  Variations  of  the  Percussion 

Sounds. 

The  normal  clear  resonant  percussion  sound  of  the  lungs  becomes  muffled  when 
infiltration  takes  place  into  the  lungs,  so  as  to  diminish  the  normal  amount  of  air 
within  them,  or  when  the  lungs  are  compressed  from  without,  e.g.,  by  efi"usion  of 
fluid  iuto  the  pleura.  The  percussion  sound  becomes  clearer  when  the  chest-wall 
is  very  thiu,  as  in  spare  individuals  during  very  deep  inspiration,  and  especially 
in  emphysema,  where  the  air-vesicles  of  certain  parts  of  the  lung  (apices  and 
margins)  become  greatly  dilated. 

The  pitch  of  the  percussion  sound  ought  also  to  be  noted.  It  depends  upon  the 
greater  or  less  tension  of  the  elastic  pulmonary  tissue,  and  on  the  elasticity  of  the 
thoracic  wall.  The  tension  of  the  elastic  tissue  is  increased  during  inspiration  and 
diminished  during  expiration,  so  that  even  under  physiological  conditions,  the 
pitch  of  the  sound  varies. 

The  sound  is  said  to  be  tympanitic  (Skoda)  when  it  has  a  musical  quality 
resembling  the  timbre  of  a  sound  produced  on  a  drum,  and  when  it  has  a  slight 
variation  in  pitch.  If  a  caoutchouc  ball  be  placed  near  the  ear,  on  tapping  it 
gently,  a  well-marked  tympanitic  sound  is  heard,  and  the  sound  is  of  higher  pitch 
the  smaller  the  diameter  of  the  ball.  A  tympanitic  sound  is  always  produced 
on  tapping  the  trachea  in  the  neck.  A  tympanitic  sound  produced  over  the 
chest  is  always  indicative  of  a  diseased  condition.  It  occurs  in  cases  of  cavities 
or  vomicse  within  the  substance  of  the  lung  (the  sound  becomes  deeper  when  the 
mouth,  or,  better,  the  mouth  and  nose,  are  closed),  when  air  is  present  in  one 
pleural  cavity,  as  well  as  in  conditions  where  the  tension  of  the  pulmonary  tissues 
is  diminished.  The  tympanitic  sound  resembles  the  metallic  tinkling  which  is 
heard  in  large  pathological  cavities  in  the  lungs,  or  which  occurs  when  the  pleural 
cavity  contains  air,  and  when  the  conditions  which  permit  a  more  uniform  reflec- 
tion of  the  sound-waves  within  the  cavity  are  present. 

When  percussing  a  chest,  we  may  determine  whether  the  substance  lying  under 
the  portion  of  the  chest  under  examination  presents  great  or  small  resistance  to 
the  blow,  either  of  the  percussion-hammer  or  of  the  tips  of  the  fingers,  as  the  case 
may  be. 

Phonometry.— If  the  stem  of  a  vibrating  tuning-fork  be  placed  on  the  chest- 
wall  over  a  part  containing  air,  its  sound  is  intensified ;  but  if  it  be  placed  over  a 
portion  of  the  lung  which  contains  little  or  no  air  its  sound  is  enfeebled  (von 
Baas). 

Historical. — The  actual  discoverer  of  the  art  of  percussion  was  Auenbrugger 
(tl809).  Piorry  and  Skoda  developed  the  art  and  theory  of  percussion,  while 
Skoda  originated  and  developed  the  physical  theory  (1839). 


THE   NORMAL   RESPIRATORY   SOUNDS.  245 


116.  The  Normal  Respiratory  Sounds. 

Normal  Vesicular  Soxmd. — If  the  ear  directly,  or  through  the 
medium  of  a  stethoscope,  be  placed  in  connection  with  the  chest-wall, 
we  hear  over  the  entire  area,  where  the  lung  is  in  contact  with  the 
chest,  the  so-called  'Vesicular"  sound,  which  is  audible  mly  during 
inspiration.  It  is  a  fine  sighing  or  rustling  sound.  It  is  said  to  be 
caused  by  the  sudJen  dilatation  of  the  air-vesicles  (hence  "vesicular") 
during  inspiration,  and  it  is  also  ascribed  to  the  friction  of  the  current 
of  air  entering  the  alveoli. 

The  sound  has,  at  one  time,  a  soft,  at  another,  a  sharper  character; 
the  latter  occurs  constantly  in  children  up  to  12  years  of  age.  In 
their  case,  the  sound  is  sharper,  because  the  air,  in  entering  vesicles  one- 
third  narrower,  is  subjected  to  greater  friction.  As  the  air  passes  out 
of  the  air-vesicles  during  expiration,  it  gives  rise  to  a  feeble  sighing 
sound  of  an  indistinct  soft  character. 

Bronchial  Respiration. — "Within  the  larger  air-passages — larynx, 
trachea,  bronchi — during  inspiration  and  expiration,  there  are  loud 
sounds  like  a  sharp  h  or  ch — the  "  hronchiaV — the  laryngeal,  tracheal, 
or  "  tubular"  sound,  or  breathing.  This  sound  is  also  heard  between 
the  scapulae,  at  the  level  of  the  fourth  dorsal  vertebra  (bifurcation  of 
trachea),  and  it  occurs  also  during  expiration,  being  slightly  louder  on 
the  right  side,  owing  to  the  slightly  greater  calibre  of  the  right 
bronchus. 

At  all  other  parts  of  the  chest,  the  vesicular  sound  obscures  the 
tubular  or  bronchial  sound.  If  the  air-vesicles  are  deprived  of  their 
air,  the  tubular  breathing  becomes  distinct.  It  is  asserted  that,  when 
lungs  containing  air  are  placed  over  the  trachea,  the  tubular  sound 
there  produced  becomes  vesicular.  In  this  case,  we  must  suppose 
that  the  vesicular  sound  arises  from  the  tubular  breathing  becoming 
weakened,  and  being  acoustically  altered,  by  being  conducted  through 
the  lung  alveoli  (Baas,  Penzoldt).  A  sighing  sound  is  often  produced 
at  the  apertures  of  the  nose  and  mouth  during  forced  respiration. 

117.  Pathological  Respiratory  Sounds. 

Historical. — Although  several  abnonnal  sounds  in  connection  with  diseases  of 
the  respiratory  organs  were  kno\m  to  Hippocrates  (succussion-sound,  friction,  and 
several  catarrhal  sounds),  still,  Laennec  was  the  discoverer  of  the  method  of 
auscultation  (1S16),  while  Skoda  greatly  extended  our  knowledge  of  its  facts. 

(1.)  Bronchial  breathing  occurs  over  the  entire  area  of  the  lung,  either  when 
the  air- vesicles  are  devoid  of  air,  which  may  be  caused  by  the  exudation  of  fluid 
or  solid  constituents,  or  when  the  lungs  are  compressed  from  without.     In  both 


246  PATHOLOGICAL   RESPIRATORY   SOUNDS. 

cases  vesicular  sounds  disappear,  and  the  condensed  or  solidified  lung- tissue  conducts 
the  tubular  sound  of  the  large  bronchi  to  the  surface  of  the  chest.  It  also  occurs 
in  large  cavities,  with  resistant  walls  near  the  surface  of  the  lung,  provided  these 
cavities  communicate  with  a  large  bronchus. 

(2.)  The  amphoric  sound  is  compared  to  that  produced  by  blowing  over  the 
mouth  of  an  empty  bottle.  It  occurs  either  when  a  cavity — at  least  the  size  of 
the  fist — exists  in  the  lung,  which  is  so  blown  into  during  respiration  that  a 
peculiar  amphoric-like  sound  with  a  metallic  timbre  is  produced;  or  when  the 
lung  still  contains  air,  and  is  capable  of  expansion;  as  there  is  still  air  in  the 
pleural  cavity,  it  acts  as  a  resonator,  and  causes  an  amphoric  sound,  simultaneous 
with  the  change  of  air  in  the  lungs. 

(3.)  If  obstruction  occurs  in  the  course  of  the  air-passages  of  the  lungs,  various 
results  may  accrue,  according  to  the  nature  of  the  resistance: — {a.)  owing  to  various 
causes,  e.g.,  in  the  apices  of  the  lungs  there  may  be  partial  swelling  of  the  walls 
of  the  air- tubes,  or  infiltration  into  the  air-cells  which  hinders  the  regular  supply  of 
air.  In  these  cases,  parts  of  the  lung  are  not  supplied  with  air  contmuously ;  it 
only  reaches  them  periodically.  In  these  cases  a  cog-wheel  sound  occurs.  A 
similar  sound  may  be  heard  occasionally  in  a  normal  lung,  when  the  muscles  of 
the  chest  contract  in  a  periodic  spasmodic  manner.  (&. )  When  the  air  entering 
large  bronchi  causes  the  formation  of  bubbles  in  the  mucus  which  may  have 
accumulated  there,  "mucous  rales"  are  produced.  They  also  occur  in  small 
spaces  when  the  walls  are  separated  from  their  fluid  contents  by  the  air  entering 
during  inspiration,  or  when  the  walls,  being  adherent  to  each  other,  are  suddenly 
pulled  asunder.  The  rales  are  distinguished  as  moist  (when  the  contents  are 
fluid),  or  as  dry  (when  the  contents  are  sticky);  they  may  be  inspiratory, 
expiratory,  or  continuous,  or  they  may  be  coarse  or  fine;  further,  there  is  the 
very  fine  crepitation  or  crackling  sound,  and  lastly,  the  metallic  tinkling  caused 
in  large  cavities  through  resonance,  (c.)  When  the  mucous  membrane  of  the 
bronchi  is  greatly  swollen,  or  is  so  covered  with  mucus  that  the  air  must  force  its 
way  through,  deep  sonorous  ronchi  (ronchi  sonori)  may  occur  in  the  large  air- 
passages,  and  clear  shrill  sibillant  sounds  (ronchi  sibilantes)  in  the  smaller  ones. 
When  there  is  extensive  bronchial  catarrh,  not  unfrequently  we  feel  the  chest- 
wall  vibrating  with  the  rale  sounds  (^Bronchial  fremitus). 

(4. )  If  fluid  and  air  occur  together  in  one  pleural  cavity  in  which  the  lung  is 
collapsed,  on  moving  the  person's  thorax  vigorously,  we  hear  a  sound  such  as  is 
produced  when  air  and  water  are  shaken  together  in  a  bottle.  This  is  the 
STJCCUSSION'  sound  of  Hippocrates.  Much  more  rarely,  this  sound  is  heard  under 
similar  conditions  in  large  pulmonary  cavities. 

(5.)  When  the  two  apposed  surfaces  of  the  pleura  are  inflamed,  have  become 
soft,  and  are  covered  with  exudation,  they  move  over  each  other  during 
respiration,  and  in  doing  so,  give  rise  to  friction  sounds,  which  can  be  felt  (often 
by  the  patient  himself),  and  can  also  be  heard.  The  sound  is  comparable  to  the 
sound  produced  by  bending  new  leather. 

(6.)  When  we  speak  or  sing  in  a  loud  tone,  the  walls  of  the  chest  vibrate 
(pectoral  rREMiTUS),  because  the  vibration  of  the  vocal  cords  is  propagated 
throughout  the  entire  bronchial  ramifications.  The  vibration  is,  of  course, 
greatest  near  the  trachea  and  large  bronchi.  If  there  be  much  exudation  or  air  in 
the  pleura,  or  great  accumulation  of  mucus  in  the  bronchi,  the  pectoral  fremitus 
is  diminished  or  altogether  absent. 

All  conditions  which  cause  bronchial  breathing  increase  the  pectoral  fremitus. 
Under  normal  circumstances,  therefore,  it  is  louder  where  bronchial  breathing 
is  heard  normally.  The  ear  hears  an  intensified  sound,  which  is  called  broncho- 
phony. If  through  efi"usion  into  the  pleura  or  inflammatory  processes  in  the  lung- 
tissue  the  bronchi  are  pressed  flat,  a  peculiar  bleating  sound  (^GOPHONy)  may  be 
teard, 


PRESSURE   IN   THE   AIR-PASSAGES   DURING  RESPIRATION.        247 

118.  Pressure  in  the  Air-Passages  During 
Respiration. 

Normal  Eespiration. — If  a  manometer  he  tied  into  the  trachea  of  an 
animal,  so  that  the  respiration  goes  on  completely  undisturbed,  during 
every  inspiration  there  is  a  negative  pressure  ( —  3  mm.  Hg.)  and  dur- 
ing expiration  a  positive  pressure  (Bonders).  Donders  placed  the 
U-shaped  manometer  tube  in  one  nostril,  closed  his  mouth,  leaving 
the  other  nostril  open,  and  respired  quietly.  During  every  quiet 
inspiration,  the  mercury  showed  a  negative  jiressure  of  1  mm.,  and 
during  expiration  a  positive  pressure  of  2-3  mm.  (Hg.) 

Forced  Respiration. — As  soon  as  the  air  was  inspired  or  expired 
with  greater  force,  the  variations  in  pressure  became  very  much  greater, 
e.g.,  during  speaking,  singing,  and  coughing.  The  inspiratory  pressure 
was=— -STmm.  (36-74),the  greatest  expiratory  pressure +  87  (82-100) 
mm.  Hg.  (Donders).  The  pressure  of  forced  expiration  therefore,  is  30 
mm.  greater  than  the  inspiratory  pressure. 

Resistance  to  Inspiration. — Notwithstanding  this,  we  must  not  con- 
clude that  the  expiratory  muscles  act  more  powerfully  than  the  inspira- 
tory; for  during  inspiration,  a  variety  of  resistances  has  to  be  overcome, 
so  that  after  these  have  been  met,  there  is  only  a  residue  of  the 
force  for  the  aspiration  of  the  mercury.  The  resistances  to  be  overcome 
by  the  inspiratory  muscles  are: — (1.)  The  elastic  tension  of  the  lungs, 
which  during  the  deepest  expirations  =  6  mm. ;  during  the  deepest  in- 
spirations =  30  mm.  Hg.  (§  107).  (2.)  The  raising  of  the  weight  of  the 
chest.  (3.)  The  elastic  torsion  of  the  costal  cartilages.  (4.)  The  depression 
of  the  abdominal  contents,  and  the  elastic  distension  of  the  abdominal 
walls.  All  these  not  inconsiderable  resistances,  which  the  inspiratory 
muscles  have  to  overcome,  act  during  expiration,  and  aid  the  expiratory 
muscles.  The  forces  concerned  in  inspiration  are  decidedly  much  greater 
than  those  of  expiration. 

As  the  lungs  ivithin  the  chest,  in  virtue  of  their  elasticity,  con- 
tinually strive  to  collapse,  necessarily  they  must  cause  a  negative 
pressure  within  the  chest.  This  amounts  in  dogs  during  inspiration, 
to  7"1  to  7 "5  mm.  Hg.,  and  during  expiration  to  4  mm.  Hg.  (Heynsius). 
The  analogous  values  for  man  have  been  estimated  at  4'5  mm.  Hg.  and 
3  mm,  Hg.,  by  Hutchinson. 

Even  the  greatest  inspiratory  or  expiratory  pressure  is  always  much  less  than  the 
blood-pressure  in  the  large  arteries;  but  if  the  pressure  be  calculated  upon  the 
entire  respiratory  surface  of  the  thorax,  very  considerable  results  are  obtained. 

Effects  of  the  first  Respiration  on  the  Thorax.— Until  birth,  the  airless 

lungs  are  completely  collapsed  (atelectic)  within  the  chest,  and  fill  it,  so  that  on 
opening  the  chest  in  a  dead  foetus,  pneumo-thorax  does  not  occur  (Bernstein). 


248  NASAL   BREATHING. 

Supposing,  however,  respiration  to  have  been  fully  established  after  birth,  and 
air  to  have  freely  entered  the  lungs,  if  a  manometer  be  placed  in  connection  with 
the  trachea  and  the  chest  be  opened,  the  manometer  will  register  a  pressure  of 
6  mm.  Hg.,  due  to  the  collapse  of  the  elastic  lungs.  Bernstein  supposes  that  the 
thorax  assumes  a  new  permanent  form,  due  to  the  first  respiratory  distension;  it 
is  as  if,  owiac  to  the  respiratory  elevation  of  the  ribs,  the  thorax  had  become 
permanently  too  large  for  the  lungs,  which  are,  therefore,  kept  permanently 
distended,  but  collapse  as  soon  as  air  passes  into  the  pleura.  When  a  lung  has 
once  been  filled  with  air,  it  cannot  be  emptied  by  pressure  from  without,  as  the 
small  bronchi  are  compressed  before  the  air  can  pass  out  of  the  alveoli.  The 
expiratory  muscles  cannot  possibly  expel  all  the  air  from  the  lungs,  while  the 
inspiratory  muscular  force  is  sufficient  to  distend  the  lungs  beyond  their  elastic 
equilibrium.  Inspiration  distends  the  lungs,  increasing  their  elastic  tension,  while 
expiration  diminishes  the  tension  without  abolishing  it. 

119.  Appendix  to  Respiration. 

Nasal  Breathing. — During  quiet  respiration,  we  usually  breathe — 
or  ought  to  breathe — through  the  nostrils,  the  mouth  being  closed. 
The  current  of  air  passes  through  the  pharyngo-nasal  cavity — so  that 
in  its  course  during  inspiration,  it  is  (1)  warmed  and  rendered  moist,  and 
thus  irritation  of  the  mucous  membrane  of  the  air-passages  by  the  cold 
air  is  prevented ;  (2)  small  particles  of  soot,  or  other  foreign  substances 
in  the  air,  adhere  to,  and  become  embedded  in  the  mucus  covering  the 
somewhat  tortuous  walls  of  the  respiratory  passages,  and  are  carried 
outwards  by  the  agency  of  the  ciliated  epithelium  of  the  respiratory 
passages ;  (3)  disagreeable  odours  and  certain  impurities  are  detected  by 
the  sense  of  smell. 

If  a  lung  be  inflated,  air  constantly  passes  through  the  walls  of  the  alveoli  and 
trachea.  This  also  occurs  during  violent  expiratory  efforts  (cutaneous  emphysema 
in  whooping-cough),  so  that  pneumo-thorax  may  occur  (J.  R.  Ewald  and 
Roberts). 

Pulmonary  (Edema,  or  the  exudation  of  lymph  or  serum  into  the  pulmonary 
alveoli,  occurs: — (1)  When  there  is  very  great  resistance  to  the  blood-stream  in 
the  aorta  or  its  branches,  e.g.,  by  ligaturing  all  the  arteries  going  to  the  head 
(Sig.  Mayer),  or  the  arch  of  the  aorta,  so  that  only  one  carotid  remains  pervious 
(Welch).  (2)  When  the  pulmonary  veins  are  occluded.  (3)  When  the  left 
ventricle,  owing  to  mechanical  injury,  ceases  to  beat,  while  the  right  ventricle 
goes  on  contracting  (p.  75).  These  conditions  produce  at  the  same  time  anaemia 
of  the  vaso-motor  centre,  which  results  in  stimulation  of  that  centre,  and  conse- 
quent contraction  of  all  the  small  arteries.  Thus,  the  blood-stream  through  the 
veins  to  the  right  heart  is  favoured,  and  this  in  its  turn  favours  the  production  of 
cedema  of  the  lungs. 

120.  Peculiarly  Modified  Respiratory  Movements. 

(1.)  Coughing. — Consists  in  a  sudden  violent  expiratory  explosion  after  a 
previous  deep  inspiration  and  closure  of  the  glottis,  whereby  the  glottis  is  forced 
open  and  any  substance,  fluid,  gaseous  or  solid,  in  contact  with  the  respiratory 
wucoua  inemibrane  is  violently  ejected  through  the  open  mouth.    It  is  produced 


PECULIARLY   MODIFIED   RESPIRATORY   MOVEMENTS.  249 

voluntarily  or  reflexly;  in  the  latter  case,  it  can  be  controlled  by  the  will  only  to 
a  limited  extent. 

[Causes. — A  cough  may  be  discharged  rrjlexhj  from  a  large  number  of  surfaces. 
— (1)  A  draught  of  cold  air  striking  the  skm,  especially  of  the  upper  part  of  the 
body.  (2)  More  frequently  it  is  discharged  from  the  respiratory  mucous  mem- 
brane, especially  of  the  larynx,  the  sensory  branches  of  the  vagus  and  the  superior 
laryngeal  nerve  being  the  afFei-ent  nerves.  (3)  Sometimes  an  offending  body,  such 
as  a  pea  in  the  external  auditory  meatus  gives  rise  to  coughing,  the  afferent  nerve 
being  the  auricular  branch  of  the  vagus.  (4)  There  seems  to  be  no  doubt  that 
there  may  be  a  "gastric  cough,"  especially  in  cases  of  indigestion,  produced  by 
stimulation  of  the  gastric  branches  of  the  vagus.] 

(2.)  Hawking,  or  clearing  the  throat. — An  expiratory  current  is  forced  in  a 
continuous  stream  through  the  narrow  space  between  the  root  of  the  tongue  and 
the  depressed  soft  palate,  in  order  to  assist  in  the  removal  of  foreign  bodies. 
When  the  act  is  carried  out  periodically  the  closed  glottis  is  suddenly  forced  open, 
and  it  is  comparable  to  a  voluntary  gentle  cough.  This  act  can  only  be  produced 
voluntarily. 

(3.)  Sneezing  consists  in  a  sudden  violent  expiratory  blast  through  the  nose, 
for  the  removal  of  mucus  or  foreign  bodies  (the  mouth  being  rarely  open)  after  a 
simple  or  repeated  spasm-like  inspiration— the  glottis  remaining  open.  It  is 
usually  caused  reflexly  by  stimulation  of  sensory  nerve-fibres  of  the  nose  [nasal 
branch  of  the  fifth  nerve],  or  by  sudden  exposure  to  a  bright  light  (Cassius 
Felix,  A.D.  97)  [the  afferent  nerve  is  the  optic].  This  reflex  act  may  be  interfered 
with  to  a  certain  extent,  or  even  prevented,  by  stimulation  of  sensorj'  nerves, 
firmly  compressing  the  nose  where  the  nasal  nerve  issues.  The  continued  use  of 
sternutatories,  as  in  persons  who  take  snufF,  dulls  the  sensory  nerves,  so  that  they 
no  longer  act  when  stimulated  reflexly. 

(4.)  Snoring  occurs  during  respiration  through  the  open  mouth,  whereby  the 
inspiratory  and  expiratory  stream  of  air  throws  the  uvula  and  soft  palate  into 
vibration.  It  is  involuntary,  and  usually  occurs  during  sleep,  but  it  may  be 
produced  voluntarily. 

(5.)  Gargling  consists  in  the  slow  passage  of  the  expiratory  air-current  in  the 
form  of  bubbles  through  a  fluid  lying  between  the  tongue  and  the  soft  palate, 
when  the  head  is  held  backwards.     It  is  a  voluntary  act. 

(6.)  Crying,  caused  by  emotional  conditions,  consists  in  short,  deep 
inspirations,  long  expirations  with  the  glottis  narrowed,  relaxed  facial  and  jaw 
muscles,  secretion  of  tears,  often  combined  with  plaintive  inarticulate  expressions. 
When  crying  is  long  continued,  sudden  and  spasmodic  involuntary  contractions 
of  the  diaphragm  occur,  which  cause  the  inspiratory  sounds  in  the  pharynx  and 
larynx  known  as  sobbing.     This  is  an  involuntary  act. 

(7.)  Sighing  is  a  prolonged  inspiration,  usually  combined  with  a  plaintive 
sound  often  caused  involuntarily,  owing  to  painful  or  unpleasant  recollections. 

(8.)  Laughing  is  due  to  short,  rapid  expiratory  blasts  through  the  tense  vocal 
cords  which  cause  a  clear  tone,  and  there  are  characteristic  inarticulate  sounds  in 
the  lar3mx,  with  vibrations  of  the  soft  palate.  The  mouth  is  usually  open,  and 
the  countenance  has  a  characteristic  expression,  owing  to  the  action  of  the  M. 
zygomaticus  major.  It  is  usually  involuntary,  and  can  only  be  suppressed,  to  a 
certain  degree,  by  the  will  (by  forcibly  closing  the  mouth  and  stopping  respiration). 

(9.)  Yawning  is  a  prolonged,  deep  inspiration  occurring  after  successive 
attempts  at  numerous  inspirations — the  mouth,  fauces,  and  glottis  being  wide 
open ;  expiration  shorter — both  acts  often  accompanied  by  prolonged  character- 
istic sounds.  It  is  quite  involuntary,  and  is  usually  excited  by  drowsiness  or 
ennui. 

[(10.)  Hiccough  is  due  to  a  spasmodic  involuntary  contraction  of  the  diaphragm, 
causing  an  inspiration,  which  is  arrested  by  the  sudden  closure  of  the  glottis,  so 


250  CHEMISTRY  OF  RESPIRATION. 

that  a  characteristic  sound  is  emitted.  Not  unfrequently  it  is  due  to  irritation  of 
the  gastric  mucous  membrane,  and  sometimes  it  is  a  very  troublesome  symptom  in 
uraemic  poisoning.] 


Cliemistry  of  Eespiration. 


121.  duantitative  Estimation  of  Carbonic  Acid, 
Oxygen,  and  Watery  Vapour. 

1.  Estimation  of  002' — !•  The  volume  of  CO2  is  estimated  by  means  of  the 
anthracometer  (Fig.  110,  II)  of  Vierordt.  The  volume  of  gas  is  collected  in  a  gradu- 
ated tube,  r  r,  provided  with  a  bulb  at  one  end  (previously  filled  with  water  and 
carefully  calibrated,  i.e.,  the  exact  amount  which  each  part  of  the  tube  contains  is 
accurately  measured),  and  the  tube  is  closed.  The  lower  end  has  a  stop-cock,  Ti, 
and  to  this  is  screwed  a  flask,  n,  completely  filled  with  a  solution  of  caustic  potash; 
the  stop-cock  is  then  opened,  the  potash  solution  is  allowed  to  ascend  into  the 
tube,  which  is  moved  about  until  all  the  CO2  unites  with  the  potash  to  form 
potassium  carbonate.  Hold  the  tube  vertically  and  allow  the  potash  to  run 
back  into  the  flask,  close  the  stop-cock,  and  remove  the  bottle  with  the  potash.  Place 
the  stop-cock  under  water,  open  it  and  allow  the  water  to  ascend  in  the  tube,  when 
the  space  in  the  tube  occupied  by  the  fluid  indicates  the  volume  of  CO2  which 
is  combined  with  the  potash. 

2.  By  weight. — A  large  quantity  of  the  mixture  of  gases  which  has  to  be  investi- 
gated is  made  to  pass  through  a  Liebig's  bulb  filled  with  caustic  potash.  The 
potash  apparatus  having  been  carefully  weighed  beforehand,  the  increase  of  weight 
indicates  the  amount  of  CO2  which  has  been  taken  up  by  the  potash  from  the  air 
passed  through  it. 

3.  By  Titration. — A  large  volume  of  the  air  to  be  investigated  is  conducted 
through  a  known  volume  of  a  solution  of  barium  hydrate.  The  CO2  unites  with 
the  barium  and  forms  barium  carbonate.  The  fluid  is  neutralised  with  a  standard 
solution  of  oxalic  acid,  and  the  more  barium  that  has  united  with  the  CO2  the 
smaller  will  be  the  amount  of  oxalic  acid  used,  and  vice  vers^. 

II.  Estimation  of  Oxygen. — According  to  volume — (a)  By  the  union  of  the 
O  with  potassium  pyrogallate.  The  same  procedure  is  adopted  as  for  the  estima- 
tion of  CO2,  only  the  flask,  n,  is  filled  with  the  pyrogallate  solution  instead  of 
potash.     (&)  By  exposure  in  an  eudiometer  (see  Blood  gases,  p.  55). 

III.  Estimation  of  Watery  Vapour.— The  air  to  be  investigated  is  passed 
through  a  bulb  containing  concentrated  sulphuric  acid  or  through  a  tube  filled  with 
pieces  of  calcium  chloride.  The  amount  of  water  is  directly  indicated  by  'the 
increase  of  weight. 

122.  Methods  of  Investigation. 

I.  Collecting  the  Expired  Air.— I.  The  air  expired  may  be  collected  in  the  cylinder 
of  the  spirometer  (§  108)  which  is  suspended  in  concentrated  salt  solution  to 
avoid  the  absorption  of  CO2. 


QUANTITATIVE  ESTIMATION   OF  THE  RESPIllED  GASES. 


251 


The  apparatus  of  Andral  and  Gavarret  is  thus  used :— The  operator  breathed 
several  times  into  a  capacious  cylinder  (Fig.  110).  A  mouth-piece  (M)  was  placed 
air-tight  over  the  mouth  while  the  nostrils  were  closed.  The  direction  of  the 
respiratory  current  was  regulated  by  two  so-called  "  Miiller's  valves  "  (mercurial), 
(a  and  b).  With  every  inspiration  the  bottle  or  valve,  a  (filled  below  with  Hg.  and 
hermetically  closed  above)  permits  the  air  inspired  to  pass  to  the  lungs— during 
every  expiration,  the  expired  air  can  pass  only  through  b  to  the  collecting  cylinder  C. 

2.  If  the  gases  given  off  by  the  skin  are  to  be  collected,  a  limb,  or  whatever  part 


f3       0 


® 


u 


a 


Fig.  110. 


I.  Apparatus  of  Andral  and  Gavarret  for  collecting  the  expired  air— C,  large 
cylinder  to  collect  the  air  expired;  P,  weight  to  balance  cylinder;  a,  b,  two 
Miiller's  valves;  M,  mouth-piece.     II.  Anthracometer  of  Vierordt. 


Fig.  111. 
Respiratory  Apparatus  of  Scharling— cZ,  bulb  containing  caustic  potash  to  absorb 
CO2  from  in-going  air;  A,  box  for  man  or  animal  experimented  on;  e  and  g, 
tubes  containing  sulphuric  acid  to  absorb  watery  vapour;  /,  potash  bulb  to 
absorb  CO2  given  off;  C,  vessel  filled  with  water  to  aspirate  air  through  the 
foregoing  system;  h,  stop-cock. 


252 


REGNAULT  AND   REISET  S  APPARATUS. 


is  to  be  investigated,  is  secured  in  a  closed  vessel,  and  the  gases  so  obtained  are 
analysed. 

TT.  The  most  important  apparatus  for  this  purpose  are  those  of— (a.)  Scharling 
(Fig.  Ill),  which  consists  of  a  closed  box,  A,  of  sufficient  size  to  contain  a  man. 
It  has  two  openings — an  entrance  opening,  z,  and  an  exit,  b.  The  latter  is  con- 
nected with  an  aspirator,  C,  a  large  barrel  filled  with  water.  When  the  stop-cock, 
h,  is  opened  and  the  water  flows  out  of  the  barrel,  fresh  air  will  rush  in  continu- 
ously into  the  box,  A,  and  the  air  mixed  Avith  the  expired  gases  will  be  drawn 
towards  C.  A  Liebig's  bulb,  d,  filled  with  caustic  potash,  is  connected  with  the 
entrance  tube,  z,  through  which  the  in-going  air  must  pass,  whereby  it  is  com- 
pletely deprived  of  CO2,  so  that  the  person  experimented  on  is  supplied  with  air 
free  from  CO2.  The  air  passing  out  by  the  exit  tube,  b,  has  to  pass  first  through 
e,  where  it  gives  up  its  watery  vapour  to  sulphuric  acid,  whereby  the  amount  of 
watery  vapour  is  estimated  by  the  increase  of  the  weight  of  the  apparatus,  e. 
Afterwards  the  air  passes  through  a  bulb,  /,  containing  caustic  potash,  which 
absorbs  all  the  CO2,  while  the  tube,  g,  filled  with  sulphuric  acid,  absorbs  any 
watery  vapour  that  may  have  come  from  /.  The  increase  of  weight  of  /  and  g 
indicate  the  amount  of  COg.  The  total  volume  of  air  used  is  known  from  the 
capacity  of  C. 

(6.)  Regnault  and  Reiset's  Apparatus  is  more  complicated,  and  is  used 
when  it  is  necessary  to  keep  animals  for  some  time  under  observation  in  a  bell-jar. 
It  consists  (Fig.  112)  of  a  globe,  R,  in  which  is  placed  the  dog  to  be  experimented 
on.  Around  this  is  placed  a  cylinder,  g  g  (provided  with  a  thermometer,  t)  which 
maybe  used  for  calorimetric  experiments.  A  tube,  c,  leads  into  the  globe,  R; 
through  this  tube  passes  a  known  quantity  of  pure  oxygen  (Fig.  112,  0).    To  absorb 


Scheme  of  the  Respiration  Apparatus  of  Regnault  and  Reiset— R,  globe  for 
animal;  g  g,  outer  casing  for  R,  provided  with  a  thermometer,  t;  d  and  e, 
exit  tubes  to  movable  potash  bulbs,  KOH  and  Koh;  0,  in-gomg  oxygen;  CO2, 
vessel  to  absorb  any  carbonic  acid;  CaClg,  apparatus  for  estimating  the 
amount  of  0  supplied;  /,  manometer. 


V.  PEtTfiNKOFER  S   RESPtRATtON  APPARATUS. 


25j 


any  trace  of  CO2,  a  vessel  containing  potash  (Fig.  112,  CO2)  is  placed  in  the  course 
of  the  tube.  The  vessel  for  measuring  the  O  is  emptied  towards  R,  through  a 
solution  of  calcium  chloride  from  a  large  pan  (Ca  CI2)  provided  with  large  flasks. 
Two  tubes,  d  and  e,  lead  from  R,  and  are  united  by  caoutchouc  tubes  with  the 
potash  bulbs  (KOH,  Ko/t),  which  can  be  raised  or  depressed  alternately  by  means 
of  the  beam,  W.  In  this  way  they  aspirate  alternately  the  air  from  R,  and  the 
caustic  potash  absorbs  the  CO2.  The  increase  of  weight  of  these  flasks  after  the 
experiment  indicates  the  amount  of  CO2  expired.  The  manometer,  /,  shows 
whether  there  is  a  difference  of  the  pressure  outside  and  inside  the  globe,  R. 

(c.)  V.  Pettenkofer  has  invented  the  most  complete  apparatus  (Fig.  113).  It 
consists  of  a  chamber,  Z,  with  metallic  walls,  and  provided  with  a  door  and  a 
window.  At  a  is  an  opening  for  the  admission  of  air,  while  a  large  double  suction- 
pump,  P  Pi  (driven  by  means  of  a  steam-engine)  continually  renews  the  air  within 
the  chamber.  The  air  passes  into  a  vessel,  b,  filled  with  pumice-stone  saturated 
with  sulphuric  acid,  in  which  it  is  dried;  it  then  passes  through  a  large  gas-meter, 
c,  which  measures  the  total  amount  of  the  air  passing  through  it. 

After  the  air  is  measured,  it  is  emptied  outwards  by  means  of  the  pump,  P  Pj. 
From  the  chief  exit  tube,  x,  of  the  chamber,  provided  with  a  small  manometer,  q,  a 
narrow  laterally  placed   tube,  ??,  ])asses,  conducting  a  small  secondary  stream, 


Fig.   113. 
Respiration  Apparatus  of  v.  Pettenkofer — Z,  chamber  for  person  experimented  on ; 
X,  exit  tube  with  manometer,  q;  b,  vessel  with  sulphuric  acid;  C,  gas-meter; 
PPi,  pump;  n,  secondary  current,  with,  k,  bulb;  MM],  suction  apparatus; 
w,  gas-meter;  N,  stream  for  investigating  air  before  it  enters  Z. 

which  is  chemically  investigated.  This  current  passes  through  the  suction- 
apparatus,  M  Ml  (constructed  on  the  principle  of  MuUer's  mercurial  valve,  and 
driven  by  a  steam-engine).  Before  reaching  this  apparatus,  the  air  passes  through 
the  bulb,  K,  filled  with  sulphuric  acid,  whose  increase  in  weight  indicates  the 
amount  of  watery  vapour.      After  passing  through  MMi,  it  goes   through   the 


254  COMPOSITION   AND   PROPERTIES   OP  ATMOSPHERIC  AIR. 

tube,  R,  filled  with  baryta  solution,  which  takes  up  the  CO2.  The  quantity  of 
air  which  passes  through  the  accessory  current,  n,  is  measured  by  the  small  gas- 
meter,  M,  from  which  it  passes  outwards.  The  second  accessory  stream,  N,  enables 
us  to  investigate  the  air  before  it  enters  the  chamber,  and  it  is  arranged  in 
exactly  the  same  way  as  n. 

The  increase  of  CO2  and  Hg  O  in  the  accessory  stream,  n  (i.e.,  more  than  inN), 
indicates  the  amount  of  CO2  given  off  by  the  pressure  in  the  chamber,  Z. 

123.  Composition  and  Properties  of  Atmospheric  Air. 


1.  Dry  Air  contains : — 

Gas. 

By  Weight. 

By  Volume. 

0,        .        .         . 

23'015 

20-96 

N,        .        .        . 

76-985 

79-02 

CO,,     .        .         . 

0-03—0-034 

2.  Aqueous  Vapour  is  always  present  in  the  air,  but  it  varies 
greatly  in  amount,  and  generally  increases  with  the  increase  of  the 
temperature  of  the  air.  In  connection  with  the  moisture  of  the  air  we 
distinguish  (a),  the  absolute  moisture,  i.e.,  the  quantity  of  watery  vapour 
which  a  volume  of  air  contains  in  the  form  of  vapour ;  and  (&),  the 
relative  moisture,  i.e.,  the  amount  of  watery  vapour  which  a  volume  of 
air  contains  with  respect  to  its  temperature. 

Experience  shows  that  people  generally  can  breathe  most  comfortably  in  an 
atmosphere  which  is  not  completely  saturated  with  aqueous  vapour  according  to  its 
temperature,  but  is  only  saturated  to  the  extent  of  70  per  cent.  If  the  air  be  too 
dry  it  irritates  the  respiratory  mucous  membrane ;  if  too  moist,  there  is  a  disagree- 
able sensation,  and  if  it  be  too  warm  a  feeling  of  closeness.  Hence,  it  is  important 
to  see  that  the  proper  amount  of  watery  vapour  is  present  in  the  air  of  our  sitting- 
rooms,  bedrooms,  and  hospital  wards. 

The  absolute  amount  of  moisture  varies : — In  towns  during  the  day  it  increases 
with  increase  of  temperature,  and  diminishes  when  the  temperature  falls;  it  also 
varies  with  the  direction  of  the  wind,  season  of  the  year,  height  above  sea-level. 

The  relative  amount  of  moisture  is  greatest  at  sunrise,  least  at  midday ;  small 
on  high  mountains;  greater  in  winter  than  in  summer;  larger  with  a  south  or  a 
west  wind  than  with  a  north  or  an  east  wind. 

The  air  in  midsummer  contaias  absolutely  three  times  as  much  watery  vapour 
as  in  midwinter,  nevertheless  the  air  in  summer  is  relatively  drier  than  the  air  in 
winter. 

3.  The  air  Expands  by  Heat.  Rudberg  found  that  1,000  volumes 
of  air,  at  0°,  expanded  to  1,365  when  heated  to  100°C. 

4.  The  Density  of  the  air  diminishes  with  increase  of  the  height 
above  the  sea-level. 

124.  Composition  of  Expired  Air. 

1.  The  expired  air  contains  more  CO2 — in  normal  respiration  =  4'38 
vols,  per  cent.  (3-3  to  5-5  per  cent.),  so  that  it  contains  nearly  100 
times  more  CO2  than  the  atmospheric  air. 

2.  It  contains  LESS  0  (4-782  vols,  per  cent,  less)  than  the  atmos- 
pheric air,  i.e.,  it  contains  only  16-033  vols,  per  cent,  of  0. 


COMPOSITION    OF   EXPIRED  AIR. 


255 


3.  Respiratory  Quotient. — Hence,  during  respiration,  more  0  is 
taken  into  the  body  from  the  air  than  CO2  is  given  off  (Lavoisier) ;  so 
that  the  volume  of  the  expired  air  is  (yg-  -  ^V)  smaller  than  the  volume 
of  the  air  inspired,  both  being  calculated  as  dry,  at  the  same  tempera- 
ture, and  at  the  same  barometric  pressure.  The  relation  of  the  0 
absorbed  to  the  CO3  given  off,  is  4-38  :  4-782.  This  is  expressed  by 
the  "  respiratory  quotient^' — 

Ca/     4-3M^0-906. 
0   \     4-782/ 

4.  An  excessively  small  quantity  of  N  is  added  to  the  expired  aii' 
(Eegnault  and  Reiset).  Seegen  found  that  all  the  N  taken  in  with  the 
food  did  not  reappear  in  the  excreta  (urine  and  faeces),  and  he  assumed 
that  a  small  part  of  it  was  given  off  by  the  lungs, 

5.  During  ordinary  respiration,  the  expired  air  is  saturated  with  watery 
vapour.  It  is  evident,  therefore,  that  when  the  watery  vapour  in  the 
air  varies,  the  lungs  give  off  different  quantities  of  water  from  the 
body.  The  percentage  of  watery  vapour  falls  during  rapid  respiration 
(Moleschott). 

6.  The  expired  air  is  WARMER  (36-3°C),  that  is,  very  ^ 
near  the  temperature  of  the  body,  and  even  although 
the  temperature  of  the  surrounding  atmosphere  be^very 
variable,  the  temperature  of  the  exj^ired  air  still  remains 
nearly  the  same. 

The  Instrument  (Fig.  114)  was  used  by  Valentin  and  Brunner 
to  determine  the  temperature  of  the  expired  air.  It  consists  of  a 
glass  tube,  A,  A,  with  a  mouth-piece,  B,  and  in  it  is  a  fine 
thermometer,  C.  The  operator  breathes  through  the  nose  and 
expires  slowly  through  the  mouth-piece  into  the  tube. 

Temperature  of  the 
Expired  Air. 

+  29-S°C 
...         .         +36-2-37 
.    '     .         .         +38-1° 

+  38-5° 

7.  The  diminution  of  the  volume  of  the^expired  air 
mentioned  under  (3)  is  far  more  than  compensated  by 
the  warming  which  the  inspired  air  undergoes  in  the 
respiratory  passages,  so  that  the  volume  of  the  expired  air 
is  one-ninth  greater  than  the  air  inspired. 

8.  A  very  small  quantity  of  ajvimonia  is  found  in  the 
expired  air  (Eegnault  and  Eeiset)  =  0'0204  grammes  in 
24  hours  (Losseu) ;  it  is  probably  derived  from  the  blood, 
for  blood  exposed  to  the  air  evolves  ammonia  (Briicke). 

9.  Small  quantities  of  H  and  CH^  are  expired,  both 
being  absorbed  from  the  intestine.  In  herbivora,  Reiset 
found  that  30  litres  of  CH4  were  expired  in  24  hours. 


Temperature  of 
the  Air. 

-6-3°C, 
+  17-19°, 

+41°, 

+  44°, 


250 


DAILY  QUANTITY  OF  GASES  EXCHANGED. 


125.  Daily  Quantity  of  Gases  Exchanged. 

As  under  normal  circumstances  more  0  is  absorbed  than  there  is 
CO2  given  off  (equal  volumes  of  0  and  CO2  contain  equal  quantities  of 
0),  a  part  of  the  O  must  be  used  for  other  oxidation-processes  in  the 
body.  According  to  the  extent  of  these  latter  processes,  the  ratio  of 
the  0  taken  in  to  the  CO2  given  out — 


V  0 


0"906  normally)  must  vary. 


The  amount  of  COg  given  off  may  be  less  than  the  "mean"  above 
stated.  The  quantity  of  COg  alone  is  not  a  reliable  indication  of  the 
entire  exchange  of  gases  during  respiration ;  we  must  estimate  simul- 
taneously the  amount  of  0  absorbed,  and  the  COg  given  off. 


126.  Review  of  Daily  Gaseous  Income  and 
Expenditure. 


Income  in  24  hows. 

Expenditure  in 

24  hours. 

Oxygen— 

Carbonic  Acid- 

744  grnis.  =  516"500c.cmtr.  (Vicrordt). 

goo  grms.  =  455500  c 

.cmtr.  (Vierordt) 

.S6  grms.          i)er  hour         (Scharling) 

32-8 -33-4  grms.     ,, 

(Liebermeister) 

(At    CC    and    mean    barometric 

34  grms.         .          , , 

(Panum) 

pressure. ) 

31-5-33  grms. 

(Ranke). 

Water— 640  grms.     . 

.     (Valentin) 

330    „ 

(Vierordt) 

127,  Conditions  Influencing  the  Gaseous  Exchanges. 

The  formation  of  COg,  in  all  probability,  consists  of  two  distinct 
processes.  First,  compounds  containing  COg  seem  to  be  formed  in 
the  tissues  which  are  oxidation  products  of  substances  containing  carbon. 
The  second  process  consists  in  the  separation  of  this  COg,  which,  how- 
ever, takes  place  without  the  absorption  of  0.  Both  processes  do  not 
always  occur  simultaneously,  and  the  one  process  may  exceed  the  other 
in  extent  (L.  Hermann,  Pfluger). 

According  to  Schmiedeberg,  the  oxidation  in  the  tissues  depends  upon  a 
synthesis  with  the  liberation  of  H2O,  the  blood  supplying  the  necessary  O. 

The  following  affect  these  processes : — 

1.  Age. — Until  the  body  is  fully  developed,  the  CO,  given  off  increases, 
but  it  diminishes  as  the  bodily  energies  decay.  Hence,  in  young  persons 
the  0  absorbed  is  relatively  greater  than  the  COg  given  off ;  at  other 
periods  both  values  are  pretty  constant.     Example  : — 


CONDITIONS   INFLUENCING  THE  EXCRETION   OF   COo. 


257 


Age — j'ears. 

In  24  hours. 

CO2  Gram,  excreted. 
=  Carbon. 

Absorbed  Gram. 

8 

443  Gram.  =  121  Carbon. 

375  Grainmes. 

15 

766       „       =  209 

652 

16 

950      „       =  259 

809 

18-20 

1003      „       =  274 

854 

20-24 

1074      „       =  293 

914 

40-60 

889       „       =  242 

757 

60-80 

810       „       =  221 

689 

The  absolute  amount  of  COg  given  off  is  less  in  children  than  in  adults; 
but  if  the  CO2  given  off  be  calculated  with  reference  to  body-weight, 
then,  weight  for  weight,  a  child  gives  off  twice  as  much  COj  as  an  adult. 

2.  Sex. — Males,  from  the  eighth  year  onwards  to  old  age,  give  off 
about  one-third  more  COo  than  females  (Andral  and  Gavarret).  This 
difference  is  more  marked  at  puberty,  when  the  difference  may  rise  to 
one-half.  After  cessation  of  the  menses,  there  is  an  increase,  and  in  old 
age  the  amount  of  CO,  given  off  diminishes.  Pregnancy  increases  the 
amount,  owing  to  causes  which  are  easily  understood. 

3.  The  Constitution. — As  a  general  rule,  muscular,  energetic  persons 
use  more  0  and  excrete  more  CO2  than  less  active  persons  of  the  same 
weight. 

4.  Alternation  of  Day  and  Night. — The  CO.  given  off  is  diminished 
during  sleep  about  one-fourth  (Scharling).  This  diminution  is  caused 
by  the  constant  heat  of  the  surroundings  (bed),  darkness,  absence  of 
muscular  activity,  and  the  non-taking  of  food  (see  5,  6,  7,  9).  It  does 
not  seem  that  any  0  is  stored  up  during  sleep  (S.  Lewin).  After 
awaking  in  the  morning,  the  respirations  are  more  rapid  and  deeper, 
and  thus  the  amount  of  CO,  given  off  is  increased.  It  decreases  during 
the  forenoon,  until  dinner  at  mid-day  causes  another  increase.  It  falls 
during  the  afternoon,  and  increases  again  after  supper. 

During  hybernation,  when  no  food  is  taken,  and  when  the  respirations 
cease,  or  are  enormously  diminished,  the  respiratory  exchange  of  gases 
is  carried  out  by  diffusion  and  by  the  cardio-pneumatic  movements 
(p.  109).  The  CO2  given  off  falls  to  tt>  the  0  taken  in  to  jV  of  what 
they  are  in  the  waking  condition  (Valentin).  Much  less  CO2  is  given 
off  than  0  taken  in,  so  that  the  body-Aveight  may  increase  through  the 
excess  of  0. 

5.  Temperature  of  the  Surroundings. — Cold-blooded  animals  become 
warmer  when  the  temperature  of  their  environment  is  raised,  and  they 
give  off  more  COo  in  this  condition  than  when  they  are  cooler 
(Spallanzani) — e.g.,  a  frog  with  the  temperature  of  the  surroundings  at 

17 


258  CONDITIONS   INFLUENCING  THE  EXCRETION   OF  COg, 

39°0.  excreted  three  times  as  much  COg  as  when  the  temperature  was 
6°C.  (Moleschott). 

Warm-Uooded  animals  behave  somewhat  differently  when  the  temper- 
ature of  the  surrounding  medium  is  changed.  When  the  temperature 
of  the  animal  is  lowered  thereby,  there  is  a  considerable  decrease  in  the 
amount  of  COg  given  off,  as  in  cold-blooded  animals ;  but  if  the  temper- 
ature of  the  animal  be  increased  (also  in  fever),  the  CO2  is  increased 
(C.  Ludwig  and  Sanders-Ezn).  Exactly  the  reverse  obtains  when  the 
temperature  of  the  surroundings  varies,  and  the  bodily  temperature 
remains  constant.  As  the  cold  of  the  surrounding  medium  increases, 
the  processes  of  oxidation  within  the  body  are  increased  through  some 
as  yet  unknown  reflex  mechanism;  the  number  and  dejDth  of  the 
respirations  increase,  whereby  more  0  is  taken  in  and  more  CO2  is  given 
out  (Lavoisier).  A  man  in  January  uses  3 2 "2  grammes  0  per  hour;  in 
July  only  31  "7  grammes.  In  animals,  with  the  temperature  of  the 
surroundings  at  8°C.,  the  CO2  given  off  was  one-third  greater  than  with 
a  temperature  of  38°C.  When  the  temperature  of  the  air  increases — 
the  body  temperature  remaining  the  same — the  respiratory  activity  and 
the  CO2  given  off  diminish,  while  the  pulse  remains  nearly  constant 
(Vierordt).  On  passing  suddenly  from  a  cold  to  a  warm  medium  the 
amount  of  COg  is  considerably  diminished ;  and  conversely,  on  passing 
from  a  warm  to  a  cold  medium,  the  amount  is  considerably  increased 
(compare  Begulation  of  Temperature). 

6.  Muscular  exercise  causes  a  considerable  increase  in  the  COg  given 
out  (Scharling),  which  may  be  three  times  greater  during  walking  than 
during  rest  (Ed.  Smith).  Ludwig  and  Sczelkow  estimated  the  0  taken 
in  and  the  CO2  given  off  by  a  rabbit  during  rest,  and  when  the  muscles 
of  the  hind  limbs  were  tetanised.  During  tetanus  the  0  and  CO2  were 
increased  considerably,  but  in  tetanised  animals  more  0  was  given 
off  in  the  CO2  expired  than  was  taken  up  simultaneously  during  respira- 
tion. The  passive  animal  absorbed  nearly  twice  as  much  0  as  the 
amount  of  CO2  given  off  (compare  Metabolism  in  Muscle). 

7.  Taking  of  food  causes  constantly  a  not  inconsiderable  increase  in 
the  COg  given  off,  which  depends  upon  the  quantity  taken,  and  the 
increase  generally  occurs  about  an  hour  after  the  chief  meal — dinner 
(Vierordt).  During  inanition,  the  exchange  of  gases  diminishes  con- 
siderably until  death  occurs  (Letellier).  At  first  the  COg  given  off 
diminishes  more  quickly  than  the  0  is  taken  up.  The  quality  of  the  food 
influences  the  COg  given  off  to  this  extent,  that  substances  rich  in  carbon 
(carbohydrates  and  fats)  cause  a  greater  excretion  of  COg  than  substances 
which  contain  less  C  (albumins).  Eegnault  and  Reiset  found  that  a  dog 
gave  off  79  per  cent,  of  the  0  inspired  after  a  flesh  diet,  and  91  per  cent, 
after  a  diet  of  starch.      If  easily  oxidisable  substances  (glycerine  or 


CONDITIONS   INFLUENCING   THE    EXCRETION   OF   CO.,. 


259 


lactate  of  soda),  are  injected  into  the  blood,  the  0  taken  in,  and  the  COg 
given  off,  undergo  a  considerable  increase  (Ludwig  and  Scheremetjewsky). 
Alcohols,  tea,  and  ethereal  oils,  diminish  the  COg  (Prout,  Vierordt). 
[Ed.  Smith  found  that  the  eflfects  produced  by  alcoholic  drinks  varied 
with  the  nature  of  the  spirituous  liquor.  Thus  brandy,  whisky,  and 
gin  diminish  the  amount,  while  pure  alcohol,  rum,  ale,  and  porter  tend 
to  increase  it.] 

8.  The  Number  and  Depth  of  the  Respirations  have  practically  no 
influence  on  the  formation  of  COg,  or  the  oxidation-processes  within  the 
body,  these  being  regulated  by  the  tissues  themselves,  by  some  mechanism 
as  yet  unknown  (Pfliiger).  They  have  a  marked  effect,  however,  upon 
the  removal  of  the  already  formed  CO2  from  the  body.  An  increase  in 
the  number  of  respirations  (their  depth  remaining  the  same),  as  well  as 
an  increase  of  their  depth,  the  number  remaining  the  same,  cause  an 
absolute  increase  in  the  amount  of  CO^  given  off,  which  with  reference 
to  the  total  amount  of  gases  exchanged,  is  relatively  diminished.  The 
following  example  from  Vierordt  illustrates  this  : — 


No.ofResps. 

Vol.  of  Air. 

Amount  of 

per  cent. 

Depth  of 

Amount  of 

per  cent. 

per  mm. 

CO2.       - 

-     CO2. 

Resps. 

CO2. 

CO2. 

12 

6000 

258  c.cmtr. 

=4,3  % 

500 

21  c.cmtr. 

=4-3  7o 

24 

12000 

420 

=3,5  „ 

1000 

36        „ 

=  3-6  „ 

48 

24000 

744 

=  3,1  „ 

1500 

51 

=  3-4  „ 

96 

48000 

1392 

=  2,9  ,, 

2000 
3000 

64        „ 

72        „ 

=  3-2,, 

=  2-4  „ 

9.  Exposure  to  a  blight  light  causes  an  increase  in  the  CO2  given  off  in 
frogs  (Moleschott,  1855);  in  mammals  and  birds  (Selmi  and  Piacentini);  even  in 
frogs  deprived  of  their  lungs  (Fubini) ;  or  in  those  whose  spinal  cord  has  been 
divided  high  up  (Chasanowitz).  The  consumption  of  0  is  increased  at  the  same 
time  (Pfliiger  and  v.  Platen).  The  same  results  occur  in  blind  persons,  although 
to  a  less  degree.  Bluish-violet  light  is  almost  as  active  as  white  light,  while  red 
light  is  less  active  (Moleschott  and  Fubini). 

10.  The  experiments  of  Grehant  on  dogs,  seem  to  show  that  intense  inflamma- 
tion of  the  bronchial  mucous  membrane  influences  the  CO2  given  off. 

11.  Amongst  poisons,  thebaia  increases  the  COg  given  off,  while  morphia, 
codeia,  narcein,  narcotui,  papaverin,  diminish  it  (Fubini). 

128.  Diffusion  of  Gases  within  the  Lungs. 

The  air  within  the  air-vesicles  contains  most  COg  and  least  0,  and  as 
we  pass  from  the  small  to  the  large  bronchi  and  onwards  to  the  trachea, 
the  composition  of  the  air  gradually  approaches  more  closely  to  that  of 
the  atmosphere  (Allan  and  Pepys).  Hence,  if  the  air  expired  be 
collected  in  two  portions,  the  first  half  {i.e.,  the  air  from  the  larger  air- 
passages),  contains  less  COg  (3*7 vols,  per  cent.)  than  the  second  haK 
(5*4  vols,  per  cent.).     This  difference  in  the  percentage  of  gases  gives 


260      EXCHANCrES   OF  GASES   BETWEEN  THE   AIR  AND   THE  BLOOD. 

rise  to  a  diffusion  of  the  gases  witliin  the  air-passages ;  the  COg  must 
diffuse  from  the  air-vesicles  outwards,  and  the  0  from  the  atmosphere 
and  nostrils  inwards  (compare  p.  52).  This  movement  is  aided  by 
the  cardio-pneumatic  movement  (Landois,  p.  109).  In  hybernating 
animals  and  in  persons  apparently  but  not  actually  dead^  the  exchange  of 
gases  within  the  lungs  can  only  occur  in  the  above-mentioned  ways. 

For  ordinary  purposes  this  mechanism  is  insufficient,  and  there  are 
added  the  respiratory  movements  whereby  atmospheric  air  is  introduced 
into  the  larger  air-passages,  from  which  and  into  which  the  diffusion 
currents  of  0  and  COg  pass,  on  account  of  the  difference  of  tension  of 
the  gases. 


129.  Exchange  of  Gases  between  the  Blood  of  the 

Pulmonary  Capillaries  and  the  Air  in 

the  Air- Vesicles. 

This  exchange  of  gases  occurs  almost  exclusively  through  the  agency 
of  chemical  processes  (independent  of  the  diffusion  of  gases). 

Method. — It  is  important  to  ascertain  the  tension  of  the  0  and  CO2  in  the  venous 
blood  of  the  pulmonary  capillaries,  Pfliiger  and  Wolfberg  estimated  the  tension 
by  "  catheterising  the  lungs."  An  elastic  catheter  was  introduced  through  an 
opening  in  the  trachea  of  a  dog  into  the  bronchus  leading  to  the  lowest  lobe  of  the 
left  lung.  An  elastic  sac  was  placed  round  the  catheter,  and  when  the  latter  was 
introduced  into  the  bronchus,  the  sac  around  the  catheter  was  distended  so  as  to 
plug  the  bronchus.  No  air  can  escape  between  the  catheter  and  the  wall  of  the 
bronchus.  The  outer  end  of  the  catheter  was  closed  at  first,  and  the  dog  was 
allowed  to  respire  quietly.  After  four  minutes  the  air  in  the  air-vesicles  was 
completely  in  equilibrium  with  the  blood-gases.  The  air  of  the  lung  was  sucked 
out  of  the  catheter  by  means  of  an  air-pump,  and  afterwards  analysed. 

Thus  we  may  measure  indirectly  the  tension  of  the  0  and  CO2  in 
the  venous  blood  of  the  pulmonary  capillaries.  The  direct  estima- 
tion of  the  gases  in  different  kinds  of  blood  is  made  by  shaking  up  the 
blood  with  another  gas.  The  gases  so  removed  indicate  directly  the 
proportion  of  blood-gases. 

The  following  tabular  arrangement  indicates  the  tension  and  per- 
centage of  0  and  COg  in  arterial  and  venous  blood,  in  the  atmosphere, 
and  in  the  air  of  the  alveoli : — 


I. 
0-Tension  in  arterial  blood=:29-6  mm. 
Hg.  (corresponding  to  a  mixture  con- 
taining 3'9  vol.  per  cent,  of  0). 

II. 

COg-Tension  in  arterial  blood  =  21  mm. 
Hg.  (corresponding  to  2 '8  vol.  per 
cent.) 


III. 

0-Tension  in  venous  blood =22  mm.  Hg, 

(corresponding  to  2'9  vol.  per  cent.) 


IV. 

CO^-Tensioti  in  venous  blood =41  mm. 
Hg.  (corresponding  to  5 '4  vol.  per 
cent.) 


ABSORPTION    OF   OXYGEN    IX   THE   LUNGS. 


2G1 


0-Tension  ia  the  aii-  of  the  alveoli  of  the 
catheterised  lung  =  27 '44  mm.  Hg. 
(corresponding  to  3 "6  vol.  per  cent.) 

VI. 

CO2 -Tension  iu  the  air  of  the  alveoli  of 
the  catheterised  lung  =  27  mm,  Hg. 
(corresponding  to  3 "56  vol.  per  cent.) 


VII. 
0-Tension  in  the  atmosphere  =  158  mm. 
Hg.  (corresponding  to  20 'S  vol.  per 
cent.) 

VIU. 

C02-Tension  in  the  atmosphere  =  0'3S 
mm.  Hg.  (corresponding  to  0  "03-0  05 
vol.  per  cent. ) 


When  we  compare  the  tension  of  the  0  in  the  air  (VII.  =  158  mm. 
Hg.)  with  the  tension  of  the  0  in  venous  blood  (III.  =  22  mm.  Hg.,  or 
V.  =  27*44  mm.  Hg.),  we  might  be  inclined  to  assume  that  the  passage 
of  the  0  from  the  air  of  the  air-vesicles  into  the  blood  was  due  solely 
to  diffusion  of  the  gases ;  and  similarly,  we  might  assume  that  the 
CO2  of  the  venous  blood  (IV.  or  VI.)  diffused  into  the  air-vesicles, 
because  the  tension  of  the  COo  in  the  air  is  much  less  (VIII.)  There 
are  a  number  of  facts,  however,  which  prove  that  the  exchange  of  the 
gases  in  the  lungs  is  chiefly  due  to  chemical  forces. 

Absorption  of  0. — With  regard  to  the  absorption  of  0  from  the  air 
in  the  alveoli  into  the  venous  blood  of  the  lung  capillaries,  whereby 
the  blood  is  arterialised,  it  is  proved  that  this  is  a  chemical  p-ocess.  The 
gas-free  (reduced)  hremoglobin  takes  up  0  to  form  oxyhsemoglobin  (§  1 .5, 
1 ).  That  this  absorption  has  nothing  to  do  directly  with  the  diflfusion 
of  gases,  but  is  due  to  a  chemical  combination  of  the  atomic  compounds, 
is  shown  by  the  fact,  that,  when  pure  0  is  respired,  the  blood  does  not 
take  up  more  0  than  when  atmospheric  air  is  respired  ;  further,  that 
animals  made  to  breathe  in  a  limited  closed  space  can  absorb  almost  aU 
the  0 — even  to  traces — into  their  blood  before  suffocation  occurs.  Of 
course  if  the  absorption  of  0  were  due  to  diffusion,  in  the  former  case 
more  0  would  be  absorbed,  while  in  the  latter  case  the  absorption  of  0 
could  not  possibly  occur  to  such  an  extent  as  it  does. 

The  law  of  diffusion  comes  into  play  in  connection  with  the  absorp- 
tion of  0  to  this  extent,  viz.,  that  the  0  diffuses  from  the  air-cells  of 
the  lung  into  the  blood-plasma,  where  it  reaches  the  blood-corpuscles 
suspended  in  the  plasma.  The  hfBmoglobin  of  the  blood-corpuscles 
forms  at  once  a  chemical  compound  (oxyhaemoglobin)  with  the  0. 

Even  in  very  rarijied  air,  such  as  is  met  with  in  the  upper  regions  of  the 
atmosphere  during  a  balloon  ascent,  the  absorption  of  0  still  remains  independent 
of  the  partial  pressure  (Loth.  Mayer,  Fernet).  But  a  much  longer  time  is  required 
for  this  process  at  the  oixlinaiy  temperature  of  the  body,  so  that  in  rarified  au",  the 
absorption  of  0  is  greatly  delayed,  but  it  is  not  diminished.  This  is  the  cause  of 
death  in  aeronauts  who  have  ascended  so  high  that  the  atmospheric  pressure  is 
diminished  to  one-third  (Setschenow). 

Excretion  of  COo. — With  regard  to  the  excretion  of  CO2  from  the 
blood,  we  must  remember  that  the  CO2  in  the  blood  exists  in  two  con- 


262  EXCRETION   OF   CARBONIC  ACID  BY  THE  LUNGS. 

ditions.  Part  of  the  COg  forms  a  loose  or  feeble  chemical  compound, 
■while  another  portion  is  more  firmly  combined.  The  former  is  obtained 
by  those  means  which  remove  gases  from  fluids  containing  them 
in  a  state  of  absorption,  so  that  in  removing  the  COg  from  the  blood  it 
is  difficult  to  determine  whether  the  CO2,  so  removed,  obeyed  the  law 
of  diffusion,  or  if  it  was  expelled  by  chemical  means. 

Although  it  is  convenient  to  represent  the  excretion  of  CO2  from  the 
blood  into  the  air-vesicles  of  the  lung,  as  due  to  equilibration  of  the 
tension  of  the  CO2  on  opposite  sides  of  the  alveolar  membrane,  i.e.,  to 
diffusion — nevertheless,  chemical  pvcesses  play  an  important  part  in  this 
act.  The  absorption  of  O  by  the  coloured  corpuscles  acts,  at  the  same 
time,  in  expelling  COj.  This  is  proved  by  the  fact  that  the  expulsion 
of  CO2  from  the  blood  takes  place  more  readily  when  0  is  simultaneously 
admitted  (Ludwig  and  Holmgren). 

The  free  supply  of  0  not  only  favours  the  removal  of  the  CO2,  which 
is  loosely  combined,  but  it  also  favours  the  expulsion  of  that  portion  of 
the  CO2  which  is  more  firmly  combined,  and  which  can  only  be 
expelled  by  the  addition  of  acids  to  the  blood  (Ludwig,  Schoffer  and 
Sczelkow).  That  the  oxygenated  blood-corpuscles  (i.e.,  their  oxyhsemo- 
globin)  are  concerned  in  the  removal  of  CO2,  is  proved  by  the  fact  that 
CO2  is  more  easily  removed  from  serum  which  contains  oxygenated 
blood-corpuscles  than  from  serum  charged  with  0. 

[The  following  scheme  may  serve  to  illustrate  the  extent  to  which 
diffusion  comes  into  play.  The  O  must  pass  through  the  alveolar 
membrane,  A  B — including  the  alveolar  epithelium  and  the  wall  of  the 
capillaries — as  well  as  the  blood-plasma,  to  reach  the  haemoglobin  of 
the  blood-corpuscles.  Similarly,  the  COg  must  leave  the  salts  of  the 
plasma  with  which  it  is  in  combination,  and  diffuse  in  the  opposite 
direction,  through  the  wall  of  the  capillaries,  the  alveolar  membrane 
and  epithelium,  to  reach    the    air-vesicles.     Let   AB  represent  the 

(     CO2 O 

Partial  pressure  of  air  in         \ 

alveoli  of  lung.  )       27 27-44 

--H ^' 

Tension  of  gases  in  venous      )       41  22 

blood  of  lung.  ) 

I     CO2 O 

alveolar  membrane;  on  the  one  side  of  it  is  represented  the  partial 
pressure  of  the  COg  and  0  in  the  air-vesicles;  and  on  the  other,  the 
partial  pressure  of  the  COg  and  0  in  the  venous  blood  entering  the 
lung.     The  arrows  indicate  the  direction  of  diffusion.] 

Theories. — Various  theories  have  been  proposed  to  account  for  the  expulsion  of 
the  CO2  from  its  state  of  chemical  combination  in  the  blood  due  to  the  action  of 
the  oxygenated  blood-corpuscles,     (a.)  It  is  possible  that  the  CO2  in  the  blood- 


DISSOCIATION   OF  GASES.  263 

corpuscles  (perhaps  united  with  paraglobulin  ? — Setschenow)  is  expelled  by  the  O 
taken  up ;  (6.)  the  acid  reaction  of  the  hsemoglobin  (Preyer)  may  act  so  as  to  expel 
the  CO2  out  of  the  corpuscles  and  the  plasma  ;  (c.)  by  the  absorption  of  O  volatile 
fatty  acids  may  be  formed  from  the  hsemoglobin  (Hoppe-Seyler).  These  acids 
may  act  so  as  to  expel  the  COg. 

Nature  of  the  Process. — The  exchange  of  gases  between  the  blood 
and  the  air  in  the  lungs  has  been  represented  by  Bonders  as  due  to  a 
process  of  dissociation. 

130.  Dissociation  of  Gases. 

Many  gases  form  true  cJiemical  compounds  with  other  bodies  (i.e., 
they  combine  according  to  their  equivalents),  when  the  contact  of  these 
bodies  is  effected  under  conditions  such  that  the  partial  pressure  of 
the  gases  is  high.  The  chemical  compound  formed  under  these  con- 
ditions is  broken  up,  whenever  the  partial  pressure  is  diminished,  or 
when  it  reaches  a  certain  minimum  level,  which  varies  with  the  nature 
of  the  bodies  forming  the  compound.  Thus,  by  increasing  and  dimin- 
ishing the  partial  pressure  alternately,  a  chemical  compound  of  the  gas 
may  be  formed  and  again  broken  up.  This  process  is  called  Dissocia- 
tion of  the  gases.  The  minimal  partial  pressure  is  constant  for  each 
of  the  different  substances  and  gases,  but  temperature,  as  in  the  case  of 
the  absorption  of  gases,  has  a  great  effect  on  the  partial  pressure ;  with 
increase  of  temperature  the  partial  pressure,  under  which  dissociation 
occurs,  diminishes. 

As  an  example  of  the  dissociation  of  a  gas,  take  the  case  of  calcium  carbonate. 
When  it  is  heated  in  the  air  to  440°C,  CO2  is  given  off  from  its  state  of  chemical 
combination,  but  is  taken  up  again  and  a  chemical  compound  formed,  which  is 
changed  into  clialk  when  it  cools. 

Dissociation  in  the  Blood. — The  chemical  combinations  containing 
CO2  and  those  containing  O  within  the  blood-stream  behave  in  a  similar 
manner — viz.,  the  salts  of  the  plasma,  which  are  combined  with  COg,  and 
the  oxyhsemoglobin.  If  these  compounds  of  0  and  CO2  are  placed  under 
conditions  where  the  partial  pressure  of  these  gases  is  very  low — i.e., 
in  a  medium  containing  a  very  small  amount  of  these  gases,  the  com- 
pounds are  dissociated — i.e.,  they  give  off  CO2  or  0.  If  after  being 
dissociated,  they  are  placed  under  conditions  where,  owing  to  the  large 
amount  of  these  gases,  the  partial  pressure  of  0  or  of  CO2  is  high, 
these  gases  are  taken  up  again,  and  enter  into  a  condition  of  chemical 
combination. 

The  hsemoglobin  of  the  blood  in  the  pulmonary  capillaries  finds 
plenty  of  0  in  the  alveoli ;  hence,  it  unites  with  the  0  owing  to  the 
high  partial  pressure  of  the  0  in  the  lung,  and  so  forms  the  compound 
oxyhsemoglobin.     On  its  course  through  the  capillaries  of  the  systemic 


264  CUTANEOUS  RESPIRATION. 

circulation,  the  oxyhsemoglobin  of  the  blood  comes  into  relation  with 
tissues  poor  in  0;  the  oxyhsemoglobin  is  dissociated,  the  0  is  supplied  to 
the  tissues,  and  the  blood  freed  from  this  0,  returns  to  the  right  heart, 
and  passes  to  the  lungs,  where  it  takes  up  new  0. 

The  blood  whilst  circulating  meets  with  most  COg  in  the  tissues; 
the  high  partial  pressure  of  the  COg  in  the  tissues  causes  the  COg  to 
unite  with  certain  constituents  in  the  blood  so  as  to  form  chemical 
compounds,  which  carry  the  COg  from  the  tissues  to  the  lungs.  In 
the  air  of  the  lungs,  however,  the  partial  pressure  of  the  CO2  is  very 
low,  dissociation  of  these  chemical  compounds  occurs  under  the  low 
partial  pressure,  and  the  CO2  passes  into  the  air-cells  of  the  lung,  from 
which  it  is  expelled  during  expiration.  It  is  evident  that  the  giving 
up  of  0  from  the  blood  to  the  tissues,  and  the  absorption  of  CO2  from 
the  tissues,  go  on  side  by  side  and  take  place  simultaneously,  while  in 
the  lungs  the  reverse  processes  occur  also  simultaneously. 


131.  Cutaneous  Respiration. 

Methods. — If  a  man  or  an  animal  be  placed  in  the  chamber  of  a  respiratory- 
apparatus  (Scharling's,  or  v.  Pettenkofer's),  and  if  tribes  be  so  arranged  that  the 
respiratory  gases  do  not  enter  the  chamber,  of  course  we  obtain  only  the 
"perspiration^'  of  the  skin  in  the  chamber.  It  is  less  satisfactory  to  leave  the 
head  of  the  person  outside  the  chamber,  while  the  neck  is  fixed  air-tight  in  the  wall 
of  the  chamber.  The  extent  of  the  cutaneous  respiration  of  a  limb  may  be  ascer- 
tained by  enclosing  it  in  an  air-tight  vessel  (Rohrig)  similar  to  that  used  for  the 
arm  in  the  plethysmograph  (p.  198). 

Loss  "by  Skin. — A  healthy  man  loses  by  the  skin,  in  24  hours,  ^V  of 
his  body-weight  (S6guin),  which  is  greater  than  the  loss  by  the  lungs, 
in  the  ratio  of  3  :  2  (Valentin,  1843),  Only  10  grammes — 150  grains 
(Scharling),  or  it  may  be  3"9  grammes — 60  grains  (Aubert),  of  the 
entire  loss  is  due  to  the  CO2  given  off  by  the  skin.  The  remainder  of 
the  excretion  from  the  skin  is  due  to  water,  containing  a  few  salts  in 
solution.  When  the  surrounding  temperature  is  raised,  the  CO2  is 
increased  (Gerlach),  in  fact  it  may  be  doubled  (Aubert) ;  violent 
muscular  exercise  has  the  same  effect. 

0  Absorbed. — The  0  taken  up  by  the  skin  is  either  equal  to 
(Regnault  and  Keiset),  or  slightly  less  than,  the  CO2  given  off.  As  the 
CO2  excreted  by  the  skin  is  only  -wl-^  of  that  excreted  by  the  lungs, 
while  the  0  taken  in  =  yl^  of  that  taken  in  by  the  lungs,  it  is  evident 
that  the  respiratory  activity  of  the  skin  is  very  slight.  Animals  whose  skin 
has  been  covered  by  an  impermeable  varnish  die  not  from  suflFocation, 
but  from  other  causes. — (See  Artificial  Diminution  of  Tentperature.) 


INTERNAL  RESPIRATION.  265 

In  animals  with  a  thin  moist  epidermis  (frog)  the  exchange  of  gases  is  much 
greater,  and  in  them  the  skin  so  far  supports  the  lungs  in  their  function,  and  may 
even  partly  replace  them  functionally.  In  manrnaals  with  thick  dry  cutaneous 
appendages,  the  exchange  of  gases  is,  again,  much  less  than  in  man. 

132.  Internal  Respiration. 

Where  COo  is  Formed. — By  the  term  "  internal  respiration"  is  under- 
stood the  exchange  of  gases  between  the  capillaries  of  the  systemic 
circulation  and  the  tissues  of  the  various  organs  of  the  body.  As  the 
organic  constituents  of  the  tissues,  during  their  activity,  undergo  gradual 
oxidation,  and  form,  amongst  other  products,  CO^ :  we  may  assume — (1.) 
That  the  chief  focus  for  the  absorption  of  0  and  the  formation  of  CO., 
is  to  be  sought  for  within  the  tissues  themselves.  That  the  O  from 
the  blood  in  the  capillaries  rapidly  penetrates  or  diffuses  into  the 
tissues  is  shown  by  the  fact,  that  the  blood  in  the  capillaries  rapidly 
loses  0  and  gains  COj,  while  blood  containing  0,  and  kept  warm  out- 
side the  body,  changes  very  slowly  and  incompletely.  If  portions  of 
fresh  tissues  be  placed  in  defibrinated  blood  containing  0,  then  the  O 
rapidly  disappears  (Hoppe-Seyler).  Frogs  deprived  of  their  blood 
exhibit  an  exchange  of  gases  almost  as  great  as  normal.  This  shows 
that  the  exchange  of  gases  must  take  place  in  the  tissues  themselves 
(Pfliiger  and  Oertmann).  If  the  chief  oxidations  took  place  in  the 
blood  and  not  in  the  tissues,  then,  during  suffocation,  Avhen  0  is 
excluded,  the  substances  which  use  up  0,  i.e.,  those  substances  which 
act  as  reducing  agents,  ought  to  accumulate  in  the  blood.  But  this  is 
not  the  case,  for  the  blood  of  asphyxiated  animals  contains  mere  traces 
of  reducing  materials  (Pfliiger).  It  is  difficult  to  say  how  the  0  is 
absorbed  by  the  tissues,  and  what  becomes  of  it  immediately  it  comes 
in  contact  with  the  living  elements  of  the  tissues.  Perhaps  it  is 
temporarily  stored  up,  or  it  may  form  certain  intermediate  less  oxidised 
compounds.  This  may  be  followed  by  a  period  of  rapid  formation  and 
excretion  of  COo.  On  this  supposition,  it  is  evident  that  the  absorption 
of  0  and  the  excretion  of  CO.  need  not  occur  to  the  same  extent,  so 
that  the  amount  of  COo  given  off  at  any  period  is  not  necessarily  an 
index  of  the  amount  of  0  absorbed  during  the  same  period. 

[There  are  two  views  as  to  where  the  COj  is  formed  as  the  blood 
passes  through  the  tissues.  One  view  is  that  the  seat  of  oxidation  is  in 
the  blood  itself,  and  the  other  is  that  it  is  formed  in  the  tissues.  If 
we  knew  the  tension  of  the  gases  in  the  tissues  the  problem  would  be 
easUy  solved,  but  we  can  only  arrive  at  a  knowledge  of  this  subject 
indirectly,  in  the  following  ways]  : — 

CO2  ia  Cavities. — That  the  CO2  is  formed  in  the  tissues  is  supported  by  the 
fact,  that  the  amount  of  CO2  in  the  fluids  of  the  cavities  of  the  body  is  greater 
than  the  CO2  in  the  blood  of  the  capillaries. 


266  TENSION  OF  THE  GASES  IN    CAVITIES  AND   LYMPH, 

Pfluger  and  Strassburger  found  the  tension  of  CO2  to  be,  in 


Mm. 


Arterial  blood,     .      21  "28  Hg.  tension. 
Peritoneal  cavity,        58 '5     ,,         ,, 
Acid  urine,  .       68 '0     ,,         ,, 


Mm. 
Bile,       .        .         .50*0  Hg.  tension. 
Hydrocele  fluid,     .      46*5     ,,        ,, 


The  large  amount  of  CO2  in  these  fluids  can  only  arise  from  the  CO2  of  the 
tissues  passing  into  them. 

Gases  of  Lymph. — In  the  lymph  of  the  ductus  thoracicus  the  tension  of 
C02=33'4  to  37 "2  mm.  Hg.,  which  is  greater  than  in  arterial  blood,  but  consider- 
ably less  than  in  venous  blood  (41 '0  mm.  Hg).  This  does  not  entitle  us  to 
conclude  that  in  the  tissues  from  which  the  lymph  comes,  only  a  small  quantity  of 
CO2  is  formed,  but  rather  that  in  the  lymph  there  is  less  attraction  for  the  CO2 
formed  in  the  tissues  than  in  the  blood  of  the  capillaries,  where  chemical  forces  are 
active  in  causing  it  to  combine,  or  that  in  the  course  of  the  long  lymph-current, 
the  CO2  is  partly  given  back  to  the  tissues,  or  that  CO2  is  formed  in  the  blood 
itself.  Further,  the  muscles,  which  are  by  far  the  largest  producers  of  CO2,  con- 
tain few  lymphatics,  nevertheless  they  supply  much  CO2  to  the  blood. 

The  amount  of  free  "non-fixed"  CO2  contained  in  the  juices  and  tissues  indi- 
cates that  the  CO2  passes  from  the  tissues  into  the  blood;  still,  Preyer  believes  that 
in  venoiis  blood  CO2  undergoes  chemical  combination.  The  exchange  of  O  and 
CO2  varies  much  in  the  diS"erent  tissues.  The  muscleS  are  the  most  important 
organs,  for  in  their  active  condition  they  excrete  a  large  amount  of  CO2,  and  use 
up  much  O.  The  0  is  so  rapidly  used  up  by  them  that  no  free  O  can  be  pumped 
out  of  muscular  tissue  (L.  Hermann).  The  exchange  of  gases  is  more  vigorous 
during  the  activity  of  the  tissues.  Nor  are  the  salivary  glands,  kidneys,  and 
pancreas  any  exception,  for  although  when  these  organs  are  actively  secreting,  the 
blood  flows  out  of  the  dilated  veins  in  a  bright  red  stream,  still  the  relative 
diminution  of  CO2  is  more  than  compensated  by  the  increased  volume  of  blood 
which  passes  through  these  organs. 

(2.)  In  the  BLOOD  itself,  as  in  all  tissues,  0  is  used  up  and  COg  is 
formed.  This  is  proved  by  the  following  facts  : — That  blood  with- 
drawn from  the  body  becomes  poorer  in  0  and  richer  in  COg ;  that  in 
the  blood  of  asphyxia,  free  from  0,  and  in  the  blood-corpuscles 
(Afanassieff),  there  are  slight  traces  of  reducing  agents,  which  become 
oxidised  on  the  addition  of  0  (A.  Schmidt).  Still,  this  process  is 
comparatively  insignificant  as  against  that  which  occurs  in  all  the  other 
tissues.  That  the  walls  of  the  vessels — more  especially  the  muscular 
fibres  in  the  walls  of  the  small  arteries — use  0  and  produce  CO2  is 
unquestionable,  although  it  is  so  slight  that  the  blood  in  its  whole 
arterial  course  undergoes  no  visible  change, 

Ludwig  and  his  pupils  have  proved  that  CO2  is  actually  formed  in  the  blood. 
If  the  easily  oxidisable  lactate  of  soda  be  mixed  with  blood,  and  this  blood  be 
caused  to  circulate  in  an  excised  but  still  living  organ,  such  as  a  lung  or  kidney, 
more  0  is  used  up  and  more  CO2  is  formed  than  in  unmixed  blood  similarly 
transfused. 

(3.)  That  the  tissues  of  the  living  lungs  use  0  and  give  off  CO2  is 

probable.     When  C.  Ludwig  and  Miiller  passed  arterial  blood  through 

the  blood-vessels  of  a  lung  deprived  of  air,  the  0  was  diminished  and 

the  CO^  increased. 


RESPIRATION   IN   A  CLOSED   SPACE.  267 

As  the  total  amount  of  COg  and  0  found  in  the  entire  blood,  at  any- 
one time,  is  only  4  grammes,  and  as  the  daily  excretion  of  COg  =  900 
grammes,  and  the  0  absorbed  daily  =744  grammes,  it  is  clear  that 
exchange  of  gases  must  go  on  with  great  rapidity,  that  the  0  absorbed 
must  be  used  quickly,  and  the  COg  must  be  excreted. 

Still,  it  is  a  striking  fact  that  oxidation-processes  of  such  magnitude  as,  e.g., 
the  union  of  C  to  form  COo,  occur  at  a  relatively  low  temperature  of  the  blood 
and  the  tissues.  It  has  been  assumed  that  the  blood  acts  as  an  ozone-producer, 
and  transfers  this  active  form  of  O  to  the  tissues.  Liebig  showed  that  the 
alkaline  reaction  of  most  of  the  juices  and  tissiies  favours  the  processes  of  oxida- 
tion. Numerous  organic  substances,  which  are  not  altered  by  0  alone,  become 
rapidly  oxidised  in  the  presence  of  free  alkalies,  e.g.,  gallic  acid,  pyrogallic  acid, 
and  sugar;  while  many  organic  acids,  which  are  unaffected  by  ozone  alone,  are 
changed  into  carbonates,  when  in  the  form  of  alkaline  salts  (Gorup-Besanez),  and  in 
the  same  way,  when  they  are  introduced  into  the  body  in  the  form  of  acids,  they 
are  partly  or  wholly  excreted  in  the  urine,  but  when  they  are  administered  as 
alkaline  compoimds  they  are  changed  into  carbonates. 

133.  Respiration  in  a  Closed  Space. 

Eespiration  in  a  closed  or  confined  space  causes  : — (1)  a  gradual 
diminution  of  0 ;  (2)  a  simultaneous  increase  of  COg ;  (3)  a  diminu- 
tion in  the  volume  of  the  gases.  If  the  space  be  of  moderate  dimensions, 
the  animal  uses  up  almost  all  the  0  contained  therein  (Nysten).  and 
dies  ultimately  from  spasms  caused  by  the  asphyxia.  The  0  is  absorbed, 
therefore — independently  of  the  laws  of  absorption — by  chemical  means. 
The  0  in  the  blood  is  almost  completely  used  up  (Setschenow).  In  a 
larger  closed  space,  the  COg  accumulates  rapidly,  before  the  diminution  of 
0  is  such  as  to  affect  the  life  of  the  animal.  As  CO.,  can  only  be  ex- 
creted from  the  blood  Avhen  the  tension  of  the  COg  in  the  blood  is  greater 
than  the  tension  of  COg  in  the  air,  as  soon  as  the  COg  in  the  surrounding 
air  in  the  closed  space  becomes  the  same  as  in  the  blood,  the  COg  will 
be  retained  in  the  blood,  and  finally  CO3  may  pass  back  into  the  body. 
This  occurs  in  a  large  closed  space,  when  the  amount  of  0  is  still 
suflScient  to  support  life,  so  that  death  occurs  under  these  circumstances 
(in  rabbits)  through  poisoning  with  COo,  causing  diminished  excitability, 
loss  of  consciousness,  and  lowering  of  temperature,  but  no  spasms 
(Worm  Miiller).  In  pure  0,  animals  breathe  in  a  normal  way;  the  quantity 
of  0  absorbed  and  the  CO2  excreted  is  quite  independent  of  the  percentage 
of  0,  so  that  the  former  occurs  through  chemical  agency  independent  of 
pressure.  In  closed  spaces  filled  with  0,  animals  died  by  re-absorption 
of  the  CO2  excreted.  Worm  Miiller  found  that  rabbits  died  after  absorb- 
ing CO2  equal  to  half  the  volume  of  their  body,  although  the  air  still 
contained  50  per  cent.  0.  Animals  can  breathe  quite  quietly  a  mixture 
of  air  containing  14"8  per  cent.  (20"9  per  cent,  normal);  with  7  per  cent. 


268  DYSPNCEA   AND   ASPHYXIA. 

they  breathe  with  difficulty;  with  4"5  per  cent,  there  is  marked  dyspnoea ; 
with  3  per  cent.  0  there  is  tolerably  rapid  asphyxia  (W.  Miiller).  The 
air  expired  by  man  normally  contains  14-18  per  cent.  0.  If  animals 
be  supplied  with  a  mixture  of  gases  similar  to  the  atmosphere,  in  which 
N  is  replaced  by  H,  they  breathe  quite  normally  (Lavoisier  and  Seguin) ; 
the  H  undergoes  no  great  change. 

Dyspnoea  occuz's  when  the  respired  air  is  deficient  in  0,  as  well  as  when  it  is 
overcharged  with  CO2,  but  the  dyspnoea  in  the  former  case  is  prolonged  and 
severe;  in  the  latter,  the  respiratory  activity  soon  ceases.  The  want  of  O  causes 
a  greater  and  more  prolonged  increase  of  the  blood-pressure  than  is  caused  by 
excess  of  COg.  Lastly,  the  consumption  of  0  in  the  body  is  less  affected  when  the 
0  in  the  air  is  diminished  than  when  there  is  excess  of  CO2.  If  air  containing  a 
diminished  amount  of  0  be  respired,  death  is  preceded  by  violent  phenomena  of 
excitement  and  spasms,  which  are  absent  in  cases  of  death  by  breathing  air  over- 
charged with  CO2.  In  poisoning  with  CO2.  the  excretion  of  CO2  is  greatly 
diminished,  while  with  diminution  of  0,  it  is  almost  unchanged  (C.  Friedlander 
and  E.  Herter). 

CI.  Bernard  found  that,  when  an  animal  breathed  in  a  closed  space,  it  became 
partially  accustomed  to  the  condition.  On  placing  a  bird  under  a  bell-jar,  it  lived 
several  hours  ;  but  if  several  hours  before  its  death  another  bird  fresh  from  the 
outer  air  were  placed  under  the  same  bell- jar,  the  second  bird  died  at  once,  with 
convulsions. 

Frogs,  when  placed  for  several  hours  in  air  devoid  of  0,  give  off  just  as  much 
CO2  as  in  air  containing  O,  and  they  do  this  without  any  obvious  disturbance 
(Pfiuger,  Aubert).  Hence,  it  appears  that  the  formation  of  CO2  is  independent  of 
the  absorption  of  0,  and  the  CO2  must  be  formed  from  the  decomposition  of  other 
compounds.  Ultimately,  however,  complete  motor  paralysis  occurs,  whilst  the 
circulation  remains  undisturbed  (Aubert). 


134.  Dyspnoea  and  Asphyxia. 

[The  causes  of  dyspnoea  have  already  been  referred  to  (§  111),  and 
those  of  asphyxia  are  referred  to  in  detail  in  vol.  ii.  under  Nervous 
Mechanism  of  Respiration.  If  from  any  cause,  an  animal  be  not  supplied 
with  a  due  amount  of  air,  normal  respiration  becomes  greatly  altered, 
passing  through  the  phases  of  hyperpnoea,  or  increased  respiration, 
dyspnoea  or  difficulty  of  breathing,  to  the  final  condition  of  suffocation 
or  asphyxia.  The  phenomena  of  asphyxia  may  be  developed  in  an 
animal  by  closing  its  trachea  by  means  of  a  clamp,  and  in  fact  by  any 
means  which  prevent  the  entrance  of  air  or  blood  into  the  lungs. 

The  phenomena  of  asphyxia  are  usually  divided  into  several  stages. 
— 1.  During  the  first  stage  there  is  hyperpnoea,  the  respirations  being 
deeper,  more  frequent,  and  laboured.  The  extraordinary  muscles  of 
respiration — ^both  those  of  inspiration  and  expiration — referred  to  in 
§118,  are  called  into  action,  the  condition  of  dyspnoea  being  rapidly 
produced,  and  the  struggle  for  air  becomes  more  and  more  severe. 
During  this  time  the  oxygen  of  the  blood  is  being  used  up,  the  blood 


PHENOMENA   OF  ASPHYXIA.  269 

itself  is  becoming  more  and  more  venous.  This  venous  blood  circulat- 
ing in  the  medulla  oblongata,  and  spinal  cord  stimulates  the  respiratory 
centres,  thus  causing  these  violent  respirations.  This  stage  usually 
lasts  about  a  minute  and  gradually  gives  place  to — 

2.  The  second  stage,  when  the  inspiratory  muscles  become  less  active, 
while  those  concerned  in  laboured  expiration  contract  energetically, 
and  indeed  almost  every  muscle  in  the  body  may  contract ;  so  that 
this  stage  of  violent  expiratory  efforts  ends  in  general  convulsions. 
The  convulsions  are  due  to  stimulation  of  the  respiratory  centres  by 
the  venous  blood.  The  convulsive  stage  is  short,  and  is  usually  reached 
in  a  little  over  one  minute.     This  storm  is  succeeded  by — 

3.  The  third  stage,  or  stage  of  exhaustion,  the  transition  being  usually 
somewhat  sudden.  This  condition  is  brought  about  by  the  venous 
l)lood  acting  on  and  paralysing  the  respiratory  centres.  The  pupils  are 
widely  dilated,  consciousness  is  abolished,  and  the  activity  of  the  reflex 
centres  is  so  depressed  that  it  is  impossible  to  discharge  a  reflex  act, 
even  from  the  cornea.  The  animal  lies  almost  motionless,  with  flaccid 
muscles,  and  to  all  appearance  dead,  but  every  now  and  again,  at  long 
intervals,  it  makes  a  few  deep  inspiratory  efi'orts,  showing  that  the 
respiratory  centres  are  not  quite,  but  almost  paralysed.  Gradually,  the 
pauses  become  longer  and  the  inspirations  feebler  and  of  a  gasping 
character.  As  the  venous  blood  circulates  in  the  spinal  cord  it  causes 
a  large  number  of  muscles  to  contract,  so  that  the  animal 
extends  its  trunk  and  limbs.  It  makes  one  great  inspiratory 
spasm,  the  mouth  being  widely  open  and  the  nostrils  dilated,  and 
ceases  to  breathe.  After  this  stage,  which  is  the  longest  and 
most  variable,  the  heart  becomes  paralysed,  partly  from  being 
over-distended  with  venous  blood,  and  partly,  perhaps,  from  the 
action  of  the  venous  blood  on  the  cardiac  tissues,  so  that  the  pulse 
can  hardly  be  felt.  To  this  pulseless  condition  the  term  "  asphyxia  " 
ought  properly  to  be  applied.  In  connection  with  the  resuscitation  of 
asphyxiated  persons,  it  is  important  to  note  that  the  heart  continues  to 
beat  for  a  few  seconds  after  the  respiratory  movements  have  ceased. 

The  whole  series  of  phenomena  occupies  from  3  to  5  minutes,  according 
to  the  animal  operated  on,  and  depending  also  upon  the  suddenness 
with  which  the  trachea  was  closed.  If  the  causes  of  suff'ocation  act  more 
slowly,  the  phenomena  are  the  same,  only  they  are  developed  more  slowly. 

The  Circulation. — The  post-mortem  appearances  in  man  or  in  an 
animal  are  generally  well  marked.  The  right  side  of  the  heart,  the 
pulmonary  artery,  the  venae  cavse,  and  the  veins  of  the  neck  are 
engorged  with  dark  venous  blood.  The  left  side  is  comparatively 
empty,  because  the  rigor  mortis  of  the  left  side  of  the  heart,  and  the 
elastic  recoil  of  the   systemic  arteries,  force  the   blood   towards  the 


270        THE   CHANGES   OF  THE   CIRCULATION   DURING  ASPHYXIA. 

systemic  veins.  The  hlood  itself  is  almost  black,  and  is  deprived  of  almost 
all  its  oxygen,  while  its  haemoglobin  is  nearly  all  in  the  condition  of 
reduced  haemoglobin,  while  ordinary  venous  blood  contains  a  considerable 
amount  of  reduced  and  oxyhsemoglobin.  The  blood  of  an  asphyxiated 
animal  practically  contains  none  of  the  latter,  and  much  of  the  former. 

It  is  important  to  study  the  changes  in  the  circulation  in  connection 
with  the  outward  phenomena  exhibited  by  an  animal  during  suffocation. 

We  may  measure  the  blood-pressure  in  any  artery  of  an  animal  while 
it  is  being  asphyxiated,  or  we  may  open  its  chest,  maintain  artificial  respi- 
ration, and  place  a  manometer  in  a  systemic  artery,  e.g.,  the  carotid, 
and  another  in  a  branch  of  the  pulmonary  artery.  In  the  latter  case, 
we  can  watch  the  order  of  events  in  the  heart  itself,  when  the  artificial 
respiration  is  interrupted.     It  is  well  to  study  the  events  in  both  cases. 

If  the  blood-pressure  be  measured  in  a  systemic  artery,  e.g.,  the 
carotid,  it  is  found  that  the  blood-pressure  rises  very  rapidly  and  to  a 
great  extent  during  the  first  and  second  stages ;  the  pulse-beats  at  first 
are  quicker,  but  soon  become  slower  and  more  vigorous.  During  the 
third  stage  it  falls  rapidly  to  zero.  The  great  rise  of  the  blood-pressure 
during  the  first  and  second  stages  is  chiefly  due  to  the  action  of  the 
venous  blood  on  the  general  vaso-motor  centre,  causing  constriction  of 
the  small  systemic  arteries.  The  peripheral  resistance  is  thus  greatly 
increased,  and  it  tends  to  cause  the  heart  to  contract  more  vigorously, 
but  the  slower  and  more  vigorous  beats  of  the  heart  are  also  partly 
due  to  the  action  of  the  venous  blood  on  the  cardio-inhibitory  centre  in 
the  meduUa. 

If  the  second  method  be  adopted,  viz.,  to  open  the  chest,  keep  up 
artificial  respiration,  and  measure  the  blood-pressure  in  a  branch  of  the 
pulmonary  artery,  as  weU  as  in  a  systemic  artery,  e.g.,  the  carotid — ^we 
find  that  when  the  artificial  respiration  is  stopped,  in  addition  to  the 
rise  of  the  blood-pressure  indicated  in  the  carotid  manometer,  the 
cavities  of  the  heart  and  the  large  veins  near  it  are  engorged  with 
venous  blood.  There  is,  however,  but  a  slight  comparative  rise  in  the 
blood-pressure  in  the  pulmonary  artery.  This  may  be  accounted  for, 
either  by  the  pulmonary  artery  not  being  influenced  to  the  same  extent 
as  other  arteries,  by  the  vaso-motor  centre,  or  by  its  greater  distensibility 
(Lichtheim — compare  §  88).  But,  as  the  heart  itself  is  supplied  through 
the  coronary  arteries  with  venous  blood,  its  action  soon  becomes 
weakened,  each  beat  becomes  feebler,  so  that  soon  the  left  ventricle 
ceases  to  contract,  and  is  unable  to  overcome  the  great  peripheral 
resistance  in  the  systemic  arteries,  although  the  right  ventricle  may 
stni  be  contracting.  As  the  blood  becomes  more  venous,  the  vaso- 
motor centre  becomes  paralysed,  the  small  systemic  arteries  relax,  and 
the  blood  flows  from  them  into  the  veins,  while  the  blood-pressure  in 


RESPIRATION   OP  FOREIGN   GASES.  271 

the  carotid  manometer  rapidly  falls.  The  left  ventricle,  now  relieved 
from  the  great  internal  pressure,  may  execute  a  few  feeble  beats,  but 
they  can  only  be  feeble,  as  its  tissues  have  been  subjected  to  the  action 
of  the  very  impure  blood.  More  and  more  blood  accumulates  in  the 
right  side  from  the  causes  already  mentioned. 

The  violent  inspiratory  efforts  in  the  early  stages  aspirate  blood 
from  the  veins  towards  the  right  side  of  the  heart,  but  of  course  this 
factor  is  absent  when  the  chest  is  opened.] 

[Recovery  from  the  condition  of  asphyxia.— If  the  trachea  of  a  dog  be 

closed  suddenly  and  completely,  the  average  duration  of  the  respiratory  move- 
ments is  4  minutes  5  seconds,  while  the  heart  continues  to  beat  for  about  7  minutes. 
Recovery  may  be  obtained  if  proper  means  be  adopted  before  the  heart  ceases  to 
beat;  but  after  this,  never. 

If  a  dog  be  drowned,  the  result  is  different.  After  complete  submersion  for  1^ 
minutes,  recovery  did  not  take  place.  In  the  case  of  drownmg,  air  passes  out  of 
the  chest,  and  water  is  inspired  into  and  fills  the  air-vesicles.  It  is  rare  for 
recovei-y  to  take  place  in  a  person  deprived  of  air  for  more  than  five  mmutes.  If 
the  statements  of  sponge-divers  are  to  be  trusted,  a  person  may  become  accustomed 
to  the  deprival  of  air  for  a  longer  time  than  usual.  In  cases  where  recovery  takes 
place  after  a  much  longer  period  of  submersion,  it  has  been  suggested  that,  in  these 
cases,  syncope  occurs,  the  heart  beats  but  feebly  or  not  at  all,  so  that  the 
oxygen  in  the  blood  is  not  used  up  with  the  same  rapidity.  It  is  a  well-known 
fact  that  newly-born  and  young  puppies  can  be  submerged  for  a  long  time  before 
they  are  suffocated.] 

Artificial  Respiration. — The  methods  of  performing  artificial  respira- 
tion in  persons  apparently  suffocated  are  fully  given  in  vol  ii,  under 

Nervous  Mechanism  of  Respiration. 


135.  Respiration  of  Foreign  Gases. 

No  gas  without  a  sufficient  admixture  of  O  can  support  life.  Even  with  com- 
pletely innocuous  and  indifferent  gases,  if  no  O  be  mixed  with  them,  they  cause 
suffocation  in  2  to  3  minutes. 

I.  Completely  indifferent  gases  are  N,  H,  GH4.  The  living  blood  of  an 
animal  breathing  these  gases  yields  no  O  to  them  (Pfluger). 

II.  Poisonous  gases.— («•)  Those  that  displace  O,  and  form  a  permanent 
stable  compound  with  the  haemoglobin— (1.)  CO  (§16  and  17).  (2.)  CNH 
(Hydrocyanic  acid)  displaces  (?)  O  from  hajmoglobin,  with  which  it  forms  a 
more  stable  compound  and  kills  exceedingly  rapidly.  It  prevents  0  being  changed 
into  ozone  in  the  blood.  Blood-corpuscles  charged  with  hydrocyanic  acid  lose  the 
property  of  decomposmg  hydric  peroxide  into  water  and  0  (§  17,  5). 

(6.)  Narcotic  gases.— {\.)  COo— v.  Pettenkofer  characterises  air  containing  O 
with  -1  p.c.  CO2  as  "bad  air  ;  "  still,  air  in  a  room  containuig  this  amount  of  CO2 
produces  a  disagreeable  feelmg  rather  from  the  impurities  mixed  with  it  than  from 
the  actual  amount  of  CO2  itself.  Air  containing  1  p.c.  CO2  produces  decided 
discomfort,  and  witli  10  p.c.  it  endangers  life,  while  larger  amounts  cause  death 
with  symptoms  of  coma.  (2.)  N2O  (nitrous  oxide)  respired,  mixed  with  |  volume 
O,  causes,  after  1  to  2  minutes,  a  short  temporary  stage  of  excitement  ("Laughing 
gas"  of  H.  Davy),  which  is  succeeded  by  unconsciousness,  and  afterwards  an 
increased  excretion  of  C02.    (3.)  Ozonised  air  causes  similar  effects  (Binz). 


272  ACCIDENTAL  IMPURITIES  IN   THE  AIR. 

(c.)  Reducing  gases. — (1.)  H2S  (sulphuretted  hydrogen)  rapidly  robs  blood- 
corpuscles  of  0  :  S  and  H2O  bemg  formed,  and  death  occurs  rapidly  before  the 
gas  can  decompose  the  hsemoglobin  (Hoppe-Seyler). 

(2. )  PH3 — Phosphuretted  hydrogen  is  oxidised  in  the  blood  to  form  phosphoric 
acid  and  water  with  decomposition  of  the  haemoglobin  (Dybkowski,  Koschlakoff, 
and  Popoff). 

(3.)  AsHs,  arseniuretted  hydrogen  and  SbHg,  antimoniuretted  hydrogen,  act 
like  PHg,  but  in  addition,  the  heemoglobin  passes  out  of  the  stroma  and  appears  in 
the  urine. 

(4.)  C2N'2,  cyanogen  absorbs  0,  and  decomposes  the  blood  (Rosenthal  and 
Laschkewitsch). 

III.  IrrespirablB  gases,  i.e.,  gases  which,  on  entering  the  larynx,  cause  reflex 
spasm  of  the  glottis.  When  introduced  into  the  trachea  they  cause  inflammation 
and  death.  Under  this  category  come  hydrochloric,  hydrofluoric,  sulphurous, 
nitrous,  and  nitric  acids,  ammonia,  chlorine,  fluoriae,  and  ozone. 


136.  Accidental  Impurities  of  the  Air. 

Dust  Particles. — Amongst  these  are  dust  particles  which  occur  in  enormous 
amount  suspended  in  the  air,  and  thereby  act  injuriously  upon  the  respiratory 
organs.  The  ciliated  epithelium  of  the  respiratory  passages  eliminates  a  large 
number  of  them.  Some  of  them,  however,  reach  the  air-vesicles  of  the  lung, 
where  they  penetrate  the  epithelium,  reach  the  interstitial  lung-tissue  and  lym- 
phatics and  so  pass  with  the  lymph-stream  into  the  bronchial  glands.  Particles 
of  coal  or  charcoal  are  found  in  the  lungs  of  all  elderly  individuals,  and  blacken 
the  alveoli.  In  moderate  amount  these  black  particles  do  not  seem  to  do  any 
harm  in  the  tissues,  but  when  there  are  large  accumulations  they  give  rise  to  lung 
affections,  which  lead  to  disintegration  of  these  organs.  [In  coal-miners,  for 
example,  the  lung-tissues  along  the  track  of  the  lymphatics  and  in  the  bronchial 
glands  are  quite  black,  constituting  "  coal-miners'  lung."]  In  many  trades  various 
particles  occur  in  the  air;  miners,  grinders,  stone-masons,  file-makers,  weavers, 
spinners,  tobacco  manufacturers,  millers,  and  bakers,  suffer  from  lung  affections 
caused  by  the  introduction  of  particles  of  various  kinds  inhaled  during  the  time 
they  are  at  work. 

There  seems  no  doubt  that  the  seeds  of  some  contagious  diseases  may  be  inhaled. 
Diphtheritic  bacteria  become  localised  in  the  pharynx  and  in  the  larynx — 
glanders  in  the  nose — measles  in  the  bronchi — hay-monads  in  the  nose.  Many 
seeds  of  disease  pass  into  the  mouth  along  with  air,  are  swallowed,  and  undergo 
development  in  the  intestinal  tract,  as  is  probably  the  case  in  cholera  and  typhoid 
fever. 

137.  Ventilation  of  Rooms. 

Presh  air  is  as  necessary  for  the  healthy  as  for  the  sick.  Every  healthy  person 
ought  to  have  a  cubic  space  of  800  cubic  feet,  and  every  sick  person  1000  cubic 
feet  of  space.  [The  space  allowed  per  individual  varies  greatly,  but  1000  cubic 
feet  is  a  fair  average.  If  the  air  m  this  space  is  to  be  kept  sweet,  so  that  the  CO2 
does  not  exceed  '06  p.c,  2000  cubic  feet  of  air  per  hour  must  be  supplied.]  In 
France  only  42  cubic  feet  per  head  are  allowed  in  barracks,  60  cubic  feet  in 
hospitals.  In  Prussia  in  barracks  420-500  cubic  feet  are  allowed  for  every 
soldier,  for  hospital  600-720;  in  England  600  cubic  feet  per  head.  When  there 
is  overcrowding  in  a  room  the  amount  of  CO2  increases,  v,  Pettenkofer  found 
the  normal  amount  of  CO2  ( "04  to  '05  per  1000)  increased  in  comfortable  rooms  to 


FORMATION   OF  MUCUS   IN   THE  RESPIRATORY   PASSAGES.       273 

0  "54^0  7  per  1000;  in  badly  ventilated  sick  chambers  =  2*4;  in  overcrowded 
anditoriums,  3  "2 ;  in  pits  =  4-9 ;  in  school-rooms,  7  '2  per  1000.  Although  it  is  not  the 
quantity  of  CO2  which  makes  the  air  of  an  overcrowded  room  injurious,  but  the 
excretions  from  the  outer  and  inner  surfaces  of  the  body,  which  give  a  distinct 
odour  to  the  air,  quite  recognisable  by  the  sense  of  smell,  still,  the  amount  of  CO2 
is  taken  as  an  index  of  the  presence  and  amount  of  these  other  deleterious  sub- 
stances. The  question  as  to  whether  the  ventilation  of  a  room  or  ward  occupied 
by  persons  is  suflScient,  is  ascertained  by  estimating  the  amount  of  CO2.  A  room 
which  does  not  give  a  disagreeable,  somewhat  stuffy,  odour  has  less  than  0*7  per 
1000  of  CO2,  while  the  ventilation  is  certainly  insufficient  if  the  CO2  =  1  per  1000. 

As  the  air  contains  only  0'0005  cubic  meter  CO2  in  1  cubic  meter  of  air,  and  as 
an  adult  produces  hourly  0'0226  cubic  meters  CO2,  calculation  shows  that  every 
person  requires  113  cubic  meters  of  fresh  air  per  hour,  if  the  CO2  is  not  to  exceed 
0-7  per  1000 :  for  0*7  :  1000  =  (0-0226  +  x  x  O'OOOS)  :x,  i.e.,  x  =  113. 

In  ordinary  rooms,  where  every  person  is  allowed  the  necessary  space  (1000  cubic 
feet)  the  air  is  sufficiently  renewed  by  means  of  the  pores  in  the  walls  of  the  room, 
by  the  opening  and  shutting  of  doors,  and  by  the  fireplace,  provided  the  damper 
is  kept  open. 

It  is  most  important  to  notice  that  the  natural  ventilation  be  not  interfered  with 
by  dampness  of  the  walls,  for  this  influences  the  pores  very  greatly.  At  the  same 
time,  damp  walls  are  injurious  to  health  by  conducting  away  heat,  and  in  them  the 
germs  of  infectious  diseases  may  develop  (Lindwurm). 


138.    Formation  of  Mucus  in  the  Respiratory 
Passages— Sputum. 

The  respiratory  mucous  membrane  is  covered  normally  with  a  thin 
layer  of  mucus  (Fig.  97).  By  its  presence  this  substance  so  far  inhibits 
the  formation  of  new  mucus  by  protecting  the  mucous  glands  from  the 
action  of  cold  or  other  irritative  agents.  New  mucus  is  secreted  as  that 
already  formed  is  removed.  An  increased  secretion  accompanies  con- 
gestion of  the  respiratory  mucous  membrane.  Division  of  the  nerves 
on  one  side  of  the  trachea  (cat)  causes  redness  of  the  tracheal  mucous 
membrane  and  increased  secretion  (Rossbach). 

Eflfects  of  reagents  on  the  mucous  secretion.— If  ice  be  placed  on  the  belly 

of  an  animal  so  as  to  cause  the  animal  to  "  take  a  cold,^'  the  respiratory  mucous 
membrane  first  becomes  pale,  and  afterwards  there  is  a  copious  mucous  secretion, 
the  membrane  becoming  deeply  congested.  The  injection  of  sodium  carbonate 
and  ammonium  chloride  limits  the  secretion.  The  local  application  of  alum, 
silver  nitrate,  or  tannic  acid  makes  the  mucous  membrane  dry,  and  the  epithelium 
is  shed.  The  secretion  is  excited  by  apomorphin,  emetin,  pilocarpin,  and 
ipecacuanha,  while  it  is  limited  by  atropin  and  morphia  (Rossbach). 

Normal  Sputum. — Under  normal  circumstances  some  mucus — mixed 
with  a  little  saliva — may  be  coughed  up  from  the  back  of  the  throat. 
In  catarrhal  conditions  of  the  respiratory  mucous  membrane,  the  sputum 
is  greatly  increased  in  amount,  and  is  often  mixed  with  other  character- 
istic products.     Microscopically,  sputum  contains  : — 

1.  Epithelial  cells — chiefly  squames  from   the  mouth  and  pharynx 

18 


274 


THE   SPUTUM. 


(Fig.  115),  more  rarely  alveolar  epithelium  and  ciliated  epithelium  (7) 
from  the  respiratory  passages.  The  epithelial  cells  are  often  altered, 
having  undergone  maceration  or  other  changes.  Thus  some  cells  may 
have  lost  their  cilia  (6). 

The  epithelium  of  the  alveoli  (2)  is  squamous  epithelium,  the  cells  being  2  to  4 
times  the  breadth  of  a  colourless  blood-corpuscle.  These  cells  occur  chiefly  ia  the 
momiag  sputum  in  individuals  over  30  years  of  age.  In  younger  persons  their 
presence  indicates  a  pathological  condition  of  the  pulmonary  parenchyma 
(Guttman,  H.  Schmidt,  and  Bizzozero).  They  often  undergo  fatty  degeneration, 
and  they  may  contain  pigment  granules  (3);  or,  they  may  present  the  appearance 
of  what  Buhl  has  called  "myelin  degenerated  cells f  i.e.,  cells  filled  with  clear 
refractive  drops  of  various  sizes,  some  colourless,  others  coloured  particles,  the 
latter  having  been  absorbed  (4).  Mucin  in  the  form  of  myelin  drops  (5)]  is 
always  present  in  sputum. 

2.  Lymphoid  cells  (9)  are  to  be  regarded  as  colourless  blood-corpuscles 
which  have  wandered  out  of  the  blood-vessels;  they  are  most  numerous 
in  yellow  sputum,  and  less  numerous  in  the  clear,  mucus-like  excretion. 
The  lymph-cells  often  present  alterations  in  their  characters ;  they  may 
be  shrivelled  up,  fatty,  or  present  a  granular  appearance. 


Fig.  115. 

Various  objects  fomid  in  sputum— 1,  Detritus  and  particles  of  dust;  2,  alveolar 
epithelium  with  pigment;  3,  fatty  and  partly  pigmented  alveolar  epithelium; 
4,  alveolar  epithelium  containing  myelin-forms ;  5,  free  myelin-forms ;  6,  7, 
ciliated  epithelium,  some  changed,  others  without  cilia;  8,  squamous  epithelium 
from  the  mouth;  9,  leucocytes;  10,  elastic  fibres;  11,  fibrin-cast  of  a  small 
bronchus;  12,  leptothrix  buccalis  with  cocci,  bacteria,  and  spirochseti;  a, 
fatty  acid  crystals  and  free  fatty  granules;  b,  hsematoidin;  c,  Charcot's 
crystals;  d,  Cholesterin. 


ACTION    OF  THE   ATMOSPHERIC    PRESSURE.  275 

The  fluid  substance  of  the  sputum  contains  mucli  mucus  arising  from 
the  mucous  glands  and  goblet  cells ;  together  with  nuclein,  and  lecithin, 
and  the  constituents  of  saliva  according  to  the  amount  of  the  latter 
mixed  with  the  secretion.  Albumin  occurs  only  during  inflammation  of 
the  respiratory  passages,  and  its  amount  increases  with  the  degree  of 
inflammation.     Urea  has  been  found  in  cases  of  nephritis. 

Pathological.— In  cases  of  catarrh,  the  sputum  is  at  first  usually  sticky  and 
clear  (sputa  cruda),  but  later  it  becomes  more  firm  and  yellow  (sputa  cocta). 
Viider  jMthological  conditions  there  may  be  found  in  the  sputum— (a.)  Red  blood- 
corimscles  from  rupture  of  a  blood-vessel.  (6.)  Elastic-fibres  (10)  from  disintegration 
of  the  alveoli  of  the  lung;  usually  the  bundles  are  tine,  curved,  and  the  fibres 
branched.  [In  certam  cases  it  is  well  to  add  a  solution  of  caustic  potash,  which 
dissolves  the  other  elements  and  leaves  the  elastic  fibres  untouched.]  Their  pre- 
sence always  indicates  destruction  of  the  lung -tissue,  (c.)  Colourless  plugs  of 
fibrin  (11),  casts  of  the  smaller  or  larger  bronchi,  occur  in  some  cases  of  fibrinous 
exudation  mto  the  finer  air-passages,  (d.)  Crystals  of  various  kinds— Crystals  of 
fatty  acids  (Fig.  115,  a)  in  bundles  of  fine  needles.  They  indicate  great  decomposition 
of  the  stagnant  secretion— colourless,  sharp-pointed,  octagonal,  or  rhombic  plates 
—(c)  (Charcot's  crystals)  of  unknown  nature  (perhaps  tyrosin),  Ha^matoidin  (6) 
and  cholesterin  crystals  (d)  occur  much  more  rarely.  (/.)  Fungi  and  other  lower 
organisms  frequently  occur.  The  threads  of  leptothrix  huccalis  (12) ;  Oidium 
albicans  in  the  mouth  of  sucklings,  rod-shaped  bacilli  and  bacteria.  In  phthisis, 
the  tubercle-bacillus  of  Koch. 

Abnormal  coloration  of  the  sputum— red  from  blood— when  the  blood  remains 
long  in  the  lung  it  undergoes  a  regular  series  of  changes  and  tinges  the  sputum 
dark  red,  bluish  brown,  brownish  yellow,  deep  yellow,  yellowish  green,  or  grass 
green.  The  sputum  is  sometimes  yellow  in  jaundice.  The  sputum  may  be  tmged 
by  what  is  inspired  [as  in  the  case  of  the  "black-spit"  of  miners.] 

The  odour  of  the  sputum  is  more  or  less  unpleasant.  It  becomes  very  disagree- 
able when  it  has  remained  long  in  pathological  lung  cavities,  and  it  is  stinking  in 
gangrene  of  the  lung. 

139.    Action  of  the  Atmospheric  Pressure. 

At  the  normal  pressure  of  the  atmosphere  (height  of  the  barometer, 
760  millimetres  Hg.),  pressure  is  exerted  upon  the  entire  surface  of  the 
body=  15,000  to  20,000  kilos.,  according  to  the  extent  of  the  superficial 
area  (Galileo).  This  pressure  acts  equally  on  all  sides  upon  the  body, 
and  occurs  also  in  all  internal  cavities  containing  air,  both  those  that  are 
constantly  filled  with  air  (the  respiratory  passages  and  the  spaces  in  the 
superior  maxillary,  frontal,  and  ethmoid  bones),  and  those  that  are 
temporarily  in  direct  communication  with  the  outer  air  (the  digestive 
tract  and  tympanum  ).  As  the  fluids  of  the  body  (blood,  lymph,  secre- 
tions, parenchymatous  juices)  are  practically  incompressible,  their  volume 
remains  practically  unchanged  under  the  pressure ;  but  they  will  absorb 
gases  from  the  air  corresponding  to  the  prevailing  pressure  (i.e.,  the 
partial  pressure  of  the  individual  gases),  and  according  to  their  tempera- 
ture (compare  §  33). 


276  ACTION  OF  DIMINISHED  ATMOSPHERIC  PRESSURE, 

The  solids  consist  of  elementary  parts  (cells  and  fibres),  each  of  which 
presents  only  a  microscopic  surface  to  the  pressure,  so  that  for  each  cell 
the  prevaiKng  pressure  of  the  air  can  only  be  calculated  at  a  few 
millimetres — a  pressure  under  which  the  most  delicate  histological 
tissues  undergo  development.  As  an  example  of  the  action  of  the 
pressure  of  the  atmospheric  pressure  upon  large  masses,  take  that 
brought  about  by  the  adhesion  of  the  smooth,  sticky,  moist  articular 
surfaces  of  the  shoulder  and  hip  joints.  In  these  cases,  the  arm  and 
the  leg  are  supported  without  the  action  of  muscles.  The  thigh- 
bone remains  in  its  socket  after  section  of  all  the  muscles  and  its 
capsule  (Brothers'  Weber).  Even  when  the  colytoid  cavity  is  perforated, 
the  limb  does  not  fall  out  of  its  socket.  The  ordinary  barometric 
variations  affect  the  respiration — a  rise  of  the  barometric  pressure 
excites,  while  a  fall  diminishes,  the  respirations.  The  absolute  amount 
of  CO2  remains  the  same  (§  127,  8). 

A  Great  Diminution  of  the  Atmospheric  Pressure,  such  as  occurs  in 

ballooning  (highest  ascent,  8,600  meters),  or  ui  ascending  mountains,  causes  a  series 
of  characteristic  phenomena  :— (1.)  In  consequence  of  the  diminution  of  the  pressure 
upon  the  parts  directly  in  contact  with  the  air,  they  become  greatly  congested, 
hence,  there  is  redness  and  swelling  of  the  skin  and  free  mucous  membranes;  there 
may  be  hsemorrhage  from  the  nose,  lungs,  gums,  turgidity  of  the  cutaneous 
veins  ;  copious  secretion  of  sweat,  great  secretion  of  mucus.  (2.)  A  feeling  of 
weight  in  the  limbs,  a  pressing  outwards  of  the  tympanic  membrane  (until  the 
tension  is  equilibrated  by  opening  of  the  Eustachian  tube),  and  as  a  consequence 
noises  in  the  ears  and  difficulty  of  hearing.  (3. )  In  consequence  of  the  diminished 
tension  of  the  O  in  the  air  (§  129),  there  is  difficulty  of  breathing,  pain  in  the 
chest,  whereby  the  respirations  (and  pulse)  become  more  rapid,  deeper,  and 
irregular.  When  the  atmospheric  pressure  is  diminished  ^-^,  the  amount  of  O 
in  the  blood  is  diminished  (Bert,  Frankel  and  Geppert),  the  CO2  is  imperfectly  re- 
moved from  the  blood,  and  in  consequence  there  is  diminished  oxidation  within 
the  body.  When  the  atmospheric  pressure  is  diminished  to  one-half,  the  amount 
of  CO2  in  arterial  blood  is  lessened ;  and  the  amount  of  N  diminishes  proportionally 
with  the  decrease  of  the  atmospheric  pressure  (Frankel and  Gepert).  The  diminished 
tension  of  the  air  prevents  the  vibrations  of  the  vocal  cords  from  occurring  so 
forcibly,  and  hence  the  voice  is  feeble.  (5. )  In  consequence  of  the  amount  of 
blood  in  the  skin,  the  internal  organs  are  relatively  anaemic ;  hence,  there  is 
diminished  secretion  of  urine,  muscular  weakness,  disturbances  of  digestion,  dull- 
ness of  the  senses,  and  it  may  be  unconsciousness,  and  all  these  phenomena  are 
intensified  by  the  conditions  mentioned  under  (3).  Some  of  these  phenomena  are 
modified  by  usage.  The  highest  limit  at  which  a  man  may  still  retain  his  senses 
is  placed  by  Tissandier  at  an  elevation  of  8,000  metres  (280  mm.  Hg).  In  dogs 
the  blood-pressure  falls,  and  the  pulse  becomes  small  and  diminished  in  frequency, 
when  the  atmospheric  pressure  falls  to  200  mm.  Hg. 

Those  who  live  upon  high  mountains  suffer  from  a  disease  {mat  de  montagne), 
which  consists  essentially  in  the  above  symptoms,  although  it  is  sometimes  com- 
plicated with  anaemia  of  the  internal  organs.  Al.  v.  Humboldt  found  that  in  those 
who  lived  on  the  Andes,  the  thorax  was  capacious.  At  6,000  to  8,000  feet  above 
sea-level,  water  contains  only  one-third  of  the  absorbed  gases,  so  that  fishes  cannot 
live  in  it  (Boussingault).  Animals  maybe  subjected  to  a  farther  diminution  of  the 
atmospheric  pressure,  by  being  placed  under  the  receiver  of  an  air-pump.      Birds 


COMPARATIVE   AND   HISTORICAL.  277 

die  when  the  pressure  is  reduced  to  120  mm.  Hg. ;  mammals  at  40  mm.  Hg.;  frogs 
endure  repeated  evacuations  of  the  receiver,  whereby  they  are  miich  dis- 
tended, owing  to  the  escape  of  gases  and  water,  but  after  the  entrance  of  air  they 
become  greatly  compressed.  The  cause  of  death  in  mammals  is  ascribed  by 
Hoppe-Seyler  to  the  evolution  of  bubbles  of  gas  in  the  blood ;  these  bubbles  stop 
up  the  capillaries,  and  the  circulation  is  arrested.  Local  diminution  of  the  atmo 
.•spheric  pressure  causes  marked  congestion  and  swelling  of  the  part,  as  occurs 
when  a  cupping-glass  is  used. 

Great  Increase  of  the  Atmospheric  Pressure.— The  phenomena,  which 

are,  for  the  most  part,  the  reverse  of  the  foregoing,  have  been  observed  in  pneumatic 
cabinets  and  in  diving  bells,  where  men  may  work  even  under  4i  atmospheres 
pressure.  The  phenomena  are  :  — (1.)  Paleness  and  dryness  of  the  external  sur- 
faces, collapse  of  the  cutaneous  veins,  diminution  of  perspiration,  and  mucous 
secretions.  (2.)  The  tympanic  membrane  is  pressed  inwards  (until  the  air  escapes 
through  the  Eustachian  tube,  after  causing  a  sharp  sound),  acute  sounds  are  heard, 
pain  in  the  ears,  and  difficulty  of  hearing.  (.3. )  A  feeling  of  lightness  and  freshness 
during  respiration,  the  respiration  becomes  slower  (by  2-4  per  minute),  inspiration 
easier  and  shorter,  expiration  lengthened,  the  pause  distinct.  The  capacity  of  the 
lungs  increases,  owing  to  the  freer  movement  of  the  diaphragm,  in  consequence  of 
the  diminution  of  the  intestinal  gases.  Owing  to  the  more  rapid  oxidations  in  the 
body,  muscular  movement  is  easier  and  more  active.  The  O  absorbed  and  the  CO2 
excreted  are  increased.  The  venous  blood  is  reddened.  (4. )  Difficulty  of  speaking, 
alteration  of  the  tone  of  the  voice,  inability  to  whistle.  (5.)  Increase  of  the  urinary 
secretion,  more  muscular  energy,  more  rapid  metabolism,  increased  appetite,  sub- 
jective feeling  of  warmth,  pulse  beats  slower,  and  pulse-curve  is  lower  (compare 
p.  150).  In  animals  subjected  to  excessively  high  atmospheric  pressure,  P.  Bert 
found,  that  the  arterial  blood  contained  30  vols,  per  cent.  0  (at  760  mm.  Hg. );  when 
the  amount  rose  to  35  vol.  per  cent.,  death  occurred  with  convulsions.  Compiessed 
air  has  been  used  for  therapeutical  piirposes,  but  in  doing  so  a  too  rapid  increase 
of  the  pressure  is  to  be  avoided.  Waldenburg  has  constructed  such  an  apparatus, 
which  may  be  used  for  the  respiration  of  air  under  a  greater  or  less  pressure. 


140.  Comparative  and  Historical. 

Mammals  have  lungs  similar  to  those  of  man.  The  lungs  of  birds  are  spongy, 
united  to  the  chest- wall,  and  there  are  openings  on  their  surface  communicating 
with  thin-walled  "  air-sacs"  which  are  placed  amongst  the  viscera.  The  air-sacs 
communicate  with  cavities  in  the  bones,  which  give  the  latter  great  lightness 
(Aristotle).  The  diaphragm  is  absent.  In  reptiles  the  lungs  are  divided  into 
greater  and  smaller  compartments  ;  in  snakes  one  lung  is  abortive,  while  the  other 
has  the  elongated  form  of  the  body.  The  amphibians  (frog)  possess  two  simple 
lungs,  each  of  which  represents  an  enormous  infundibulum  with  its  alveoli.  The 
frog  pumps  air  into  its  lungs  by  the  contraction  of  its  throat,  the  nostrils  beiuo- 
closed  and  the  glottis  opened.  When  young— until  their  metamorphosis — frogs 
breathe  like  fishes  by  means  of  gills.  The  perennibranchiate  amphibians  (Proteus), 
retain  their  gills  throughout  life.  Amongst  fishes,  which  breathe  by  gills  and 
use  the  O  absorbed  by  the  water,  the  Dipnoi  have  in  addition  to  gills  a  swim-bladder 
provided  with  afferent  and  efferent  vessels,  which  is  comparable  to  the  lung.  The 
Cobitis  respires  also  with  its  intestine  (Erman,  J  808).  Insects  and  centipedes 
respire  by  "  tracheae,"  which  are  branched  canals  distributed  throughout  the  body ; 
they  open  on  the  surface  of  the  body  by  openings  (stigmata)  which  can  be  closed. 
Spiders  respire  by  means  of  tracheae  and  tracheal  sacs,  crabs  by  gills.  The 
molluscs  and  cephalopoda  have  gills,  some  gasteropods  have  gills  and  others  lungs. 


278  HISTORICAL. 

Amongst  the  lower  invertebrata  some  breathe  by  gills,  others  by  means  of  a  special 
"  water- vascular  system,"  and  others  again  by  no  special  organs. 

Aristotle  (384  b.  c.  )  regarded  the  object  of  respiration  to  be  the  coohng  of  the 
body,  so  as  to  moderate  the  internal  warmth.  He  observed  correctly  that  the 
warmest  animals  breathe  most  actively,  but  in  interpreting  the  fact  he  reversed 
the  cause  and  effect.  Galen  (131-203  A.D.),  thought  that  the  "  soot"  was  removed 
from  the  body  along  with  the  expired  water.  The  most  important  experiments  on 
the  mechanics  of  respiration  date  from  Galen;  he  observed  that  the  lungs  passively 
follow  the  movements  of  the  chest;  that  the  diaphragm  is  the  most  important 
muscle  of  inspiration;  that  the  external  intercostals  are  inspiratory;  and  the  internal, 
expiratory.  He  divided  the  intercostal  nerves  and  muscles,  and  observed  that 
loss  of  voice  occurred.  On  dividing  the  spinal  cord  higher  and  higher,  he  found 
that  as  he  did  so,  the  muscles  of  the  thorax  lying  higher  up,  became  paralysed. 
Oribasius  (360  A.  D.)  observed  that  in  double  pneumothorax  both  lungs  collapsed. 
Vesalius  (1540)  first  described  artificial  respiration,  as  a  means  of  restoring  the 
beat  of  the  heart.  Malpighi  (1661)  described  the  structure  of  the  lungs.  J.  A. 
Borelli  (f  1679)  gave  the  first  fundamental  description  of  the  mechanism  of  the 
respiratory  movements.  The  chemical  processes  of  respiration  could  only  be  known 
after  the  discovery  of  the  individual  gases  therein  concerned.  Van  Helmont 
(+  1644)  detected  COg.  [Joseph  Black  (1757)  discovered,  by  the  following  experi- 
ment, that  CO2  or  "fixed  air  "is  given  out  during  expiration : — take  two  jars  of 
lime  water,  breathe  into  one  through  a  bent  glass  tube,  and  force  ordinary  air 
through  the  other,  when  a  white  precipitate  of  calcium  carbonate  will  be  found  to 
occur  in  the  former.]  In  1774  Priestley  discovered  0.  Lavoisier  detected  N  (1775), 
and  ascertained  the  composition  of  atmospheric  air,  and  he  regarded  the  formation 
of  CO2  and  H2O  of  the  breath  as  a  result  of  a  combustion  within  the  lungs 
themselves.  J.  Ingen-Houss  (1730-1790)  discovered  the  respiration  of  plants. 
Vogel  and  others  proved  the  existence  of  CO2  in  venous  blood,  and  Hoffmann  and 
others  that  of  0  in  arterial  blood.  The  more  complete  conception  of  the  exchange 
of  gases  was,  however,  only  possible  after  Magnus  had  extracted  and  analysed 
the  gases  of  arterial  and  venous  blood  (p.  55). 


Physiology  of  Digestion. 


141.  The  Mouth  and  its  Glands. 

The  mucous  membrane  of  the  cavity  of  the  mouth,  which  becomes  continuous 
with  the  skin  at  the  red  margin  of  the  lips,  has  a  number  of  sebaceoum  glands 
in  the  region  of  the  red  part  of  the  lip.  The  buccal  mucous  membrane  consists  of 
bundles  of  fine  fibrous  tissue  mixed  with  elastic  fibres,  which  traverse  it  in  every 
direction.  Papillce — simple  or  compound — occur  near  the  free  surfaces.  The 
sub-mucous  tissue,  which  is  directly  continuous  with  the  fibrous  tissue  of  the 
mucous  membrane  itself,  is  thickest  where  the  mucous  membrane  is  thickest,  and 
densest  where  it  is  firmly  fixed  to  the  periosteum  of  the  bone  and  to  the  gum  ;  it 
is  thinnest  where  the  mucous  membrane  is  most  movable,  and  where  there  are 
most  folds.  The  cavity  of  the  mouth  is  lined  by  stratified  squamous  epithelium 
(Fig.  115,  8),  which  is  thickest,  as  a  rule,  where  the  longest  papilla  occur. 

All  the  glands  of  the  mouth,  including  the  salivary  glands,  may  be 
divided  into  different  classes  according  to  the  nature  of  their  secretions. 

1.  The  serous  or  albuminous  glands  [true  salivary],  whose  secretion 
contains  a  certain  amount  of  albumin,  e.g.,  the  human  parotid. 

2.  The  mucous  glands,  whose  secretion  in  addition  to  some  albumin, 
contains  the  characteristic  constituent  mucin. 

3.  The  mixed  [or  muco-salivary]  glands,  some  of  the  acini  secreting 
albumin  and  others  mucin — e.g.,  the  human  maxillary  gland  (Heiden- 
hain).  The  structure  of  these  glands  is  referred  to  under  the  salivary 
glands. 

Numerous  muCOUS  glands  (labial,  buccal,  palatine,  lingual,  molar)  have  the 
appearance  of  small  macroscopic  bodies  lying  in  the  sub-mucosa.  They  are 
branched  tubular  glands,  and  the  contents  of  their  secretory  cells  consist  partly 
of  mucin,  which  is  expelled  from  them  during  secretion.  The  excretory  ducts  of 
these  glands,  which  are  lined  by  cylindrical  epithelium,  are  constricted  where 
they  enter  the  mouth.  Not  unfrequently  one  duct  receives  the  secretion  of  a 
neighbouring  gland. 

The  glands  of  the  tongue  form  two  groups,  which  differ  morphologically  and 
physiologically.  (1.)  The  muCOUS  glands  (Weber's  glands),  occurring  chiefly 
near  the  root  of  the  tongue,  are  branched  tubular  glands  lined  with  clear  trans- 
parent secretory  cells  whose  nuclei  are  placed  near  the  attached  end  of  the  cells. 
The  acini  have  a  distinct  membrana  propria.  (2.)  The  serOUS  glands  (Ebner's) 
are  acinous  glands  occurring  in  the  region  of  the  circumvallate  papillae  (and  in 
animals  near  the  papillas  foliatte).  They  are  lined  with  turbid  granular  epithelium 
with  a  central  nucleus,  and  they  secrete  saliva  (Henle).  (3.)  The  glands  of  Blandin 
and  Nuhn  are  placed  near  the  tip  of  the  tongue,  and  consist  of  mucous  and  serous 
acini,  so  that  they  are  mixed  glands  (Podwisotzky). 

The  blood-vessels  are  moderately  abundant,  and  the  larger  trunks  lie  in  the 


280  THE   SALIVARY  GLANDS. 

sub-mucosa,  whilst  the  finer  twigs  penetrate  into  the  papillte,  where  they  form 
pither  a  capillary  net-work  or  simple  loops. 

The  larger  lymphatics  lie  in  the  sub-mucosa,  whilst  the  finer  branches 
form  a  fine  net-work  placed  in  the  mucosa.  The  lymph-follicles  also  belong 
to  the  lymphatic  system.  On  the  dorsum  of  the  posterior  part  of  the  tongue  they 
form  an  almost  continuous  layer.  They  are  round  or  oval  (1-1  "5  mm.  in  diameter), 
and  placed  in  the  sub-mucosa.  They  consist  of  adenoid  tissue  loaded  with  lymph - 
corpuscles.  The  outer  part  of  the  adenoid  reticulum  is  compressed  so  as  to  form 
a  kind  of  capsule  for  each  follicle.  Similar  follicles  occur  in  the  intestine  as 
solitary  follicles,  in  the  small  intestine  they  are  collected  together  into  Peyer's 
patches,  and  in  the  spleen  they  occur  as  Malpighian  corpuscles.  On  the  dorsum 
of  the  tongue  several  of  these  follicles  form  a  slightly  oval  elevation,  which  is 
surrounded  by  connective  tissue.  In  the  centre  of  this  elevation  there  is  a  depres- 
sion into  which  a  mucous  gland  opens,  which  fills  the  small  crater  with  mucus. 

The  Tonsils  have  fundamentally  the  same  structure.  On  their  surface  are 
a  number  of  depressions  into  which  the  ducts  of  small  mucous  glands  open.  These 
depressions  are  surrounded  by  groups  (10-20)  of  lymph-follicles,  and  the  whole 
is  environed  by  a  capsule  of  connective  tissue.  After  E.  H.  Weber  discovered 
lymphatics  in  the  neighbourhood  of  the  tonsils,  Briicke  referred  these  structures  to 
the  lymphatic  system.  Large  lymph-spaces,  communicating  with  lymphatics,  occur 
in  the  neighbourhood  of  the  tonsils,  but  as  yet  a  direct  connection  between  the 
spaces  in  the  follicles  and  the  lymph-vessels  has  not  been  proved  to  exist. 
Stohr  found  that  numerous  leucocytes  passed  between  the  epithelium  covering 
the  tonsils,  and  reached  the  mouth. 

Nerves- — Numerous  medullated  nerve-fihres  occur  in  the  sub-mucosa,  pass  into 
the  mucosa  and  terminate  partly  in  the  individual  papillae  in  Krause's  End-bulbs, 
which  are  most  abundant  in  the  lips  and  soft  palate,  and  not  so  numerous  in  the 
cheeks  and  in  the  floor  of  the  mouth.  The  nerves  administer  not  only  to  common 
sensation,  but  they  also  are  the  organs  of  transmission  for  tactile  (heat  and  pres- 
sure) impressions.  It  is  highly  probable,  however,  that  some  nerve-fibres  end  in 
fine  terminal  fibrils,  between  the  epithelial  cells,  such  as  occur  in  the  cornea  and 
elsewhere. 

142.  The  Salivary  Glands. 

Structure  of  the  Ducts. — The  three  pairs  of  salivary  glands,  sub- 
maxillary, sub-lingual,  and  parotid,  are  compound  tubular  glands. 
Fig.  116,  A,  shows  a  fine  duct,  terminating  in  the  more  or  less  flask- 
shaped  alveoli  or  acini.  [Each  gland  consists  of  a  number  of  lobes, 
and  each  lobe  in  turn  of  a  number  of  lobules,  which,  again,  are 
composed  of  acini.  All  these  are  held  together  by  a  framework  of  con- 
nective tissue.  The  larger  branches  of  the  duct  lie  between  the  lobules, 
and  constitute  the  interlobular  ducts,  giving  branches  to  each  lobule  which 
they  enter,  constituting  the  intralobular  ducts.  These  intralobular  ducts 
branch  and  finally  terminate  in  connection  with  the  alveoli,  by  means 
of  an  intermediary  or  intercalary  part.  The  larger  interlobar  and  inter- 
lobular ducts  consist  of  a  membrana  propria,  strengthened  outside 
with  fibrous  and  elastic  tissue,  and  in  some  places  also  by  non-striped 
muscle,  while  the  ducts  are  lined  by  columnar  epithelial  cells.  In  the 
largest  branches,  there  is  a  second  row  of  smaller  cells,  lying  between 


THE   STRUCTURE   OF   THE   SALIVARY   GLANDS. 


281 


the  large  cells  and  the  membrana  propria.  The  intralobular  ducts  are 
lined  by  a  single  layer  of  large  cylindrical  epithelium.  As  is  shown  in 
Fig.  116,  E,  the  nucleus  occurs  about  the  middle  of  the  cell,  while  the 
outer  half,  i.e.,  next  the  basement  membrana  of  the  cell,  is  finely  striated 
longitudinally,  which  is  due  to  fibrillos ;  the  inner  half  next  the  lumen  is 
granular.  The  intermediary  part  is  narrow,  and  is  lined  with  a  single 
layer  of  flattened  cells,  each  with  an  elongated  oval  nucleus.  There  is 
usually  a  narrow  "  neck,"  where  the  intralobular  duct  becomes  continuous 
with  the  intermediary  part,  and  here  the  cells  are  polyhedral  (Klein). 

The  acini,  or  alveoli,  are  the  parts  where  the  actual  process  of  secretion 
takes  place.  They  vary  somewhat  in  shape — some  are  tubular,  others 
branched,  some  are  dilated  and  resemble  a  Florence  flask,  and  several 
of  them  usually  open  into  one  intermediary  part  of  a  duct.     Each 


Fi^.  116. 

A,  duct  ami  acini  of  the  parotid  gland  of  a  dog ;  B,  acini  of  the  sub-maxillary 
gland  of  a  dog  ;  c,  refractive  mucous  cells;  d,  granular  half-moons  of  Gianuzzi; 
C,  similar  alveoli  after  prolonged  secretion;  D,  basket-shaped  tissue  investment 
of  an  acinus;  E,  transverse  section  of  an  excretory  duct  lined  with  cylindrical 
"rodded"  epithelium;  F,  entrance  of  a  non-meduUated  nerve-fibre  into  a 
secretory  cell. 

alveolus  is  bounded  by  a  basement  membrane,  with  a  reticulate  structure 
made  up  of  nucleated,  branched  and  anastomosing  cells,  so  as  to  resemble 
a  basket   (D).      There   is   a  homogeneous  membrane   bounding   the 


282 


THE  STRUCrrRE  OF  THE  SALIVARY  GLANDS. 


The  flattened  nucleus  is 

acinus. 


alveoli  in  addition  to  this  basket-shaped  structure.  Immediately  out- 
side this  membrane  is  a  lymph-space  (Gianuzzi),  and  outside  this  again 
the  net-work  of  capillaries  is  distributed.  [The  extent  to  which  this 
lymph-space  is  filled  vith  lymph  determines  the  distance  of  the  capil- 
laries from  the  membrana  propria.  The  interalveolar  lymph-spaces 
communicate  with  large  lymph-spaces  between  the  lobules,  which  in 
turn  communicate  with  perivascular  lymphatics  around  the  arteries 
and  veins.]     The  lymphatics  emerge  from  the  gland  at  the  hilum. 

The  secretory  cells  vary  in  structure,  according  as  the  salivary  gland 
is  a  nmcoTis  [sub-maxillary  and  sub-lingual  of  the  dog  and  cat],  a 
serous  [parotid  of  man,  and  mammals,  and  sub-maxillary  of  rabbit], 
or  a  mixed  gland  [human  sub-maxillary  and  sub-lingual]. 

Mucous  Acini. — The  secretory  cells  of  mucous  glands,  and  the 
mucous  acini  of  mixed  glands  (Fig.  117),  are  lined  by  a  single 
layer  of  "mucin  cells"  (Heidenhain)  (Fig.  116,  B,  c),  which  are  large 
cells  distended  with  mucin,  or  at  least  with  a  hypothetical  sub- 
stance, mucigen,  which  yields  mucin.  The  mucin  cells  are  more 
or  less  spheroidal  in  shape,  clear,  shining,  highly  refractive,  and 
nearly  fill  the  acinus.     The  flattened  nucleus  is  near  the  wall  of  the 

Each  cell  has  a 
fine  process  which  over- 
laps the 'fixed  part  of  the 
cell  next  to  it.  Owing 
to  the  fact  that  the  body 
of  each  cell  is  infiltrated 
with  mucin,  these  cells  do 
not  stain  with  carmine, 
although  the  nucleus  and 
its  immediately  investing 
protoplasm  do.  Another 
kind  of  cell  occurs  in  the 
sub-maxillarj'  gland  of  the 
dog.  It  forms  a  half- 
■moon-shaped  structure 
(Gianuzzi)  lying  in  dfrect 
contact  with  the  wall  of 
the  acinus.  Each  "  half- 
moon  "  or  "  crescent "  con- 
sists of  a  number  of  small, 
closely  packed,  angular, 
strongly  albuminous  cells  with  small  oval  nuclei,  which,  however,  are 
separated  only  with  difficulty.  Hence,  Heidenhain  has  called  them 
"  crnnposUe  marginal  cells  "  (E,  d.)     They  are  granular,  darker,  devoid 


Fig.  117. 

part  of  the  hmnan  snb-maxillary 
On  the  left  of  the  figure  is  a  group 
of  serous  alveoli,  and  on  the  right  a  group 
of  mucous  alveoli. 


Section  of 
gland. 


HISTOLOGICAL  CHANGES   IN   THE  SALIVARY  GLANDS.  283 

of  mucin,  and  stain  readily  with  pigments.  [In  the  sub-maxillary 
gland  of  the  cat  there  is  a  complete  layer  of  these  "  marginal " 
carmine-staining  cells  lying  between  the  mucous  cells  and  the  mem- 
brana  propria.] 

[Serous  Acini. — In  true  serous  glands  (parotid  of  man  and  mammals) 
and  in  the  serous  acini  of  mixed  glands,  the  acini  are  lined  by  a  single 
layer  of  secretory  columnar  finely  granular  cells,  which  in  the  quiescent 
condition  completely  fill  the  acinus,  so  that  scarcely  any  lumen  is  left. 
Just  before  secretion,  or  when  these  cells  are  quiescent,  Langley  has 
shown  that  they  are  large  and  filled  with  numerous  granules,  which 
obscure  the  presence  of  the  nucleus.  As  secretion  takes  place,  these 
granules  seem  to  be  used  up  or  discharged  into  the  lumen;  at  least,  the 
outer  part  of  each  cell  gradually  becomes  clear  and  more  transparent, 
and  this  condition  spreads  towards  the  inner  part  of  the  cell.] 

[In  the  mixed  or  muco-sahvarj^  glands  (Klein),  (e.g.,  human  sub- 
maxillary), some  of  the  alveoli  are  mucous  and  others  serous  in  their 
cliaracters,  but  the  latter  are  always  far  more  numerous,  and  the  one 
kind  of  acinus  is  directly  continuous  with  the  others  (Fig.  117)]. 


143.   Histological  Changes  during  the  Activity  of 
the  Salivary  Glands. 

[The  condition  of  physiological  activity  of  the  gland-cells  is  accom- 
panied by  changes  in  the  histological  characters  of  the  secretory  cells.] 

[Serous  Glands. — The  changes  in  the  secretory  cells  have  been  care- 
fully studied  in  the  parotid  of  the  rabbit.  The  histological  appearances 
vary  somewhat,  according  as  the  glands  are  examined  in  the  fresh 
condition  or  after  hardening  in  various  reagents,  such  as  absolute 
alcohol.  When  the  gland  is  at  rod,  in  a  preparation  hardened  in 
alcohol,  and  stained  with  carmine,  the  cells  consist  of  a  pale,  almost 
uncoloured  substance,  with  a  few  fine  granules,  and  a  small  irregular 
red-stained,  shrivelled  nucleus,  devoid  of  a  nucleolus.  The  appearance 
of  the  nucleus  suggests  the  idea  of  its  being  shrivelled  by  the  action  of 
the  hardening  reagent  (Fig.  1 1 8)]. 

[During  activity,  if  the  gland  be  caused  to  secrete  by  stimulating 
the  sympathetic,  all  parts  of  the  cells  undergo  a  change  (Figs.  118,  119) 
(1)  The  cells  diminish  somcAvhat  in  size ;  (2)  the  nuclei  are  no  longer 
irregular,  but  round,  with  a  sharp  contour  and  nucleoli ;  (3)  the  sub- 
stance of  the  cell  itself  is  turbid,  owing  to  the  diminution  of  the  clear 
substance,  and  the  increase  of  the  granules,  especially  near  the  nuclei ; 
(4)  at  the  same  time,  the  whole  cell  stains  more  deeply  with  carmine 
(Heidenhain). 


284 


HISTOLOGICAL   CHANGES   IN   THE   SALIVARY   GLANDS. 


On  studying  the  changes  which  occur  in  a  living  serous  gland,  Langley 
found  that,  during  rest,  the  substance  of  the  cells  of  the  parotid  is  per- 
vaded by  fine  granules,  which  are  so  numerous  as  to  obscure  the  nucleus, 
while  the  outlines  of  the  cells  are  indistinct.  No  lumen  is  visible  in 
the  acini  during  activity,  the  granules  disappear  from  the  outer  zone  of 
the  cells,  the  cells  themselves  becoming  more  distinct  and  smaller.    After 


Fk.  118. 


Fig.  119. 


Sections  of  a  "  serous  "  gland— the  parotid  of  a  rabbit,  Fig.  118,  at  rest ;  Fig.  1 19, 
after  stimulation  of  the  cervical  sympathetic. 

prolonged  secretion,  the  granules  largely  disappear  from  the  cell-substance 
except  quite  near  the  inner  margin.  The  cells  are  smaller,  their  outlines 
more  distinct,  their  round  nuclei  apparent,  and  the  lumen  of  the  acini 
is  wide  and  distinct.  Thus,  it  is  evident  that,  during  rest,  granules  are 
manufactured,  which  disappear  during  the  activity  of  the  cells,  the  dis- 
appearance taking  place  from  without  inwards.  Similar  changes  occur 
in  the  cells  of  the  pancreas.] 

[Mucous  Glands. — More  complex  changes  occur  in  the  mucous  glands, 
such  as  the  sub-maxillary  or  orbital  glands  of  the  dog  (Lavdovsky). 
The  appearances  vary  according  to  the  intensity  and  duration  of  the 
secretory  activity. 

The  mucous  cells  at  rest  are  large,  clear,  and  refractive,  containing  a 
flattened  nucleus  (Fig.  116,  B,  c),  surrounded  with  a  small  amount  of 
protoplasm,  and  placed  near  the  basement  membrane.  The  clear  sub- 
stance does  not  stain  with  carmine,  and  consists  of  mucigen  lying  in  the 
wide  spaces  of  an  intracellular  plexus  of  fibrils.  After  prolonged  secretion, 
produced,  it  may  be,  by  strong  and  continued  stimulation  of  the  chorda, 
the  mucous  cells  of  the  sub-maxillary  gland  of  the  dog  undergo  a  great 
change.]  The  distended,  refractive,  and  "  mucous-cells,"  which  occur  in 
the  quiescent  gland,  and  which  do  not  stain  with  carmine,  do  not  appear 
after  the  gland  has  been  in  a  state  of  activity.  Their  place  is  taken  by 
small  dark  protoplasmic  cells  (Fig.  116,  C),  devoid  of  mucin.    These  cells 


THE  NERVES  OF  THE  SALIVARY  GLANDS.         285 

readily  stain  with  carmine,  whilst  their  nucleus  is  scarcely,  if  at  all, 
coloured  by  the  dye.  The  researches  of  R.  Heidenhain  (1868)  have 
shed  much  light  on  the  secretory  activity  of  the  salivary  glands. 

The  chanore  may  be  produced  in  two  ways.  Either  it  is  due  to  the  "mucous  cells  " 
during  secretion  becoming  broken  up,  so  that  they  yield  their  mucin  directly  to  the 
saliva ;  in  saliva  rich  in  mucin,  small  microscopic  pieces  of  mucin  are  found,  and 
sometimes  mucous  cells  themselves  are  present.  Or,  we  must  assume  that  the 
mucous  cells  simply  eliminate  the  mucin  from  their  bodies  (Ewald,  Stiihr);  while, 
after  a  period  of  rest,  new  mucin  is  formed.  According  to  this  view,  the  dark 
granular  cells  of  the  glands,  after  active  secretion,  are  simply  mucous  cells,  which 
have  given  out  their  mucin.  If  we  assume,  with  Heidenhain,  that  the  mucous 
cells  break  up,  then  these  granular  non-mucous  cells  must  be  regarded  as  new 
formations  produced  by  the  proliferation  and  growth  of  the  composite  marginal  cells, 
i.e.,  the  cresceots,  or  half-moons  of  Gianuzzi. 

[During  rest,  the  protoplasm  seems  to  manufacture  mucigen,  which  is 
changed  into  and  discharged  as  mucin  in  the  secretion,  when  the  gland 
is  actively  secreting.  Thus,  the  cells  become  smaller,  but  the  proto- 
plasm of  the  cell  seems  to  increase,  new  mucigen  is  manufactured  during 
rest,  and  the  cycle  is  repeated.] 

144.  The  Nerves  of  the  Salivary  Glands. 

The  nerves  are  for  the  most  part  medullated,  and  enter  at  the  hilum 
of  the  gland,  where  they  form  a  rich  plexus  provided  with  ganglia 
between  the  lobules.  [According  to  Klein,  there  are  no  ganglia  in  the 
parotid  gland.] 

All  the  salivary  glands  are  supplied  by  branches  from  two  different 
nerves — from  the  sympathetic  and  from  a  cranial  nerve. 

1.  The  sympathetic  nerve  gives  branches  to  (a.)  the  sub-maxillary 
and  the  sub- lingual  glands,  derived  from  the  plexus  on  the  external 
maxillary  artery ;  (b.)  to  the  parotid  gland  from  the  carotid  plexus. 

2.  The  facial  nerve  gives  branches  to  the  sub-maxillary  and 
sub-lingual  glands  from  the  chorda  tympani  Avhich  accompanies  the 
lingual  branch  of  the  fifth  nerve.  The  branches  to  the  parotid 
reach  it  in  a  roundabout  way.  They  arise  from  the  tympanic  branch 
of  the  glosso-pharyngeal  nerve  (dog).  The  tympanic  plexus  sends 
fibres  to  the  small  superficial  petrosal  nerve  (Eckhard,  Loeb,  Heiden- 
hain), and  with  it  these  fibres  run  to  the  anterior  surface  of  the 
pyramid  in  the  temporal  bone,  and,  after  passing  through  the  fora- 
men lacerum  anticum,  reach  the  otic  ganglion.  This  ganglion  sends 
branches  to  the  auriculo-temporal  nerve  (itself  derived  from  the  third 
branch  of  the  trigeminus),  which,  as  it  passes  upwards  to  the  tem- 
poral region  under  cover  of  the  parotid,  gives  branches  to  this  gland 
(v.  Wittich). 

The   sub-maxillary   ganglion,   which   gives   branches   to   the   sub- 


286     ACTION  OF  NERVES  ON  THE  SECRETION  OF  SALIVA. 

maxillary  and  sub-lingual  glands,  receives  fibres  from  the  tympanico- 
lingual  nerve,  as  well  as  sympathetic  fibres  from  the  plexus  on  the 
external  maxillary  artery. 

Termination  of  the  nerve-fibres. — With  regard  to  the  ultimate 
distribution  of  these  nerves  we  can  distinguish  (1)  the  vaso-motor  nerves, 
which  give  branches  to  the  walls  of  the  blood-vessels;  and  (2)  the  secretory 
nerves  proper.  Pfliiger  states,  with  regard  to  the  latter,  that  (a.) 
medullated  nerve-fibres  penetrate  the  acini ;  the  sheath  of  Schwann 
(gray  sheath)  unites  with  the  membrana  propria  of  the  acinus ;  the 
medullated  fibre — still  medullated — passes  between  the  secretory  cells, 
where  it  divides  and  becomes  non-medullated,  and  its  axial  cylinder 
terminates  in  connection  with"' the  nucleus  of  a  secretory  cell.  [This, 
however,  is  not  proved]  (Fig.  116,  F). 

(b)  According  to  Pfliiger,  some  of  the  nerve-fibres  end  in  multipolar  ganglion  cells, 
which  lie  outside  the  wall  of  the  acinus,  and  these  cells  send  branches  to  the 
secretory  cells  of  the  acini.  [These  cells  probably  correspond  to  the  branched  cells 
of  the  basket-shaped  structure.] 

(c)  Again,  he  describes  medullated  fibres  which  enter  the  attached  end  of  the 
cylindrical  epithelium  lining  the  excretory  ducts  of  the  glands  (E).  Pfliiger  thinks 
that  those  fibres  enteriag  the  acini  directly  are  cerebral,  while  those  with  ganglia 
in  their  course  are  derived  from  the  sympathetic  system. 

[{(l)  The  du-ect  termination  of  nerve-fibres  has  been  observed  in  the  salivary 
glands  of  the  cockroach  by  Kupffer.] 


145.  Action  of  the  Nervous  System  on  the 
Secretion  of  Saliva. 

A.  Sub-maxillary  Gland. — Stimulation  of  the  facial  nerve  at  its 
origin  (Ludwig  and  Eahn)  causes  a  profuse  secretion  of  a  thin 
watery  saliva,  which  contains  a  very  small  amount  of  specific  consti- 
tuents  (Eckhard).  Simultaneously  with  the  act  of  secretion,  the  blood- 
vessels of  the  glands  become  dilated,  and  the  capillaries  are  so  distended 
that  the  pulsatile  movement  in  the  arteries  is  propagated  into  the 
veins.  Nearly  four  times  as  much  blood  flows  out  of  the  veins  (01. 
Bernard),  the  blood  being  of  a  bright  red  colour,  and  contains  one- 
third  more  0  than  the  venous  blood  of  the  non-stimulated  gland. 
Notwithstanding  this  relatively  high  percentage  of  0,  the  secreting 
gland  uses  more  0  than  the  passive  gland  (§  131,  1). 

[If  a  cannula  be  placed  in  Wharton's  duct,  e.g.,  in  a  dog,  and  the 
chorda  tympani  be  divided,  no  secretion  flows  from  the  cannula.  On 
stimulating  the  x^erii^heral  end  of  the  chorda  tynvpani  with  an  interrupted 
current  of  electricity,  the  same  results — copious  secretion  of  saliva  and 
vascular  dilatation,  with  increased  flow  of  blood  through  the  gland — 


ACTION  OF  NERVES  ON  THE  SECRETION  OF  SALIVA.     287 

occur,  as  when  the  origin  of  the  seventh  nerve  itself  is  stimulated.  The 
watery  saliva  is  called  chorda  saliva.] 

Two  functionally  different  kinds  of  nerve-fibres  occur  in  the  facial 
nerve — (1)  True  secretory  fibres,  (2)  vaso-dilator  fibres.  The  increased 
amount  of  secretion  is  not  due  simply  to  the  increased  blood  supply. 

II.  Stimulation  of  the  sympathetic  nerve  causes  a  scanty  amount 
of  a  very  thick,  sticky,  mucous  secretion  (Eckhard),  in  which  the 
specific  salivary  constituents,  mucin,  and  the  salivary  corpuscles  are 
very  abundant.  The  specific  gravity  of  the  saliva  is  raised  from  1,007 
to  1,010.  Simultaneously  the  blood-vessels  become  contracted,  so  that 
tile  blood  flows  more  slowly  from  the  veins,  and  has  a  dark  bluish 
colour. 

The  sympathetic  also  contains  two  kinds  of  nerve-fibres — (1)  True 
secretory  fibres,  and  (2)  vaso-constrictor  fibres. 

Relation  to  Stimulus.— On  stimulating  the  cerebral  nerves, at  first  with  a  weak 
and  gradually  with  a  stronger  stimulus,  there  is  a  gradual  development  of  the 
secretion  in  which  the  solid  constituents— occasionally  the  organic— are  increased 
(Heidenhain).  If  a  strong  stimulus  be  api)lied  for  a  long  time,  the  secretion 
diminishes,  becomes  watery,  and  is  poor  in  specific  constituents,  especially  in  the 
organic  elements,  which  are  more  affected  than  the  inorganic  (C.  Ludwig  and 
Becher).  After  prolonged  stimulation  of  the  sympathetic,  the  secretion  resembles  the 
chorda  saliva.  It  would  seem,  therefore,  that  the  chorda  and  sympathetic  saliva 
are  not  specifically  distinct,  but  vary  only  in  degree.  On  continuing  the  stimula- 
tion of  the  nerves  up  to  a  certain  maximal  limit,  the  rajiidity  of  secretion  becomes 
greater,  and  the  percentage  of  salts  also  increases  to  a  certain  maximum,  and  this 
independently  of  the  former  condition  of  the  glands.  The  percentage  of  organic 
constituents  also  depends  on  the  strength  of  the  nervous  stimulation,  but  not  on  this 
alone,  as  it  is  essentially  contingent  upon  the  condition  of  the  gland  before  the 
secretion  took  place,  and  it  also  depends  upon  the  duration  and  intensity  of  the 
previous  secretory  activity.  Very  strong  stimulation  of  the  gland  leaves  an 
"after-effect"  which  predisposes  it  to  give  off  organic  constituents  into  the 
secretion  (Heidenhain). 

Relation  to  Blood  Supply. — The  secretion  of  saliva  is  not  simply  the 
result  of  the  amount  of  blood  in  the  glands ;  that  there  is  a  factor 
independent  of  the  changes  in  the  state  of  the  vessels  is  shown  by  the 
following  facts  : — 

(1.)  The  secretory  activity  of  the  glands  when  their  nerves  are  stimulated  con- 
tinues for  some  time  after  the  blood-vessels  of  the  gland  have  been  ligatured 
(Ludwig,  Czermack).  [If  the  head  of  a  rabbit  be  cut  off,  stimulation  of  the  seventh 
nerve,  above  where  the  chorda  leaves  it,  causes  a  flow  of  saliva  which  cannot  be 
accounted  for  on  the  supposition  that  the  saliva  already  present  in  the  salivary 
glands  is  forced  out  of  them.  Thus  we  may  have  secretion  without  a  blood-stream. 
The  saliva  is  really  secreted  from  the  lymph  present  in  lymph-spaces  of  the  gland 
(Ludwig)]. 

(2.)  Atrop'm  and  Daturln  extinguish  the  activity  of  the  secretory  fibres  in  the 
chorda  tympaui,  but  do  not  affect  the  vaso-dilator  fibres  (Heidenhain).  The 
same  results  occur  after  the  iujection  of  acids  and  alkalies  iuto  the  excretory 
duct  (Gianuzzi). 


288  ACTION   OF  NERVES  ON   THE  SECRETION  OF   SALIVA. 

(3.)  The  pressure  in  the  excretory  duct  of  the  salivary  gland — measured  by 
means  of  a  manometer  tied  into  it — may  be  nearly  twice  as  great  as  the  pressure 
within  the  arteries  of  the  glands  (Ludwig),  or  even  in  the  carotid  itself.  The 
pressure  in  Wharton's  duct  may  reach  200  mm.  Hg. 

(4.)  Just  as  in  the  case  of  muscles  and  nerves,  the  salivary  glands  become /a%«e(Z 
or  exhausted  after  prolonged  action.  This  result  may  also  be  brought  about  by  in- 
jecting acids  or  alkalies  into  the  duct,  which  shows  that  the  secretory  activity  of  the 
gland  is  independent  of  the  circulation  (Gianuzzi). 

[The  vascular  dilatation  and  the  increased  flow  of  saliva  due  to  the 
activity  of  the  secretory  cells,  produced  by  stimulation  of  the  chorda 
tympani,  although  they  occur  simultaneously,  do  not  stand  in  the  rela- 
tion of  cause  and  eff"ect.  We  may  cause  vascular  dilatation  without  an 
increased  flow  of  saliva,  as  already  stated  (2).  If  atropin  be  given  to 
an  animal,  stimulation  of  the  chorda  produces  dilatation  of  the  blood- 
vessels, but  no  secretion  of  saliva.  Atropin  paralyses  the  secretory 
fibres,  but  not  the  vaso-dilator  fibres  (Fig.  120).  The  increased  supply 
of  blood,  while  not  causing,  yet  favours  the  act  of  secretion,  by  placing 
a  larger  amount  of  pabulum  at  the  disposal  of  the  secretory  elements, 
the  cells.] 

[The  experiment  described  under  (3.)  proves,  in  a  definite  manner, 
that  the  passage  of  the  water  from  the  blood-vessels,  or  at  least  from 
the  lymph  into  the  acini  of  the  gland,  cannot  be  due  to  the  blood- 
pressure;  that,  in  fact,  it  is  not  a  mere  process  of  filtration,  such  as 
occurs  in  the  glomeruli  of  the  kidney.  In  the  case  of  the  salivary  gland, 
where  the  pressure  within  the  gland  may  be  double  that  of  the  arterial 
pressure,  the  water  actually  moves  from  the  lymph  against  very  great 
resistance.  We  can  only  account  for  this  result  by  ascribing  it  to  the 
secretory  activity  of  the  gland-cells  themselves.  Whether  the  activities 
of  the  gland-cells,  as  suggested  by  Heidenhain,  are  governed  directly 
by  two  distinct  kinds  of  nerve-fibres,  a  set  of  solid-secreting  fibres,  and 
a  set  of  water-secreting  fibres,  remains  to  be  proved.] 

All  these  facts  lead  us  to  conclude  that  the  nerves  exercise  a  direct  effect  upon 
the  secretory  cells,  apart  from  their  action  on  the  blood-vessels.  This  physiological 
consideration  goes  hand  in  hand  with  the  anatomical  fact  of  the  direct  continuation 
of  nerve-fibres  with  the  secretory  cells.  When  the  chorda  tympani  is  extirpated 
on  one  side  in  young  dogs,  the  sub-maxillary  gland  on  that  side  does  not  develop 
so  much — its  weight  is  50  per  cent.  less — while  the  mucous  cells  and  the  ' '  crescents" 
are  smaller  than  on  the  sound  side  (Bufalini). 

During  secretion,  the  temperature  of  the  gland  rises  1'5°C  (Ludwig), 
and  the  blood  flowing  from  the  veins  is  often  warmer  than  the  arterial 
blood. 

"Paralytic  Secretion"  of  Saliva. — By  this  term  is  meant  the  continued 
secretion  of  a  thin  watery  saliva  from  the  sub-maxillary  gland,  which 
occurs  24  hours  after  the  secretion  of  the  cerebral  weri^es  (chorda  of  the 
seventh),  i.e.,  those  branches  of  them  that  go  to  this  gland,  whether  the 


REFLEX   SECRETION   OF   SALIVA. 


289 


sympathetic  be  divided  or  not  (CI.  Bernard).  It  increases  until  the 
eighth  day,  after  which  it  gradually  diminishes,  while  the  gland  tissue 
degenerates.  The  injection  of  a  small  quantity  of  curara  into  the  artery 
of  the  gland  also  causes  it.  Perhaps  it  arises  from  the  secretion,  which 
stagnates  within  the  gland  after  section  of  the  nerves,  acting  as  a  direct 
stimulus  to  secretion  (Heidenhain).  Perhaps  it  may  be  explained  as  a 
degeneration  effect,  comparable  to  the  fibrillar  contractions  which  occur 
in  a  muscle  after  secretion  of  its  motor  nerve. 

B.  Sub-lingual  Gland. — Very  probably  the  same  relations  obtain  as 
in  the  sub-maxillary  gland. 

C.  Parotid  Gland. — In  the  dog,  stimulation  of  the  sympathetic  alone, 
causes  no  secretion ;  it  occurs  when  the  glosso-pharyngeal  branch  to  the 
parotid  is  simultaneously  excited.  This  branch  may  be  reached  within 
the  tympanum  in  the  tympanic  plexus.  A  thick  secretion  containing  much 
organic  matter  is  thereby  obtained.  Stimulation  of  the  cerebral  branch 
alone  yields  a  clear  thin  watery  secretion,  containing  a  very  small  amount 
of  organic  substances,  but  a  considerable  amount  of  the  salts  of  the 
saliva  (Heidenhain). 

Reflex  Secretion  of  Saliva. — [If  a  cannula  be  placed  in  Wharton's 
duct,  e.g.,  in  a  dog,  during  fasting,  no  saliva  will  flow  out.  If  the  mu- 
cous membrane  of  the  mouth  be  stimulated  by  a  sapid  substance  placed 
on  the  tongue,  there  is  a  copious  flow  of  saliva.  If  the  sympathetic 
nerve  be  divided,  secre- 
tion still  takes  place  when 
the  mouth  is  stimulated, 
but  if  the  chorda  tympani 
be  cut,  secretion  no  longer 
takes  place.  Hence,  the 
secretion  is  a  reflex  act ; 
in  this  case,  the  lingual 
is  the  afferent,  and  the 
chorda  the  nerve-carry- 
ing impulses  from  a 
centre  situated  in  the 
medulla  oblongata  (Fig. 
120).]  Inthe  intact  body, 
the  secretion  of  saliva 
occurs  through  a  reflex  stimulation  of  the  nerves  concerned,  whereby 
under  normal  circumstances  the  secretion  is  always  watery  (chorda  or 
facial  saliva).  The  centripetal  or  afferent  nerve-fibres  concerned  are: — 
(1)  The  nerves  of  taste.  (2)  The  sensory  branches  of  the  trigeminus 
of  the  entire  cavity  of  the  mouth  and  the  glosso-pharyngeal  (which 
appear  to  be  capable  of  being  stimulated  by  mechanical  stimuli,  pressure, 

19 


VksseiajeP  Gi  mno 


Diagram  of  a  salivary  gland. 


290  REFLEX    SECRETION    OF    SALIVA, 

tension,  displacement).  The  movements  of  mastication  also  cause  a 
secretion  of  saliva.  Pfliiger  found  that  one-third  more  saliva  was 
secreted  on  the  side  where  mastication  took  place;  and  CI.  Bernard 
observed  that  the  secretion  ceased  in  horses  during  the  act  of  drinking. 
(3)  The  nerves  of  smell,  excited  by  certain  odours.  (4)  The  gastric 
branches  of  the  vagus  (Frerichs,  Oehl).  A  rush  of  saliva  into  the  mouth 
usually  precedes  the  act  of  vomiting  (p.  310). 

(5)  The  stimulation  of  distant  sensory  nerves,  e.g.,  the  central  end  of  the  sciatic 
— certainly  through  a  complicated  reflex  mechanism — causes  a  secretion  of  saliva 
(Owsjannikow  and  Tschierjew).  Perhaps  the  secretion  of  saliva,  which  sometimes 
occurs  during  pregnancy,  is  caused  in  the  same  reflex  manner. 

Stimulation  of  the  conjunctiva,  e.g.,  by  applying  an  irritating  fluid 
to  the  eye  of  carnivorous  animals,  causes  a  reflex  secretion  of  saliva 
(Aschanbrandt) . 

The  reflex  centre  for  the  secretion  of  saliva  lies  in  the  medulla 
oblongata,  at  the  origin  of  the  seventh  and  ninth  cranial  nerves  (Eckhard, 
Loeb).  The  centre  for  the  sympathetic  fibres  is  also  placed  here 
(Grriitzner  and  Chlapowski).  This  region  is  connected  by  nerve-fibres 
with  the  cerebrum;  hence,  the  thought  of  a  savory  morsel,  some- 
times when  one  is  hungry,  causes  a  rapid  secretion  of  a  thin  watery 
fluid — [or,  as  we  say,  "  makes  the  mouth  water  "].  If  the  centre  be 
stimulated  directly  by  a  mechanical  stimulus  (puncture),  salivation 
occurs,  while  asphyxia  has  the  same  efi'ect.  The  reflex  secretion  of  saliva 
may  be  inhibited  by  stimulation  of  certain  sensory  nerves,  e.g.,  by  pulling 
out  a  loop  of  the  intestine  (Pawlow).  Stimulation  of  the  cortex  cerebri 
of  a  dog,  near  the  sulcus  cruciatus,  is  often  followed  by  secretion  of 
saliva  (Eulenberg  and  Landois,  Bochefontaine,  BubnofF,  and  Heidenhain). 
Disease  of  the  brain  in  man  sometimes  causes  a  secretion  of  saliva,  owing 
to  the  efi'ects  produced  on  the  intracranial  centre. 

So  long  as  there  is  no  stimulation  of  the  nerves,  there  is  no  secretion 
of  saliva,  as  in  sleep  (Mitscherhch).  Directly  after  the  section  of  all  the 
nerves,  secretion  stops,  for  a  time  at  least. 

Pathological  Conditions  and  Poisons. — Certain  affections,  as  inflammation 

of  the  mouth,  neuralgia,  ulcers  of  the  mucous  membrane,  affections  of  the  gums, 
due  to  teething  or  the  prolonged  administration  of  mercury,  often  produce  a  copious 
secretion  oi  saMva,  (or  ptyalism).  Certain  poisons  cause  the  same  effect  by  direct 
stimulation  of  the  nerves,  as  Calabar  bean  (Physostigmin),  digitalin,  and  esj)ecially 
pilocarpin.  Many  poisons,  especially  the  narcotics — above  all,  atropin — paralyse 
the  secretory  nerves,  so  that  there  is  a  cessation  of  the  secretion,  and  the 
mouth  becomes  dry ;  while  the  administration  of  muscarin  in  this  condition  causes 
secretion  (Prevost).  Pilocarpin  acts  on  the  chorda  tympani,  causing  a  profuse 
secretion,  and,  if  atropin  be  given,  the  secretion  is  again  arrested.  Conversely,  if  the 
secretion  be  arrested  Ijy  atropin,  it  may  be  restored  by  the  action  of  pilocarpin  or 
physostigmin.  Nicotin,  in  small  does,  excites  the  secretory  nerves,  but  in  large  doses 
paralyses  them  (Heidenhain).  Daturin,  cicutin,  and  iodide  of  tethylstrychnine, 
paralyse  the  chorda. 


THE   PAROTID   SALIVA.  291 

Theory  of  Salivary  Secretion.— Heidenhain  has  recently  formulated  the 
following  theory  regarding  the  secretion  of  saliva  :— "  During  the  passive  or  qitiea- 
cent  condition  of  the  gland,  the  organic  materials  of  the  secretion  are  formed  from 
and  by  the  activity  of  the  protoplasm  of  the  secretory  cells.  A  quiescent  cell,  which 
has  been  inactive  for  some  time,  therefore  contains  little  protoplasm,  and  a  large 
amount  of  these  secretory  substances.  In  an  actively  secreting  gland,  there  are 
two  processes  occurring  together,  but  independent  of  each  other,  and 
regulated  by  two  different  classes  of  nerve-fibres ;  secretory  fibres  cause 
the  act  of  secretion,  while  trojjhic  fibres  cause  chemical  processes  within  the 
cells,  partly  resulting  in  the  formation  of  the  soluble  constituents  of  the  secre- 
tion, and  partly  in  growth  of  the  protoplasm.  According  to  the  number  of 
both  kinds  of  fibres  present  in  a  nerve  passing  to  a  gland,  such  nerve  being 
stimulated,  the  secretion  takes  place  more  rapidly  (cerebral  nerve)  or  more 
slowly  (sympathetic),  while  the  secretion  contains  less  or  more  solid  constituents. 
The  cerebral  nerves  contain  many  secretory  fibres  and  few  trophic  fibres,  while 
the  sympathetic  contains  many  trophic,  but  few  secretory  fibres.  The  rapidity 
and  chemical  composition  of  the  secretion  vary,  according  to  the  strength  of  the 
stimulus.  During  continued  secretion,  the  supply  of  secretory  materials  in  the 
gland-cells  is  used  up  more  rapidly  than  it  is  replaced  by  the  activity  of  the  pro- 
toplasm ;  hence,  the  amount  of  organic  constituents  diminishes,  and  the  micro- 
scopic characters  of  the  cells  are  altered.  The  microscopic  characters  of  the  cells 
are  altered  also  by  the  increase  of  the  protoplasm,  which  takes  place  in  an  active 
gland.  The  mucous  cells  disappear,  and  seem  to  be  dissolved  after  prolonged 
secretion,  and  their  place  is  taken  by  other  cells  derived  from  the  proliferation  of 
the  marginal  cells.  The  energy  which  causes  the  current  of  fluid  depends  upon 
the  protoplasm  of  the  gland-cells." 

The  saliva  is  diminished  in  amount  in  man  in  cases  of  paralysis  of  the  facial 
or  sympathetic  nerves,  as  is  observed  in  unilateral  paralysis  of  these  nerves. 

146.  The  Saliva  of  the  Individual  Glands. 

(a.)  The  Parotid  Saliva  is  obtained  by  placing  a  fine  cannula  in 
Steno's  duct  (Eckhard) ;  it  has  an  alkaline  reaction,  but  during  fasting, 
the  first  few  drops  may  be  neutral  or  even  acid  on  account  of  free 
CO2  (Oehl) — its  specific  gravity  is  1,003  to  1,004.  When  allowed  to 
stand  it  becomes  turbid,  and  deposits,  in  addition  to  albuminous 
matter,  calcium  carbonate,  which  is  present  in  the  fresh  saliva  in  the 
form  of  bicarbonate. 

Salivary  calculi  are  formed  in  the  ducts  of  the  salivary  glands,  owing  to  the 
deposition  of  lime  salts,  and  they  contain  only  traces  of  the  other  salivary  con- 
stituents ;  in  the  same  way  is  formed  the  tartar  of  the  teeth,  which  contains  many 
threads  of  leptothrix,  and  the  remains  of  low  organisms  which  live  in  decom- 
posing saliva  in  carious  cavities  between  the  teeth. 

It  contains  small  quantities  (more  abundant  in  the  horse)  of  a 
globulin-like  body,  and  never  seems  to  be  without  CNKS  sulpho- 
cyanide  of  potassium  (or  sodium — Treviranus,  1814),  which,  however, 
is  absent  in  the  sheep  and  dog  (Brettel). 

The  sulphocyanide  gives  a  dark  red  colour  (ferric  sulphocyanide)  with  ferric 
chloride.  It  also  reduces  iodic  acid  when  added  to  saliva,  causing  a  yellow  colour 
from  the  liberation  of  iodine,  which  may  be  detected  at  once  by  starch  (Solera), 


292  THE  MIXED   SALIVA  IN   THE  MOUTH. 

Mucin  is  absent,  hence  the  parotid  saliva  is  fluid,  is  not  sticky, 
and  can  readily  be  poured  from  one  vessel  into  another.  It  contains 
1'5-1'6  per  cent,  of  solids  (Mitscherlich,  van  Setten)  in  man,  of  which 
0"3-l"0  per  cent,  is  inorganic. 

Amongst  the  organic  substances  the  most  important  are  Ptyalin,  a  small 
amount  of  urea  (Gobley),  and  traces  of  a  volatile  acid  (Caproic  1) 

Of  the  inorganic  constituents — the  most  abundant  are  potassium  and  sodium 
chlorides ;  then  potassium,  sodium,  and  calcium  carbonates,  some  phosphates 
and  a  trace  of  an  alkaline  sulphate. 

(h.)  The  Sub -maxillary  Saliva  is  obtained  by  placing  a  cannula  in 
Wharton's  duct;  it  is  alkaline,  and  may  be  strongly  so.  When  allowed 
to  stand  for  a  long  time,  fine  crystals  of  calcium  carbonate  are  deposited, 
together  with  an  amorphous  albuminous  body.  It  always  contains 
mucin  (which  is  precipitated  by  acetic  acid) ;  hence,  it  is  usually  some- 
what tenacious.  Farther,  it  contains  ptyalin,  but  in  less  amount  than  in 
parotid  saliva;  and,  according  to  Oehl,  only  0*0036  per  cent,  of  potassium 
sulphocyanide. 

Chemical  Composition.— Sub-maxillary  saliva  (dog) : 
Water,       ....     991-45  per  1,000, 
Organic  Matter,  ,        .        2*89  ,,       ,, 

(  4-50  NaCl  and  CaClg. 
Inorganic  Matter,       .        .        5'66<   1'16     CaCOs,    Calcium    and    Magnesium 

(  phosphates. 

Pfliiger  found  that  100  cubic  centimetres  of  the  saliva  contained  0*6  O — 64 '7  COg 
(part  could  be  pumped  out,  and  part  required  the  addition  of  phosphoric  acid); 
0-8  N.;  or,  in  100  vol.  gas,  0.91  0  ;  97-88  CO2,  1-21  N. 

(c.)  The  Sub-lingual  Saliva  is  obtained  by  placing  a  very  fine  cannula 
in  the  ductus  Rivinianus  (Oehl),  is  strongly  alkaline  in  reaction,  very 
sticky  and  cohesive,  contains  much  mucin,  numerous  salivary  corpuscles, 
and  some  potassium  sulphocyanide  (Louget). 

147.  The  Mixed  Saliva  in  the  Mouth. 

The  fluid  in  the  mouth  is  a  mixture  of  the  secretions  from  the 
salivary  glands,  and  the  secretions  of  the  mucous  glands  of  the  mouth. 

(1.)  Physical  Characters. — The  mixed  saliva  of  the  mouth  is  a  some- 
what opalescent,  tasteless,  odourless,  slightly  glairy,  fluid,  with  a  specific 
gravity  of  1,004-1,009,  and  an  alkaline  reaction.  The  amount  secreted 
in  24  hours=200  to  1,500  grammes  (7-70  oz);  according  to  Bidder 
and  Schmidt,  however,  1,000  to  2,000  grammes.  The  solid  con- 
stituents =5*8  per  1,000. 

Composition. — The  solids  are  :— Epithelium  and  mucus,  2-2  ;  ptyalin  and 
albumin,  1*4  ;  salts,  2-2  ;  potassium  sulphocyanide,  0-04  per  1,000.  The  ash  con- 
tains chiefly  potash,  phosphoric  acid,  and  chlorine  (Hammerbacher). 

Decomposition  products  of  epithelium,  salivary  corpuscles,  or  the  remains  of  food, 


THE   MIXED   SALIVA    IN    THE   MOUTH.  293 

may  render  it  acid  temporarilij,  as  after  long  fasting,  and  after  much  speaking 
(Hoppe-Seylcr),  Even  outside  the  body,  saliva  containing  much  epithelium 
becomes  acid  before  it  putrifies  (Gorup-Besanez).  The  reaction  is  acid  in  some 
cases  of  dyspepsia  and  in  fever,  owing  to  the  stagnation  and  insufficient  secretion. 

(2.)  Microscopic  Constituents. — {a)  The  salivary  corpuscles  are  slightly- 
larger  than  the  white  blood-corpuscles  (8-1 1  fx),  and  are  nucleated  pro- 
toplasmic globular  cells  without  an  envelope.  During  their  living 
condition,  the  particles  in  their  interior  exhibit  molecular  or  Brownian 
movement.  The  dark  granules  lying  in  the  protoplasm  are  thrown  into 
a  trembling  movement,  from  the  motion  of  the  fluid  in  which  they  are 
suspended.     This  dancing  motion  stops  when  the  cell  dies. 

[The  Brownian  movements  of  these  suspended  granules  are  purely  physical, 
and  are  exhibited  by  all  fine  microscopic  particles  suspended  in  a  limpid  fluid — 
e.g.,  gamboge  rubbed  vip  in  water,  particles  of  carmine,  charcoal,  &c.] 

(6.)  Pavement  epithelial  cells  from  the  mucous  membrane  of  the  mouth  and 
tongue  ;  they  are  very  abundant  in  catarrh  of  the  mouth  (Fig.  115,  8). 

(c.)  Living  organisms,  which  live  and  thrive  in  the  cavities  of  teeth  nourished 
by  the  remains  of  food.  Amongst  these  are  Leptothrix  buccalis  (Fig.  115,  12) 
and  small  bacteria-like  organisms. 

(3.)  Chemical  Properties — (a.)  Organic  Constituents. — Serum-alhumhi 
is  precipitated  by  heat  and  by  the  addition  of  alcohol.  In  saliva,  mixed 
with  much  water  and  shaken  up  with  CO2,  a  globulin-like  body  is 
precipitated ;  mucin  occurs  in  small  amount.  Amongst  the  extractives, 
the  most  important  is  ptyalin  (Berzelius) ;  fats  and  urea  occur  only  in 
traces.  In  twenty-four  hours  130  milligrammes  of  potassium  or  sodium 
sulphocyanide  are  secreted. 

(b.)  Inorganic  Constituents. — Sodium  and  potassium  chlorides,  potas- 
sium sulphate,  alkaline  and  earthy  phosphates,  ferric  phosphate. 

Abnormal  Constituents. — In  diabetes  mellitus,  lactic  acid,  derived  from  a 
further  decomposition  of  grape-sugar,  is  found  (Lehmann).  It  dissolv-es  the 
lime  in  the  teeth,  giving  rise  to  diabetic  dental  caries.  Frerichs  found  leucin,  and 
Vulpian  increase  of  albumin  in  albuminuria.  Of  foreign  substances  taken  into 
the  body,  the  following  appear  in  the  saliva  : — Mercury,  potassium,  iodine,  and 
bromine. 

Saliva  of  New-born  Children. — In  new-born  children,  the  parotid 
alone  contains  ptyalin.  The  diastatic  ferment  seems  to  be  developed 
in  the  sub-maxillary  gland,  and  pancreas  at  the  earliest  after  two 
months.  Hence,  it  is  not  advisable  to  give  starchy  food  to  infants. 
No  ptyalin  has  been  found  in  the  saliva  of  infants  suffering  from 
thrush  (Oidium  albicans — Zweifel). 

The  diastatic  action  of  saliva  is  not  absolutely  necessary  for  the 
suckling,  feeding  as  it  does  upon  milk.  The  mouth  during  the  first 
two  months  is  not  moist,  but  at  a  later  period  saliva  is  copiously 
secreted  (Korowin) ;  after  the  first  six  months,  the  salivary  glands? 


294  PHYSIOLOGICAL   ACTION    OF   SALIVA. 

increase  considerably.  The  eruption  of  the  teeth — owing  to  the 
irritation  of  the  mucous  membrane — produces  a  copious  secretion  of 
saliva. 

148.  Physiological  Action  of  Saliva. 

I.  The  most  important  part  played  by  saliva  in  digestion  is  its 
diastatic  or  amylolytic  action  (Leuchs,  1831) — i.e.,  the  transformation  of 
starch  into  dextrin  and  some  form  of  sugar.  This  is  due  to  the  ptyalin 
— a  hydrolytic  ferment  or  enzym — which  acts  in  very  minute  quantity, 
so  that  starch  takes  up  water  and  becomes  soluble,  the  ferment  itself 
undergoing  no  essential  change  in  the  process.  [Ptyalin  belongs  to 
the  group  of  unorganised  ferments.  Like  all  other  ferments  it  acts 
only  within  a  certain  range  of  temperature,  being  most  active  about 
40°C.  Its  energy  is  permanently  destroyed  by  boiling.  It  acts  best 
in  a  slightly  alkaline  or  neutral  medium.] 

Action  on  Starch. — [Starch  grains  consist  of  granulose  or  starch 
enclosed  by  coats  of  cellulose.  Cellulose  does  not  appear  to  be  affected 
by  saliva,  so  that  saliva  acts  but  slowly  on  raw,  unboiled  starch.  If 
the  starch  be  boiled  so  as  to  swell  up  the  starch  grains  and  rupture  the 
cellulose  envelopes,  the  amylolytic  action  takes  place  rapidly.] 

[If  starch  paste  or  starch-mucilage,  made  by  boiling  starch  in  water, 
be  acted  upon  by  saliva,  especially  at  the  temperature  of  the  body,  the 
first  physical  change  observable  is  the  liquefaction  of  the  paste,  the 
mixture  becoming  more  fluid  and  transparent.  The  change  takes  place 
in  a  few  minutes.  When  the  action  is  continued,  important  chemical 
changes  occur.] 

According  to  O'Sullivan,  Musculus,  and  v.  Mering,  the  diastatic 
ferment  of  saliva  (and  of  the  pancreas)  by  acting  upon  starch 
or  glycogen  forms  maltose  and  dextrin  (both  soluble  in  water). 
Several  closely  allied  varieties  of  dextrin,  distinguishable  by  their 
colour  reactions,  seem  to  be  produced  (Briicke).  Erythrodextrin  is 
formed  first;  it  gives  a  red  colour  with  iodine,  then  a  reducing 
dextrin — Achroodextrin,  which  gives  no  colour  reaction  with  iodine. 
The  sugar  formed  by  the  action  of  ptyaline  upon  starch  is  maltose 
(C12H22O11  +  H2O),  which  is  distinguished  from  grape-sugar  (C12H24O12) 
by  containing  one  molecule  less  of  water,  which,  however,  it  holds 
as  a  molecule  of  water  of  hydration,  as  indicated  in  the  formula  given 
above  (Ad.  Mayer).  [Maltose  also  diflfers  from  grape-sugar  in  its 
greater  rotatory  power  on  polarised  light,  and  in  its  less  power  of 
reducing  cupric  oxide.] 

[Thus,  it  will  be  seen  that  between  the  original  starch  and  the  final 
product,  maltose,  several  intermediate  bodies  are  formed.     The  starch 


PHYSIOLOGICAL   ACTION    OF   SALIVA.  295 

gives  a  blue  with  iodine,  but  after  it  has  been  acted  on  for  a  time  it 
gives  a  red  or  violet  colour,  indicating  the  presence  of  erythrodextrin, 
there  being  a  simultaneous  production  of  sugar;  but  ultimately  no 
colour  is  obtained  on  adding  iodine — achroodextrin,  which  gives  no 
colour  with  iodine,  and  maltose  being  formed.  The  presence  of  the 
maltose  is  easily  determined  by  testing  with  Fehling's  solution. 

Brown  and  Heron  suggest  that  the  final  result  of  the  transformation 
may  be  represented  by  the  equation — 

10  (C^^H^oOio)  +  8  H,0  =  8  (C,,H,,0,,)  +  2  (C^.H^oO,,) 
Soluble  starch.         Water.  Maltose.  Achroodextrin.] 

The  ferment  slowly  changes  maltose  into  grape-sugar  or  dextrose. 
This  result  may  be  brought  about  much  more  rapidly  by  boiling  maltose 
with  dilute  sulphuric  or  hydrochloric  acid.  Achroodextrin  ultimately 
passes  into  maltose,  and  this  again  into  dextrose ;  the  other  form  of 
dextrin  does  not  seem  to  undergo  this  change  (Seegen's  Dystropodex- 
trin).  For  the  further  changes  that  maltose  undergoes  in  the  intestine, 
see  Intestinal  Juice,  ii.,  2. 

[The  formula  of  starch  is  usually  expressed  as  CeHjoOs,  but  the  researches 
already  mentioned,  and  those  of  Brown  and  Heron,  make  it  probable  that  it  is  more 
complex,  which  we  may  provisionally  represent  by  n  (C12H20O10).] 

According  to  Musculus  and  Meyer,  erythrodextrin  is  a  mixture  of  dextrin  and 
soluble  starch. 

Preparation  of  Ptyalin.— (l.)  Like  all  other  hydrolytic  ferments,  it  is  carried 
down  with  any  copious  precipitate  that  is  produced  in  the  fluid  which  contains  it. 
It  is  easily  isolated  from  the  precipitate.  The  saliva  is  acidulated  with  phos- 
phoric acid,  and  lime-water  is  added  until  the  reaction  becomes  alkaline,  when  a 
precipitate  of  basic  calcium  phosphate  occurs,  which  carries  the  ptyaHne  along  with 
it.  This  precipitate  is  collected  on  a  filter  and  washed  with  water,  which  dissolves 
the  ptyaline,  and  from  its  watery  solution  it  is  precipitated  by  alcohol  as  a  white 
powder.  It  is  redissolved  in  water  and  reprecipitated,  and  is  obtained  pure  (Cohn- 
heim). 

(2.)  V.  Witticli's  method. — The  salivary  glands  [rat]  are  chopped  up,  placed  in 
absolute  alcohol  for  twenty-four  hours,  taken  out  and  dried,  and  afterwards 
placed  in  glycerine  for  several  days.  The  glycerine  extracts  the  ptyaHn.  It  is 
precipitated  by  alcohol  from  the  glycerine  extract. 

(3.)  William  Roberts  recommends  the  following  solutions  for  extracting  ferments 
from  organs  which  contain  them: — (1)  A  3-4  p.c.  solution  of  a  mixture  of  two  parts 
of  boracic  acid  and  1  part  borax.  (2)  Water,  with  12-15  p.c.  of  alcohol.  (3)  One 
part  chloroform  to  200  of  water. 

Diastatic  action  of  Saliva. — («.)  The  diastatic  or  sugar-forming  action  is 
known  by:— (1)  The  disappearance  of  the  starch.  When  a  smaU  quantity  of  starch 
is  boiled  with  several  hundred  times  its  volume  of  water,  starch  mucilage  is 
obtained,  which  strikes  a  blue  colour  with  iodine.  If  to  a  small  quantity  of  this 
starch  a  sufficient  amount  of  saliva  be  added,  and  the  mixture  kept  for  some 
time  at  the  temperature  of  the  body,  the  blue  colour  disappears.  (2)  The  presence 
of  sugar  is  proved  directly  by  using  the  tests  for  sugar  (§  149). 

(6.)  The  action  takes  place  more  slowly  in  the  cold  than  at  the  temperature  of 


296  FUNCTIONS   OF  SALIVA. 

the  body — its  action  ia  enfeebled  at  55°C.,  and  destroyed  at  75°C.  (Paschutin). 
The  most  favourable  temperature  is  35°-39°C. 

(c.)  The  ptyalin  itself  does  not  seem  to  be  changed  during  its  action,  but 
ptyalin  which  has  been  used  for  one  experiment,  is  less  active  when  used  the 
second  time  (Paschutin). 

(d,)  Saliva  acts  best  in  a  slightly  alkaline  medium,  but  it  also  acts  in  a  neutral 
and  even  in  a  slightly  acid  fluid;  strong  acidity  prevents  its  action.  The  ptyalin 
is  only  active  in  the  stomach  when  the  acidity  is  due  to  organic  acids  (lactic  or 
butyric),  and  not  when  free  hydrochloric  acid  is  present  (von  den  Velden).  In 
both  cases,  however,  dextrin  is  formed.  Ptyalin  is  destroyed  by  hydrochloric 
acid  or  digestion  by  pepsin  (Chittenden  and  Griswold).  Even  butyric  and  lactic 
acids  formed  from  grape-sugar  in  the  stomach  may  prevent  its  action;  but  if  the 
acidity  be  neutralised,  the  action  is  resumed  (CI.  Bernard). 

(e.)  The  addition  of  common  salt,  ammonium  chloride,  or  sodium  sulphate  (4  p.c. 
solution),  increases  the  activity  of  the  ptyalin,  and  so  do  CO2,  acetate  of 
quinine,  strychnia,  morphia,  curara,  0'025  p.c.  sulphuric  acid. 

(/. )  Much  alcohol  and  caustic  potash  destroy  the  ptyalin ;  long  exposure  to  the 
air  weakens  its  action.  Salicylic  acid  and  much  atropin  arrest  the  formation  of 
sugar. 

(qt.)  Ptyalin  acts  very  feebly  and  very  gradually  upon  raw  starch,  only  after 
2-3  hours  (Schiff);  while  upon  boiled  starch  it  acts  rapidly.  [Hence  the  necessity 
for  boiling  thoroughly  all  starchy  foods.] 

(Ji.)  The  various  kinds  of  starch  are  changed  more  or  less  rapidly  according  to 
the  amount  of  cellulose  which  they  contain;  raw  potato-starch  after  2-3  hours, 
raw  maize-starch  after  2-3  minutes  (Hammarsten).  Starch  cellulose  is  dissolved 
at  55°C.  (Nageli).  When  the  starches  are  powdered  and  boiled,  they  are  changed 
with  equal  rapidity. 

(i. )  A  mixture  of  the  saliva  from  all  the  glands  is  more  active  than  the  saliva 
from  any  single  gland  (Jakubowitsch),  while  mucin  is  inactive.  Ptyalin  differs 
from  diastase  in  so  far  that  the  latter  first  begins  to  act  at  +  66°C.  Ptyalin 
decomposes  salicin  into  saligenin  and  grape-sugar  (Frerichs  and  Stadler),  but  it 
has  no  action  on  cane-sugar  and  amygdalin. 

II.  Saliva  dissolves  those  substances  which  are  soluble  in  water ; 
while  the  alkaline  reaction  enables  it  to  dissolve  some  substances  which 
are  not  soluble  in  water  alone,  but  require  the  presence  of  an  alkali. 

III.  Saliva  moistens  dry  food  and  aids  the  formation  of  the  "  bolus," 
while  by  its  mucin  it  aids  the  act  of  swallowing,  the  mucin  being 
given  off  unchanged  in  the  fseces.  The  ultimate  fate  of  ptyalin  is 
unknown. 

[IV.  Saliva  also  aids  articulation,  while  according  to  Liebig  it 
carries  down  into  the  stomach  small  quantities  of  0.] 

[V.  It  is  necessary  to  the  sense  of  taste  to  dissolve  sapid  substances, 
and  bring  them  in  relation  with  the  end-organs  of  the  nerves  of  taste.] 

The  presence  of  a  peptone-forming  ferment  has  recently  been  detected  in  saliva 
(Hiifner,  Munk,  Ktihne).  This  ferment  is  likewise  said  to  occur  in  the  saliva  of  the 
horse,  which  can  also  convert  cane-sugar  into  invert  sugar,  and  slightly  emul- 
sionise  fats  (Ellenberger  and  v.  Hofmeister).  According  to  Hofmeister,  the  saliva 
of  the  sheep  has  a  digestive  action  on  cellulose . 

Saliva  has  no  action  on  proteids,  while  on  fats  it  produces  a  very 
feeble  emulsion, 


TESTS  FOR   SUGAR.  297 


149.  Tests  for  Sugar. 

1.  Trommer's  Test  depends  upon  the  ftict  that  in  alkaline  solutionf; 
sugar  acts  as  a  reducing  agent ;  in  this  case  a  metallic  oxide  is  changed 
into  a  suboxide.  To  the  fluid  to  be  investigated,  add  |-  of  its  volume  of 
a  solution  of  caustic  potash  (soda)  specific  gravity  r25,  and  a  few 
drops  of  a  weak  solution  of  cupric  sulphate,  which  causes  at  first  a 
bluish  precipitate  consisting  of  hydrated  cupric  oxide,  but  it  is  redis- 
solved  giving  a  clear  blue  fluid,  if  sugar  be  present.  Heat  the  upper 
stratum  of  the  fluid,  and  a  yellow  or  red  ring  of  cuprous  oxide  is 
obtained,  which  indicates  the  presence  of  sugar;  2  CuO  — 0  =  Cu20. 

The  solution  of  hydrated  cupric  oxide  is  caused  by  other  organic  substances;  but 
the  final  stage,  or  the  production  of  cuprous  oxide  is  obtained  only  with  certain 
sugars — grape,  fruit  and  milk  (but  not  cane)  sugar.  Fluids  which  are  turbid  must  be 
previously  filtered,  and  if  they  are  highly  coloured  they  must  l)e  treated  with  basic 
lead  acetate ;  the  lead  acetate  is  afterwards  removed  by  the  addition  of  sodium 
phosphate  and  subsequent  filtration.  If  very  small  quantities  of  sugar  are  present 
along  with  compounds  of  ammonia,  a  yellow  colour  instead  of  a  yellow  precipitate 
may  be  obtained.  In  doing  the  test,  care  must  be  taken  not  to  add  too  much 
cupric  sulphate. 

[2.  Fehling's  Solution  is  an  alkaline  solution  of  potassio-tartarate  of 
copper.  Boil  a  small  quantity  of  the  deep-blue  coloured  Fehling's 
solution  in  a  test  tube,  and  add  to  the  boiling  test  a  few  droj^s  of  the 
fluid  supposed  to  contain  the  sugar.  If  sugar  be  present  the  copper 
solution  is  reduced,  giving  a  yellow  or  reddish  precipitate.  The 
reason  for  boiling  the  test  itself  is,  that  the  solution  is  apt  to  decom- 
pose when  kept  for  some  time,  when  it  is  precipitated  by  heat  alone. 
This  is  one  of  the  best  and  most  reliable  tests  for  the  presence  of 
sugar.  In  Pavy's  modification  of  this  test,  ammonia  is  used  instead  of 
a  caustic  alkali.] 

3.  Bottger's  Test.— Alkaline  bismuth  oxide  solution  (5  grammes  each  of  basic 
bismuth  nitrate,  and  tartaric  acid,  30  cubic  centimetres  water,  and  caustic  soda 
sufficient  for  neutralisation)  is  reduced  to  bismuth  suboxide  by  sugar,  with  the 
formation  of  a  dark  olive  green  and  ultimately  black  precipitate. 

4.  Moore  and  Heller's  Test.— Caustic  potash  or  soda  is  added  until  the 
mixture  is  strongly  alkaline ;  it  is  afterwards  boiled.  If  sugar  be  present,  a  yellow, 
brown  or  brownish-black  colouration  is  obtained.  If  nitric  acid  be  added,  the 
odour  of  burned  sugar  (caramel)  and  formic  acid  is  obtained. 

5.  Mulder  and  Neubauer's  Test.— A  solution  of  indigo-carmine  rendered 
alkaline  with  sodic  carbonate,  is  added  to  the  sugar-solution  until  a  slight  bluish 
colour  is  obtained.  When  the  mixture  is  heated  the  colour  passes  into  purple,  red, 
and  yellow.     When  shaken  with  atmospheric  air,  the  fluid  again  becomes  blue. 

In  all  cases  where  albumin  is  present  it  must  be  removed — in  urine  by  acidula- 
ting with  acetic  acid  and  boiling;  in  blood,  by  adding  four  times  its  volume  of 
alcohol  and  afterwards  filtering,  while  the  alcohol  is  expelled  by  heat. 


298 


QUANTITATIVE   ESTIMATION    OF   SUGAR. 


150.  duantitative  Estimation  of  Sugar. 


I.  By  Fermentation. — Into  the  glass  vessel 
(Fig.  121,  a)  a  measured  quantity  (20  cmtr.)of 
the  fluid  (sugar)  is  placed  along  with  some  yeast, 
while  b  contains  concentrated  sulphuric  acid. 
The  whole  apparatus  is  now  weighed.  When 
exposed  to  a  sufficient  temperature  (10-40°C.), 
the  sugar  splits  into  2  molecules  of  alcohol  and 
2  of  carbonic  acid, 


Fig.  121. 


Apparatus  for  the  quantitative 
estimation  of  sugar  by  fer- 
mentation. 


C6Hi206  =  2(C2H60)+2(C02), 

Grape-sugar  =  2  alcohol  +  2  carbonic  acid  ; 

and  in  addition  there  are  formed  traces 
of  glycerine  and  succinic  acid.  The  CO2 
escapes  from  b,  and  as  it  passes  through  the 
H2SO4,  CO2  yields  to  the  latter  its  water.  The  apparatus  is  weighed  after  two 
days,  when  the  reaction  is  ended,  and  the  amount  of  sugar  is  calculated  from  the 
loss  of  weight  in  the  20  cmtr.  of  fluid.  100  parts  of  water -free  sugar  =  48*89 
parts  CO2,  or  100  parts  CO2  correspond  to  204'54:  parts  of  sugar. 

II.  Titration. — By  means  of  Fehliug's  solution,  which  consists  of  cupric  sul- 
phate, tartrate  of  potash  and  soda,  caustic  soda,  and  water.  It  is  made  of  such 
a  strength  that  all  the  copper  in  10  cubic  centimetres  of  the  solution  is  reduced  by 
0"05  grammes  of  grape-sugar  (see  Urine,  vol.  ii). 

III.  The  amount  may  also  be  estimated  by  the  polarisation  apparatus  (see  Urine, 
vol.  a.). 

151.  Mechanism  of  the  Digestive  Apparatus. 

This  embraces  the  following  acts  : — 

1.  The  introduction  of  the  food  ;  the  movements  of  mastication  and 
those  of  the  tongue ;  insalivation  and  the  formation  of  the  bolus  of  food. 

2.  Deglutition. 

3.  The  movements  of  the  stomach,  of  the  small  and  large  intestine. 

4.  The  excretion  of  fsecal  matters. 


152.  Introduction  of  the  Food. 

Fluids  are  taken  into  the  mouth  in  three  ways: — (1)  By  suction,  the  lips 
are  applied  air-tight  to  the  vessel  containing  the  fluid,  while  the  tongue  is 
retracted  (the  lower  jaw  being  often  depressed)  and  acts  like  the  piston  in 
a  suction  pump,  thus  causing  the  fluid  to  enter  the  mouth.  Herz 
found  that  the  negative  pressure  caused  by  an  infant  while  sucking 
=  3-10  mm.  Hg.  (2)  The  fluid  is  lapped  when  it  is  brought  into 
direct  contact  with  the  lips,  and  is  raised  by  aspiration  and  mixed 
with  air  so  as  to  produce  a  characteristic  sound  in  the  mouth.  (3) 
Fluid  may  be  poured  into  the  mouth,  and  as  a  general  rule  the  lips  are 
applied  closely  to  the  vessel  containing  the  fluid. 

The  solids  when  they  consist  of  small  particles  are  licked  up  with 
the  lips,  aided  by  the  movements  of  the  tongue.     In  the  case  of  large- 


THE   jMOVEMENTS   OF  MASTICATION.  299 

masses,  a  part  is  bitten  off  with  the  incisor  teeth,  and  is  afterwards 
brought  under  the  action  of  the  molar  teeth  by  means  of  the  lips, 
cheeks,  and  tongue. 

153.  The  Movements  of  Mastication. 

The  articulation  of  the  jaw  is  provided  with  an  interarticular  cartilage  (Vidius, 
1567) — the  meniscus — which  prevents  direct  pressure  being  made  upon  the 
articular  surface  when  the  jaws  are  energetically  closed,  and  which  also  di\ades 
the  joint  into  two  cavities,  one  lying  over  the  other.  The  capsule  is  so  lax  that, 
in  addition  to  the  raising  and  depressing  of  the  lower  jaw,  it  pei-mits  of  the  lower 
jaw  being  displaced  forwards  upon  the  articular  tubercle,  whereby  the  meniscus 
moves  with  it,  and  covers  the  articular  surface. 

The  process  of  mastication  consists  of  the  following  movements  : — 
{a.)  The  elevation  of  the  jaw  is  accomplished  by  the  combined  action 
of  the  Temporal,  Masseter,  and  Internal  Pterygoid  Muscles.  If  the 
lower  jaw  was  previously  so  far  depressed  that  its  articular  surface 
rested  upon  the  tubercle,  it  now  passes  backwards  upon  the  articular 
surface. 

(b)  The  depression  of  the  loiver  jaiu  is  caused  by  its  own  weight, 
aided  by  the  action  of  the  anterior  bellies  of  the  Digastrics,  the  Mylo- 
and  Genio-hyoid  and  Platysma  (Haller).  The  muscles  act  during 
forcible  opening  of  the  mouth.  The  necessary  fixation  of  the  hyoid 
bone  is  obtained  through  the  action  of  the  Omo-  and  Sterno-hyoid, 
and  by  the  Sterno-thyroid  and  Thyro-hyoid. 

When  the  articular  surface  of  the  lower  jaw  passes  forwards  on  to  the  tubercle, 
the  External  Pterygoids  actively  aid  in  producing  this  (Berard). 

(c.)  Displacement  of  both  or  one  articular  surface  forwards  (rr  backwards. 
During  rest,  when  the  mouth  is  closed,  the  incisor  teeth  of  the  lower 
jaw  fall  Avithin  the  arch  of  the  upper  incisors.  When  in  this  position, 
the  jaw  is  protruded  by  the  External  Pterygoids,  whereby  the  articular 
surface  passes  on  to  the  tubercle  (and,  therefore,  downwards),  while  the 
lateral  teeth  are  thereby  separated  from  each  other.  The  jaw  is 
retracted  by  the  Internal  Pterygoids  without  any  aid  from  the 
posterior  fibres  of  the  Temporals.  When  one  articular  surface  is 
carried  forwards,  the  jaw  is  protruded  and  retracted  by  the  External 
and  Internal  Pterygoid  of  the  same  side.  At  the  same  time,  there  is 
a  transverse  movement,  whereby  the  back  teeth  of  the  protruded  side 
are  separated  from  each  other. 

During  mastication,  when  the  individual  movements  of  the  lower 
jaw  are  variously  combined,  the  food  to  be  masticated  is  kept  from 
passing  outwards  by  the  action  of  the  muscles  of  the  lips  (Orbicularis 
oris)  and  the  Buccinators,  while  the  tongue  continually  pushes  the 
particles  between  the  molar  teeth.      The   energy  of  the  muscles  of 


300 


STRUCTURE    OF    THE    TEETH. 


mastication  is  regulated  by  the  sensibility  of  the  teeth,  and  the  muscular 
sensibility  of  the  muscles  of  mastication,  as  -well  as  by  the  general 
sensibility  of  the  mucous  membrane  of  the  mouth  and  lips.  At  the 
same  time,  the  mass  is  mixed  with  saliva,  the  divided  particles  cohere, 
and  are  formed  into  a  mass  or  bolus  of  a  long,  oval  shape  by  the 
muscles  of  the  tongue.  The  bolus  then  rests  on  the  back  of  the  tongue, 
ready  to  be  swallowed. 

Nerves  of  Mastication. — The  muscles  of  mastication  and  the  buccinator 
receive  their  motor  nerves  from  the  third  branch  of  the  trigeminus;  the  mylo- 
hyoid and  the  anterior  belly  of  the  digastric  being  supplied  from  the  same  source. 
The  genio-,  omo-,  and  sterno-hyoid,  sterno-thyroid,  and  thyro-hyoid  are  supplied 
by  the  hypoglossal,  while  the  facial  supplies  the  posterior  belly  of  the  digastric, 
the  stylo-hyoid,  the  platysma,  and  the  muscles  of  the  lips.  The  general  centre  for 
the  muscles  of  mastication  lies  in  the  medulla  oblongata. 

When  the  mouth  is  closed,  the  jaws  are  kept  in  contact  by  the  pressure  of  the 
air,  as  the  cavity  of  the  mouth  is  rendered  free  from  air,  and  the  entrance  of  air  is 
prevented  anteriorly  by  the  lips,  and  posteriorly  by  the  soft  palate.  The  pressure 
exerted  by  the  air  is  from  2-4  mm.  Hg.  (Metzger  and  Donders). 

154.  Structure  and  Development  of  the  Teeth. 

A  tooth  is  just  a  papilla  of  the  mucous  membrane  of  the  gum,  which  has  imder- 
gone  a  characteristic  development.  In  its  simplest  form,  as  in  the  teeth  of  the 
lamprey,  the  connective-tissue  basis  of  the  papilla  is  covered  with  many  layers  of 
corneous  epithelium.  In  human  teeth,  part  of  the  papilla  is  transformed  into 
a  layer  of  calcified  dentine,  while  the  epithelium  of  the  papilla  produces  the 
enamel,  the  fang  of  the  tooth  being  covered  by  a  thin  accessory  layer  of  bone,  the 
crusta  petrosa  or  cement. 

The  dentine  or  ivory  which  surrounds  the  pulp  cavity  and  the  canal  of  the 
fang  (Fig.  122)  is  very  firm,  elastic,  and  brittle.     Like  the  matrix  of  bone,  dentine, 

when  treated  in  a  certain 
way,  presents  a  fibrillar 
structure  (v.  Ebner).  It 
is  permeated  by  innumer- 
able long,  tortuous,  wavy 
tubes — the  dentina  Itubu  les 
(Leeuwenhoek,  1678) — 
each  of  which  commuui- 
cates  with  the  pulp  cavity 
by  means  of  a  fine  opening, 
and  passes  more  or  less 
horizontally  outwards  as 
far  as  the  outer  layers  of 
the  dentine.  The  tubules 
are  bounded  by  an  ex- 
tremely resistant,  thin, 
cuticular  membrane, 
which  strongly  resists 
the  action  of  chemical 
reagents.  These  tubules 
are  tilled  completely  by 


Fig.  123. 

Transverse  section  of  dentine — 
The  light  rings  are  the  walls 
of  the  dentinal  tubules  ;  the 
dark  centres  with  the  light 
points  are  the  fibres  of 
Tomes  lying  in  the  tubules. 

soft  fibres,  the  "fibres  of  Tomes''  (1840),  which  are  merely  greatly  elongated  and 
branched  processes  of  the  odontoblasts  of  the  pulp  (Waldeyer,  1865). 


Fig.  122. 

Vertical  section  of  a 

tooth  —  p,     pulp 

cavity;  d,  dentine; 

c,  cement;  s,enamel. 


STRUCTURE   OF  THE  TEETH. 


301 


The  dentinal  tubules,  as  well  as  the  fibres  of  Tomes,  anastomose  throughout 
their  entire  extent  by  means  of  fine  processes.  As  the  fibres  approach  the  enamel, 
■which  they  do  not  penetrate,  some  of  them  bend  on  themselves,  and  form  a  loop 
(Fig.  124,  c),  whilst  others  pass  into  the  ^^  inter glohular  spaces,^'  which  are  so 
abundant  in  the  outer  part  of  the  dentine  (Czermak,  1S50).  These  interglobular 
spaces  are  small  sjjaces  bounded  by  curved  surfaces.  Certain  curved  lines 
"  Schreger's  lines^'  (ISOO),  may  be  detected  with  the  naked  eye  in  the  dentine  (e.g., 
of  the  elephant's  tusk)  running  parallel  with  the  contour  of  the  tooth.  They  are 
caused  by  the  fact  that  at  these  parts  all  the  chief  curves  in  the  dentinal  tubules 
follow  a  similar  course  (Retzius,  1837). 

The  enamel,  the  hardest  substance  in  the  body  (resembling  apatite),  covers 
the  crown  of  the  teeth.  It  consists  of  hexagonal  flattened  prisms  (Malpighi,  1687) 
arranged  side  by  side  like  a  palisade  (Fig.  124,  a  and  B).  They  are  3-5 /u  (^jVo  inch) 
broad,  not  quite  uniform  in  thickness,  curved  slightly  in  diilerent  directions,  and 


Fig.  124. 
Section  of  a  tooth  between  the  dentine  and  enamel — a,  enamel;  c,  dentinal  tubules; 
B,  enamel  prisms  highly  magnified. 

owing  to  inequalities  of  thickness,   they  exhibit  transverse  markings.     They  are 
elongated,  calcified,  cylindrical,  epithelial  cells  derived  from  the  dental  papilla. 

Retzius  described  dark-brown  lines  running  parallel  with  the  outer  boundary  of 
the  enamel,  due  to  the  presence  of  pigment.  The  fully-formed  enamel  is  nega- 
tively doubly  refractive  and  uniaxial,  while  the  developing  enamel  is  positively 
doubly  refractive  (Hoppe-Seyler). 

The  cuticnla  or  Nasmyth's  membrane  (1839)  covers  the  free  surface  of  the 
enamel  as  a  completely  structureless  membrane  1-2^  thick,  but  in  quite  young 
teeth  it  exhibits  an  epithelial  structure,  and  is  derived  from  the  outer  epithelial 
layer  of  the  enamel- organ. 

The  cement  (John  Hunter,  1778)  or  crusta  petrosa,  is  a  thin  layer  of 
bone  covering  the  fang  (Fig.  125,  a).  The  bone  lacunse  communicate  directly 
with  the  dentinal  tubules  of  the  fang.  Haversian  canals  and  lamellae  are  only 
found  where  the  layer  of  cement  is  thick,  and  the  former  may  communicate 
with  the  pulp-cavity  (Salter).  Very  thin  layers  of  cement  may  be  devoid  of 
bone-corpuscles.  Sharpey's  fibres  occur  in  the  cement  of  the  dog's  tooth  (Wal- 
deyer) ;  while  in  the  horse's  tooth  single  bone  corpuscles  are  enveloped  by  a 
capsule  (Gerber).  In  the  periodontal  membrane,  which  is  just  the  periosteum 
of  the  alveolus,  coils  of  blood-vessels  similar  to  the  renal  glomeruli  occur. 
They  anastomose  with  each  other,  and  are  surrounded  with  a  delicate  capsule 
of  connective-tissue  (C.  Wedl). 


302 


CHEMISTRY   OF  A  TOOTH. 


G •; 


Transverse  section  of  the  fang  —  a, 
cement  with,  bone-corpuscles;  b, 
dentine  mth  dentinal  tubules;  c, 
boundary  between  both. 


Chemistry  of  a  Tooth. — The  teeth  consist  of  a  gelatine-yielding  matrix  infil- 
trated with  calcium  phosphate  and  carbonate  (like  bone). — 1.  The  dentine  con- 
tains— organic  matter,  27  "70;  calcium  phosphate  and  carbonate,  72 "06;  magnesium 
phosphate,  0*7o,  with  traces  of  iron,  fluorine,  and  sulphuric  acid  (Aeby,  Hoppe- 
Seyler). 

2.  The  enamel  contains  an  organic 
proteid  matrix  allied  to  the  substance 
of  epithelium.  It  contains  3 "60  organic 
matter  and  96  "00  of  calcium  phosphate 
and  carbonate,  1'05  magnesium  phos- 
phate, with  traces  of  calcium  fluoride 
and  an  insoluble  chlorine  compound. 

3.  The  cement  is  identical  with 
bone. 

The  pulp  in  a  fully-grown  tooth  re- 
presents the  remainder  of  the  dental 
papilla  around  which  the  dentine  was 
deposited.  It  consists  of  a  very  vas- 
cular indistinctly  fibrillar  connective- 
tissue,  laden  with  cells.  The  layers  of 
cells,  resembling  epithelium,  which  lie 
in  direct  contact  with  the  dentine  are 
called  odontoblasts  (Waldeyer,  1865), 
i.e.,  those  cells  which  build  up  the 
dentine.  These  cells  send  off^  long 
branched  processes  into  the  dentinal  tubules,  whilst  their  nucleated  bodies 
lie  on  the  surface  of  the  pulp  and  form  connections  by  processes  with  other  cells 
of  the  pulp  and  with  neighbouring  odontoblasts.  Numerous  non-meduUated 
nerve-fibres  (sensory  fi'om  the  Trigeminus)  whose  mode  of  termination  is  unknown, 
occur  in  the  pulp. 

The  periosteum  or  periodontal  membrane  of  the  fang  is,  at  the  same 

time,  the  alveolar  periosteum,  and  consists  of  delicate  connective-tissue  with  few 
elastic  fibres  and  many  nerves. 

The  gums  are  devoid  of  mucous  glands,  are  very  vascular,  and  often  pro- 
vided with  long  vascular  papillse  which  are  sometimes  compound. 

Development  of  a  Tooth. — It  begins  at  the  end  of  the  second  month  of  fcetal 
life.  Along  the  whole  length  of  the  fcetal  gum  is  a 
thick  projecting  ridge  (Fig.  126,  a)  composed  of  many 
layers  of  epithehum.  A  depression,  the  dental 
groove  also  filled  with  epithelium,  occurs  in  the 
gum,  and  runs  along  under  the  ridge.  The  dental 
groove  becomes  deeper  throughout  its  entire  length, 
and  on  transverse  section  presents  the  appearance  of 
a  dilated  flask  (6),  while  at  the  same  time  it  is  filled 
with  elongated  epithelial  cells,  which  form  the 
"enamel-organ.^''  A  conical  papilla  (the  ^^dentine- 
germ  ")  grows  up  from  the  mucous  tissue,  of  which 
the  gum  consists,  towards  the  enamel-organ  (Fig. 
127,  c),  so  that  the  apex  of  the  papilla  comes  to  have 
the  enamel-organ  resting  upon  it  like  a  double  cap. 
Afterwards,  owing  to  the  development  of  connective- 
tissue,  the  parts  of  the  enamel-organ  lying  between 
and  uniting  the  individual  dentine-germs  disappear, 
and  gradually  the  connective -tissue  forms  a  tooth- 
sac  enclosing  the  papilla  and  its  enamel-organ  (d). 


a,  Dental  ridge  ;  b,  enamel - 
organ ;  c,  beginning  of 
the  dentine-germ ;  d,  first 
indication  of  the  tooth - 
sac. 


DEVELOPMENT   OF   THE   TEETH. 


303 


Those  epithelial  cells  (Fig.  127,  3)  of  the  enamel-organ,  which  lie  next  the  top  of 
the  papilla,  are  cylindrical,  and  become  calcified  to  form  enamel  prisms.  The 
layer  of  cells  of  the  double  cap,  which  is  directed  towards  the  tooth-sac  (1), 
becomes  flattened,  fiises,  undergoes  a  horny  transformation,  and  becomes  the 
cuticula,  whilst  the  cells  which  lie  between  both  layers  undergo  an  intermediate 
metamorphosis,  so  that  they  come  to  resemble  the  branched  stellate  cells  of  the 
mucous  tissue  (2),  and  gradually  disappear  altogether. 

The  dentine  is  formed  in  the  most  superficial  layer  of  the  projecting  connective- 
tissue  of  the  dental  papilla,  owing  to  the  calcification  of  the  continuous  layer  of 
odontoblasts  which  occurs  there  (Figs.  127  and  128,  k).     During  the  process,  fibres 


Fig.  127. 

a,  Dental  ridge;  o,  euamel-orgau 
with  1,  oiiter  epithelium ;  2, 
middle  stellate  layer ;  3,  ena- 
mel-prism cell  layer  ;  c,  dea- 
tine-germ  with  blood-vessels 
and  the  long  osteoblasts  on 
the  surface  ;  d,  tooth  -  sac ; 
e,  secondary  enamel-germ. 


Fig.  128. 

Dental  ridge  ;  b,  enamel-organ  ; 
c,  dentine-germ  ;  /,  enamel ;  r/, 
dentine  ;  k,  interval  between 
enamel- organ  and  the  position  of 
the  tooth  ;  I;  layer  of  odonto- 
blasts. 


or  branches  of  these  cells  are  left  unaffected,  and  remain  as  the  fibres  of  Tomes. 
Exactly  the  same  process  occurs  as  in  the  formation  of  bone,  the  odontoblasts 
forming  around  themselves  a  calcified  matrix.  The  cement  is  formed  from  the  soft 
connective-tissue  of  the  dental  alveolus. 

Dentition. — During  the  development  of  the  first  (temporary  or  milk)  teeth  a 
special  enamel-organ  (Fig.  127,  e)  is  formed  near  these,  but  it  does  not  undergo 
development  until  the  milk-teeth  are  shed ;  even  the  papilla  is  wanting  at  first. 
When  the  permanent  tooth  begins  to  develop,  it  opens  into  the  alveolar  wall  of  the 
milk-teeth  from  below. 

The  tissue  of  this  dental  sac  causes  erosion,  or  eating  away  of  the  fang  and  even 
of  the  body  of  the  milk-teeth,  without  its  blood-vessels  undergoing  atrophy.  The 
chief  agents  in  the  absorption  are  the  amoeboid  cells  of  the  granulation  tissue. 
[Multinuclear  giant-cells  also  erode  the  fangs  of  the  teeth.] 

Eruption  of  the  Teeth. — The  following  is  the  order  in  which  the  tAventy  milk- 
teeth  cut  the  gum — I.e. ,  from  the  seventh  month  to  the  second  year : — Lower  central 
incisors,  upper  central  incisors,  upper  lateral  incisors,  lower  lateral  incisors,  first 
molar,  canine,  the  second  molars. 

[The  figures  indicate  in  months  the  period  of  eruption  of  each  tooth.] 


304 


MOVEMENTS   OE  THE  TONGUE. 


Molars. 

Canines. 

Incisors. 

Canines. 

Molars. 

24     12 

18 

9779 

18 

24    12 

The  permanent  teeth  succeed  the  milk-teeth,  the  process  beginning  about  the 
seventh  year.  Ten  teeth  in  each  jaw  take  the  place  of  the  milk-teeth,  while  six 
teeth  appear  further  back  in  each  jaw.  Thus  the  total  number  of  permanent 
teeth  is  thirty-two.  As  the  sacs,  from  which  the  permanent  teeth  are  developed, 
are  formed  before  birth,  they  merely  undergo  the  same  process  of  development  as 
the  temporary  teeth,  only  at  a  much  later  period.  The  last  of  the  permanent 
molars — the  wisdom-tooth — may  not  cut  the  jaw  until  the  seventeenth  to  the  twenty- 
fifth  year.  At  the  sixth  year  the  jaw  contains  the  largest  number  of  teeth,  as 
all  the  temporary  teeth  are  present,  and,  in  addition,  the  crowns  of  all  the  per- 
manent teeth,  except  the  wisdom-tooth,  making  forty-eight  in  all. 

[Eruption  of  Permanent  Teeth. — The  age  at  which  each  tooth  cuts  the  gum  is 
given  in  years  in  the  following  table  : — 


Molars. 

Bicuspid. 

Canines. 

Incisors. 

Canines. 

Bicuspid. 

Molars. 

17    12 
to     to    6 
25    13 

10    9 

11  to  12 

8778 

11  to  12 

9     10 

12  17 
6    to     to 

13  25 

-(Kirkes.)] 


155.  Movements  of  the  Tongue. 


The  tongue  being  a  muscular  organ  (Aretaeus,  a.d.  81),  and 
extremely  mobile,  plays  an  important  part  in  the  process  of  mastica- 
tion : — (1)  It  keej)s  the  food  from  passing  from  between  the  molar 
teeth,  (2)  It  collects  into  a  bolus  the  finely-divided  food  after  it  is 
mixed  with  saliva.  (3)  When  the  tongue  is  raised,  the  bolus  lying  on 
its  dorsum  is  pushed  backwards  into  the  pharynx,  whence  it  passes 
into  the  oesophagus. 

The  muscular  fibres  of  the  tongue  run  in  three  directions — longi- 
tudinally, from  base  to  tip ;  transversely,  the  fibres  for  the  most  part 
proceeding  outwards  from  the  vertically  placed  septum  linguae  ;  vertically, 
from  below  upwards.  Some  of  the  muscles  are  confined  to  the  tongue 
(intrinsic),  while  others  (extrinsic),  are  attached  beyond  it  to  the  hyoid 
bone,  lower  jaw,  to  the  styloid  process,  and  the  palate. 

Microscopically,  the  fibres  are  transversely  striated,  with  a  delicate  sarcolemma, 
and  very  often  they  are  divided  where  they  are  inserted  into  the  mucous  membrane 
(Leeuwenhoek).  The  muscular  bundles  cross  each  other  in  various  directions, 
and  in  the  interspaces  fat  cells  and  glands  occur. 

On  analysing  the  lingual  movements,  we  may  distinguish  changes 
in  form  and  changes  in  position  : — 


DEGLUTITION.  305 

(1.)  Shorteuing  and  broadening  by  the  longitudinal  muscle,  aided  by 
the  hyo-glossus. 

(2.)  Elongation  and  narrowing,  by  the  transversus  linguse. 

(3.)  The  dorsum  rendered  concave  by  the  transversus  and  the 
simultaneous  action  of  the  median  vertical  fibres. 

(4.)  Arching  of  the  dorsum : — (a)  transversely  by  contraction  of  the 
lowest  transverse  bundles ;  (b)  longitudinally  by  the  action  of  the  lowest 
longitudinal  muscles. 

(5.)  Protrusion,  by  the  genio-glossus,  while  at  the  same  time  the 
tongue  usually  becomes  narroAver  and  longer  (2^. 

(6.)  Retraction,  by  the  hyo-glossus  and  stylo-glossus,  and  (1)  usually 
occurring  at  the  same  time. 

(7.)  Depression  of  the  tongue  into  the  floor  of  the  mouth,  by  the  hyo- 
glossus.  The  floor  of  the  mouth  may  be  made  deeper  by  simultaneously 
depressing  the  hyoid  bone. 

(8.)  Elevation  of  the  tongue  towards  the  gums  : — (a)  At  the  tip  by 
the  anterior  part  of  the  longitudinal  fibres ;  (b)  in  the  middle  by  eleva- 
ting the  entire  hyoid  bone  by  the  mylo-hyoid  (iV.  trigeminus) ;  (c)  at  the 
root  by  the  stylo-glossus  and  palato-glossus,  as  well  as  indirectly  by  the 
stylo-hyoid  (iV.  facialis). 

(9.)  Lateral  movements,  whereby  the  tip  of  the  tongue  passes  to  the 
right  or  the  left ;  these  are  caused  by  the  contraction  of  the  longitudinal 
fibres  of  one  side. 

Motor  Nerves, — The  proper  motor  nerve  of  the  tongiie  is  the  hypoglossal. 
When  this  nerve  is  divided  or  paralysed  on  one  side,  the  tip  of  the  tongue  lying 
in  the  floor  of  the  mouth  is  directed  towards  the  sound  side,  because  the  tonus  of 
the  non-paralysed  longitudinal  fibres  shortens  the  sound  side  slightly.  If  the 
tongue  be  protruded,  however,  the  tip  passes  towards  the  paralysed  side.  This 
arises  from  the  direction  of  the  genio-glossus  (from  the  middle  downwards  and 
outwards),  and  the  tongue  follows  the  direction  of  its  action.  The  tongues  of 
animals  which  have  been  killed  exhibit  fibrillar  contractions  of  the  muscles,  some- 
times lasting  for  a  whole  day  (Cardanus,  1550). 

156.  Deglutition. 

The  onward  movements  of  the  contents  of  the  digestive  canal  are 
effected  by  a  special  kind  of  action  whereby  the  tube  or  canal 
contracts  upon  its  contents,  and  as  this  contraction  proceeds  along  the 
tube,  the  contents  are  thereby  carried  along.  This  is  the  "peristaltic 
movement,"  or  peristalsis. 

In  the  first  and  most  complicated  part  of  the  act  of  deglutition,  we 
distinguish  in  order  the  following  individual  movements : — 

(1.)  The  aperture  of  the  mouth  is  closed  by  the  orbicularis  oris  (N, 
facialis). 

20 


306  DEGLUTITION. 

(2.)  The  jaws  are  pressed  against  each  other  by  the  muscles  of 
mastication  (N.  trigeminus),  while  at  the  same  time  the  lower  jaw 
affords  a  fixed  point  for  the  action  of  the  muscles  attached  to  it  and  the 
hyoid  bone. 

(3.)  The  tip,  middle,  and  root  of  the  tongue,  one  after  the  other,  are 
pressed  against  the  hard  palate,  whereby  the  contents  of  the  mouth  are 
propelled  towards  the  pharynx. 

(4.)  When  the  bolus  has  passed  the  anterior  palatine  arch  (the 
mncus  of  the  tonsillar  glands  making  it  slippery  again),  it  is  prevented 
from  returning  to  the  mouth  by  the  palato-glossi  muscles  which  lie  in 
the  anterior  pillars  of  the  fauces,  coming  together  like  two  side-screens 
or  curtains,  meeting  the  raised  dorsum  of  the  tongue  (Stylo-glossus 
— Dzondi,  1831). 

(5.)  The  morsel  is  now  behind  the  anterior  palatine  arch  and  the 
root  of  the  tongue,  and  has  reached  the  pharynx,  where  it  is  subjected 
to  the  successive  action  of  the  three  pharyngeal  constrictor-muscles 
which  propel  it  onwards.  The  action  of  the  superior  constrictor  of 
the  pharynx  is  always  combined  with  a  horizontal  elevation  (Levator 
veli  palatini;  N.  facialis),  and  tension  (Tensor  veli  palatini;  N.  trige- 
minus, otic  ganglion)  of  the  soft  palate  (Bidder,  1838).  The  upper 
constrictor  presses  (through  the  pterygo-pharyngeus)  the  posterior  and 
lateral  walls  of  the  pharynx  tightly  against  the  posterior  margin  of  the 
horizontal  tense  soft  palate  (Passavant),  whereby  the  margins  of  the 
posterior  palatine  arches  (palato-pharyngeus)  are  approximated.  The 
pharyngo-nasal  cavity  is  thus  completely  shut  off,  so  that  the  bolus 
cannot  be  pressed  backwards  into  the  nasal  cavity.  In  cases  where 
the  soft  palate  is  defective,  part  of  the  food  usually  passes  into  the 
nose. 

(6.)  The  bolus  is  propelled  onwards  by  the  successive  contractions 
of  the  constrictors  of  the  pharynx  until  it  passes  into  the  oesophagus. 
At  the  same  time  the  entrance  to  the  glottis  is  closed,  else  the  morsel 
would  pass  into  the  larynx. 

Talk  and  Ki'onecker  assert,  that  by  tlie  rapid  contraction  of  the  transversely 
striped  muscles  which  diminish  the  aperture  of  the  mouth,  the  bolus  is  projected 
into  the  oesophagus,  so  that  peristalsis  of  the  pharynx  and  oesophagus  only  occurs 
during  forced  deglutition. 

If  we  make  a  series  of  efforts  to  swallow,  one  after  the  other,  con- 
traction of  the  oesophagus  takes  place  only  after  the  last  attempt. 
Kronecker  and  Meltzer  found  that  stimulation  of  the  glosso-pharyngeal 
nerve  inhibited  the  act  of  deglutition  and  the  propagation  of  the  move- 
ment through  the  oesophagus.  Section  of  both  nerves  causes  tonic 
spasm  of  the  oesophagus  and  cardia. 


NERVES   CONCERNED   IN   DEGLUTITION.  307 

The  closure  of  the  glottis  is  eflfected  in  the  following  manner: — {a.)  The 
whole  larynx — the  lower  jaw  being  fixed — is  raised  upwards  and 
forwards,  while  at  the  same  time  the  root  of  the  tongue  hangs  over  it. 
The  hyoid  bone  is  raised  forwards  and  upAvards  by  the  genio-hyoid, 
anterior  belly  of  the  digastric  and  mylo-hyoid;  the  larynx  is  approxi- 
mated close  to  the  hyoid  bone  (Berengar,  1521)  by  the  thyro-hyoid. 

(6.)  When  the  larynx  is  raised  so  that  it  comes  to  lie  below  the  over- 
hanging root  of  the  tongue,  the  epiglottis  is  pressed  downwards  over 
the  entrance  to  the  glottis,  and  the  bolus  passes  over  it.  In  addition, 
the  epiglottis  is  pulled  down  by  the  special  muscular  fibres  of  the 
reflector  epiglottidis  (Thiele)  and  aryepiglotticus. 

Injury  to  the  Epiglottis. — Intentional  injury  of  the  epiglottis  in  animals,  or 
its  destruction  in  man  may  cause  fluids  to  "go  the  wrong  way,"  i.e.,  into  the 
glottis,  whilst  solid  food  can  be  swallowed  without  disturbance.  In  dogs,  at  any 
rate,  coloured  fluids  placed  on  the  root  of  the  tongue  have  been  observed  to  pass 
directly  into  the  pharynx  without  coming  into  contact  with,  so  as  to  tinge,  the 
upper  surface  of  the  epiglottis  (Magendie,  Schiff'). 

(c.)  Lastly,  the  closure  of  the  glottis  by  the  constrictors  of  the 
larynx  also  prevents  the  entrance  of  substances  into  the  larnyx 
(Czermak). 

In  order  that  the  descending  bolus  may  be  prevented  from  carrying 
the  pharynx  with  it,  the  stylo-pharyngeus,  salpingo-pharyngeus,  and 
baseo-pharyngeus  contract  upwards  when  the  constrictors  act. 

Nerves. — Deglutition  is  voluntary  only  during  the  time  the  bolus  is 
in  the  mouth.  When  the  food  passes  through  the  palatine  arch  into 
the  gullet  the  act  becomes  involuntary,  and  is,  in  fact,  a  well-regulated 
reflex  action.  When  there  is  no  bolus  to  be  swallowed,  voluntary 
movements  of  deglutition  can  be  accomplished  only  within  the  mouth ;  the 
pharynx  only  takes  up  the  movement  provided  a  bolus  (food  or  saliva) 
mechanically  excites  the  reflex  act.  The  sensory  nerves  which,  when 
mechanically  stimulated,  excite  the  involuntary  act  of  deglutition,  are, 
according  to  Schroeder  van  der  Kolk,  the  palatine  branches  of  the  tri- 
geminus (from  the  sphenopalatine  ganglion)  and  the  pharyngeal  branches 
of  the  vagus  (Waller,  Prevost).  The  centre  for  the  nerves  concerned 
(for  the  striped  muscles)  lies  in  the  superior  olives  of  the  medulla 
oblongata.  Swallowing  can  be  carried  out  when  a  person  is  uncon- 
scious, or  after  destruction  of  the  cerebrum,  cerebellum,  and  pons. 
[Even  in  the  deep  coma  of  alcoholism,  the  tube  of  a  stomach-pump 
is  readily  carried  into  the  stomach  reflexly,  provided  the  surgeon 
passes  it  back  into  the  pharynx  to  bring  it  within  the  action  of  the 
constrictors  of  the  pharynx.]  The  nerves  of  the  pharynx  are  derived 
from  the  pharyngeal  plexus,  which  receives  branches  from  the  vagus, 
glosso-pharyngeal,  and  sympathetic. 


308  NERVES   CONCERNED   IN   DEGLUTITION. 

Within  the  cesophagus,  whose  stratified  epithelium  is  moistened  with 
the  mucus  derived  from  the  mucous  glands  in  its  walls,  the  downward 
movement  is  involuntary,  and  depends  upon  a  complicated  reflex 
movement  discharged  from  the  centre  for  deglutition — there  is  a  peri- 
staltic movement  of  the  outer  longitudinal  and  inner  circular  non- 
striped  muscular  fibres. 

In  the  upper  part  of  the  cesophagus  which  contains  striped  muscular  fibres,  the 
peristalsis  takes  place  more  quickly  than  in  the  lower  part.  The  movements  of 
the  cesophagus  never  occur  independently,  but  are  always  the  continuation  of  a 
foregoing  act  of  deglutition.  If  food  be  introduced  into  the  cesophagus  through  a 
hole  in  its  wall,  there  it  lies;  and  it  is  only  carried  downwards  when  a  movement 
to  swallow  is  made  (Volkmann).  The  peristalsis  extends  along  the  whole  length 
of  the  cesophagus,  even  when  it  is  ligatured  or  when  a  part  of  it  is  removed 
(Mosso).  If  a  dog  be  allowed  to  swallow  a  piece  of  flesh  tied  to  a  string,  so  that 
the  flesh  goes  half-way  down  the  oesophagus,  and  if  the  flesh  be  withdrawn,  the 
peristalsis  still  passes  downwards  (C.  Ludwig  and  Wild). 

The  motor  nerve  of  the  cesophagus  is  the  vagus  (not  the  accessory  fibres);  after  it 
is  divided,  the  food  lodges  in  the  lower  part  of  the  cesophagus.  Very  large  and 
very  small  masses  are  swallowed  with  more  difficulty  than  those  of  moderate  size. 
Dogs  can  swallow  an  olive-shaped  body  weighted  with  a  counterpoise  of  450 
grammes  (Mosso).  When  the  thorax  is  greatly  distended,  as  in  MllUer's  experi- 
ment, or  greatly  diminished,  as  in  Valsalva's  experiment  (p.  112),  deglutition  is 
rendered  more  difficult. 

Goltz  observed,  that  the  cesophagus  and  stomach  (frog)  became  greatly  more 
excitable,  i.e.,  the  excitability  of  the  ganglionic  plexuses  in  their  walls  was 
increased,  when  the  brain  and  spinal  cord  or  both  vagi  were  destroyed.  These 
organs  contracted  energetically  after  slight  stimulation,  while  frogs  whose  cen- 
tral nervous  system  was  intact,  swallowed  fluids  simply  by  peristalsis.  Females, 
and  sometimes  men  also,  with  marked  weakening  of  the  nervous  system 
(Hysteria),  not  unfrequently  have  similar  spasmodic  contractions  of  the  cesophageal 
region  (globus  hystericus).  After  section  of  both  vagi,  Schiff  observed  spasmodic 
contraction  of  the  cesophagus. 

[Structure  of  the  (Esophagus. — The  walls  of  the  cesophagus  are 
composed  of  three  coats — mucous,  sub-mucous,  and  muscular. 

The  mucous  coat  is  firm  and  is  thrown  into  longitudinal  folds,  which 
disappear  when  the  tube  is  distended.  It  is  lined  by  several  layers  of 
stratified  squamous  epithelium.  The  membrane  itself  is  composed, 
especially  at  its  inner  part,  of  dense  fibrous  tissue,  which  projects  in 
the  form  of  papillae,  into  the  stratified  epithelium.  At  its  outer  part 
is  a  continuous  layer  of  non-striped  muscle,  the  muscularis  mucosce. 

The  sub-mucous  coat  is  thicker  than  the  foregoing,  and  consists  of 
loose  connective-tissue,  with  the  acini  of  small  compound  tubular 
mucous  glands  imbedded  in  it.  The  ducts  pierce  the  muscularis 
mucosae  to  open  on  the  inner  surface  of  the  tube. 

The  muscular  coat  consists  of  an  inner,  thicker,  circular,  and  an  outer, 
thinner,  longitudinal  layer  of  non-striped  muscle.  In  man,  the  upper 
third  of  the  gullet  consists  of  striped  muscular  fibres.  Outside  the 
muscular  coat  is  a  layer  of  fibrous  tissue  with  elastic  fibres. 


MOVEMENTS   OF  THE   STOMACH.  309 

As  in  the  intestine,  there  are  two  plexuses  of  nerves  with  ganglia; 
one  in  the  sub-mucous  coat  and  the  other  between  the  two  muscular 
coats.  Blood-vessels  and  numerous  lymphatics  lie  in  the  mucous  and 
sub-mucous  coats.] 

157.  Movements  of  the  Stomach. 

When  the  stomach  is  empty,  the  great  curvature  is  directed  down- 
wards and  the  lesser  upwards ;  but  when  the  stomach  is  fuU,  it  rotates  on 
an  axis  running  horizontally  through  the  pylorus  and  cardia,  so  that  the 
great  curvature  appears  to  be  directed  to  the  front  and  the  lesser  back- 
wards. 

Arrangement  of  the  Muscular  Fibres. — The  non-striped  muscular 
fibres  of  the  stomach  are  arranged  in  three  directions  or  layers,  an  outer 
longitudinal  continuous  with  those  of  the  oesophagus.  This  layer  is 
best  developed  along  the  curvatures,  especially  the  lesser.  At  the 
pylorus  the  fibres  form  a  thick  layer,  and  become  continuous  with  the 
longitudinal  fibres  of  the  duodenum.  The  circular  fibres  form  a  com- 
plete layer,  but  at  the  pylorus  they  are  well  marked  and  constitute 
the  pyloric  sphincter-muscle,  or  valve ;  whilst  at  the  cardia  (inlet), 
such  a  muscular  ring  is  absent  (Gianuzzi).  The  innermost  oblique  or 
diagonal  layer  is  incomplete. 

The  movements  of  the  stomach  are  of  two  kinds  : — (1.)  The  rotatory 
or  churning  movements,  whereby  the  parts  of  the  wall  of  the  stomach 
lying  in  contact  with  the  contents  or  ingesta  glide  to  and  fro  with  a 
slow  rubbing  movement.  Such  movements  seem  to  occur  periodically, 
every  period  lasting  several  minutes  (Beaumont).  By  these  move- 
ments the  contents  are  moistened  with  the  gastric  juice,  while  the 
masses  of  food  are  partly  broken  down.  The  formation  of  hair-balls  in 
the  stomach  of  dogs  and  oxen  indicates  that  such  rotatory  movements 
of  the  contents  of  the  stomach  take  place.  (2.)  The  other  kiad  of 
movement  consists  in  a  periodically  occurring  peristalsis,  whereby,  as 
with  a  pusli,  the  portions  of  the  contents  of  the  stomach  first  dissolved 
are  forced  iato  the  duodenum.  They  begin  after  a  quarter  of  an  hour 
(Busch),  and  recur  until  about  five  hours  after  a  meal  (Beaumont). 
This  peristalsis  is  most  pronounced  towards  the  pyloric  end,  and  the 
muscles  of  the  pyloric  sphincter  relax  to  allow  the  contents  to  pass 
into  the  duodenum.  According  to  Riidinger,  the  longitudinal  mus- 
cular fibres,  when  they  contract,  especially  when  the  pyloric  end  is 
filled,  may  act  so  as  to  dilate  the  pylorus. 

The  strongly  muscular  walls  of  the  stomach  of   grain-eating  birds  effect  a  tritura- 
tion of  the  food.      The  mechanical  force  thereby  exerted  was  often  experimented 


310  INFLUENCE   OF   NERVES   ON  THE   STOMACH. 

upon  by  the  older  jiliysiologists,  who  found  that  glass  balls  and  lead  tubes,  which 
could  be  compressed  only  by  a  weight  of  40  kilos. ,  were  broken  or  compressed  in  the 
stomach  of  a  turkey. 

Influence  of  Nerves  on  the  Movements. — [The  stomach  is  supplied  by 
the  vagi  and  by  the  sympathetic,  the  right  vagus  being  distributed  to 
the  posterior  surface,  and  the  left  to  the  anterior  surface,  of  the 
stomach.]  The  ganglionic  plexus  of  nerve-fibres  and  nerve-cells  (Auer- 
hach's),  which  lies  between  the  muscular  coats  of  the  stomach,  must  be 
regarded  as  its  proper  motor  centre,  and  to  it  motor  impulses  are  con- 
ducted by  the  vagi.  Section  of  both  vagi  does  not  abolish,  but  it 
diminishes  the  movements  of  the  stomach.  The  muscular  fibres  of 
the  cardia  may  be  excited  to  action,  or  their  action  inhibited  by  fibres 
which  run  in  the  vagus  (Nn.  constrictores,  et  dilatator  cardise),  (v. 
Openchowski).  [If  the  vagi  be  divided  in  the  neck,  there  is  a  short 
temporary  spasmodic  contraction  of  the  cardiac  aperture.  On  stimulat- 
ing the  peripheral  end  of  the  vagus  with  electricity,  after  a  latent 
period  of  a  few  seconds,  the  cardiac  end  contracts,  more  especially  if 
the  stomach  be  distended,  but  the  movements  are  slight  if  the  stomach 
be  empty.] 

Stimulation  of  the  coeliac  plexus  causes  movements  in  the  stomach  of 
ruminants  (Eckhard),  perhaps  indirectly  through  the  effect  upon  the 
blood-vessels. 

Local  electrical  stimulation  of  the  surface  of  the  stomach  causes  circular  constric- 
tions of  the  organ,  which  disappear  very  gradually,  while  the  movement  is 
often  propagated  to  other  parts  of  the  gastric  wall.  When  heated  to  25°C.,  the 
excised  empty  stomach  exhibits  movements  (Calliburces).  Injury  to  the  pedunculi 
cerebri,  optic  thalamus,  medulla  oblongata,  and  even  to  the  cervical  part  of  the 
spinal  cord,  according  to  Schiftj  causes  paralysis  of  the  vessels  of  certain  areas  of 
the  stomach,  resulting  in  congestion  and  subsequent  haemorrhage  into  the  mucous 
membrane. 

[It  is  no  uncommon  occurrence  to  find  haemorrhage  into  the  gastric  mucous 
membrane  of  rabbits,  after  they  have  been  killed  by  a  violent  blow  on  the  head.] 


158.  Vomiting. 

Mechanism. — Vomiting  is  caused  by  contraction  of  the  walls  of  the 
stomach,  whereby  the  pyloric  sphincter  is  closed.  It  occurs  most 
easily  when  the  stomach  is  distended — (dogs  usually  greatly  distend 
the  stomach  by  swallowing  air  before  they  vomit) ;  it  readily  occurs 
in  infants,  in  wdiom  the  cul  de  sac  at  the  cardia  is  not  developed. 
It  is  quite  certain  that  in  children,  this  vomiting  occurs  through  con- 
traction of  the  walls  of  the  stomach  without  the  spasmodic  action  of 
the  abdominal  walls.  When  the  vomiting  is  violent,  the  abdominal 
muscles  act  energetically.     [The  act  of  vomiting  is  generally  preceded 


VOMITING.  311 

by  a  feeling  of  nausea,  and  usually  there  is  a  rush  of  saliva  into  the 
mouth,  caused  by  a  reflex  stimulation  of  aff'erent  fibres  in  the  gastric 
branches  of  the  vagus,  the  efferent  nerve  being  the  chorda  tympani. 
After  this  a  deep  inspiration  is  taken,  and  the  glottis  closed,  so  that 
the  diaphragm  is  firmly  pressed  downwards  against  the  abdominal  con- 
tents, and  it  is  kept  contracted ;  the  lower  ribs  arc  pulled  in.  The 
diaphragm  being  kept  contracted  and  the  glottis  closed,  a  violent 
expiratory  effort  is  made,  so  that  the  contraction  of  the  abdominal 
muscles  acts  upon  the  abdominal  contents,  the  stomach  being  forcibly 
compressed.  The  cardiac  orifice  is  opened  at  the  same  time,  and  the 
contents  of  the  stomach  are  ejected.  The  chief  agent  seems  to  be  the 
abdominal  compression,  but  the  walls  of  the  stomach  also  help,  though 
only  to  a  slight  extent.] 

The  contraction  of  the  walls  of  the  stomach,  which  causes  a  general  diminution 
of  the  gastric  cavity,  is  not  a  true  antiperistalsis,  as  can  be  seen  in  the  stomach 
when  it  is  exposed  (Galen).  The  cardia  is  opened  by  the  longitudinal  muscular 
fibres  (Schiflf)  which  pull  towards  the  lower  orifice  of  the  oesophagus,  so  that 
when  the  stomach  is  full  they  must  act  as  dilators.  The  act  of  vomiting  is  preceded 
by  a  ructus-like  dilating  movement  of  the  intra-thoracic  part  of  the  oesophagus, 
which  is  caused  thus: — The  glottis  is  closed,  inspiration  occurs  suddenly  and 
violently,  whereby  the  oesophagus  is  distended  by  gases  proceeding  from  the 
stomach  (Liittich).  The  larynx  and  hyoid  bone  by  the  combined  action  of  the 
geniohyoid,  sternohyoid,  sternothyroid,  and  thyrohyoid  muscles  are  forcibly  pulled 
forwards,  so  that  tlie  air  passes  from  the  pharynx  downwards  into  the  upper 
section  of  the  oesophagus  (Landois).  If  the  abdominal  walls  contract  suddenly, 
and  if  this  sudden  impulse  be  aided  by  the  movements  of  the  stomach  itself,  the 
contents  of  the  stomach  are  forced  outwards.  During  continued  vomiting,  anti- 
peristalsis  of  the  duodenum  may  occur,  whereby  bile  passes  into  the  stomach, 
and  becomes  mixed  with  its  contents. 

Children,  in  whom  the  fundus  is  absent,  vomit  more  easily  than  adults.  The 
capacity  of  the  stomach  of  a  new-born  child  is  35-43  cubic  centimetres;  after  14 
days,  153-160  c.c. ;  at  2  years,  740  c.c. 

Magendie  was  of  opinion  that  the  abdominal  muscles  alone  were  concerned  in 
vomiting,  as  he  found  that  vomiting  occurred  when  he  replaced  the  stomach  by  a 
bag.  This  was  much  too  crude  an  experiment.  But  it  only  succeeds  when  the 
lowest  part  of  the  oesophagus  has  been  removed  (Fantini,  Schiif).  The  view  of 
Gianuzzi,  that  the  abdominal  muscles  are  the  chief  factor,  because  animals  poisoned 
with  curara — in  whom  these  muscles  are  paralysed,  but  not  the  walls  of  the 
stomach — cannot  vomit,  is  too  wide  a  deduction. 

Influence  of  Nerves. — The  centre  for  the  movements  concerned  in 
vomiting  lies  in  the  medulla  oblongata,  and  is  in  relation  with  the 
respiratory  centre,  as  is  shown  by  the  fact,  that  nausea  may  be  over- 
come by  rapid  and  deep  respirations.  In  animals,  vomiting  may  be 
inhibited  by  vigorous  artificial  respiration.  On  the  other  hand,  the 
administration  of  certain  emetics  prevents  the  occurrence  of  apno^a. 

The  act  of  vomiting  is  most  easily  excited  (chemically  or  mechani- 
cally) by  stimulation  of  the  centripetal  or  afferent  nerves  of  the  mucous 
membrane  of  the  soft  palate,  pharynx,  root  of  the   tongue  (glosso- 


312  MOVEMENTS   OF   THE    INTESTINE. 

pharyngeal  nerve),  stomacli,  and  further,  by  stimulation  of  the  uterus 
(pregnancy),  intestine  (inflammation  of  the  abdomen),  urinary  apparatus 
(passing  a  renal  calculus),  and  also  by  direct  stimulation  of  the  vomiting 
centre. 

Vomiting  produced  by  the  thought  of  something  disagreeable  appears  to  be 
caused  by  the  conduction  of  the  excitement  from  the  cerebrum  to  the  vomiting 
centre.  Vomiting  is  very  common  in  diseases  of  the  brain.  Section  of  both  vagi 
prevents  vomiting. 

Emetics  act  (l)  partly  by  mechanically  or  chemically  stimulating  the  ends  of 
the  centrix^etal  (afferent)  nerves  of  the  mucous  membrane.  Tickling  the  fauces, 
touching  the  surface  of  the  exposed  stomach  (dog);  and  many  chemical  emetics — 
e.g.,  cupric  and  zinc  sulphate  and  other  metallic  salts — act  in  this  way.  (2)  Other 
substances  cause  vomiting  when  they  are  introduced  into  the  blood  (without  being 
first  introduced  into  the  stomach),  and  act  directly  upon  the  vomiting  centre,  e.g., 
apomorphin.  (3)  Lastly,  there  are  some  substances  which  act  in  both  ways, 
e.g.,  tartar  emetic.  Emetics  may  also  remove  mucus  from  the  lungs,  and  in  this 
case  it  is  probable  that  the  emetic  acts  upon  the  respiratory  centre,  and  so  favours 
the  respirations.  [According  to  Lauder  Brunton,  cupric  sulphate  acts  even  when 
injected  into  the  blood.] 

Vomiting  is  analogous  to  the  process  of  rumination  in  animals  that  chew  the 
cud.     Some  persons  can  empty  their  stomach  in  this  way. 

159.  Movements  of  the  Intestine. 

Peristalsis. — The  best  example  of  peristaltic  movements  is  afforded 
by  the  small  intestine ;  the  progressive  narrowing  of  the  tube  pro- 
ceeds from  above  downwards,  thus  propelling  the  contents  before  it. 
Frequently  after  death,  or  when  air  acts  freely  upon  the  gut,  w^e  may 
observe  that  the  peristalsis  develops  at  various  parts  of  the  intestine 
simultaneously,  whereby  the  loops  of  intestine  present  the  appearance 
of  a  heap  of  worms  creeping  amongst  each  other.  The  advance  of  new 
intestinal  contents  again  increases  the  movement.  In  the  large 
intestine,  the  movements  are  more  sluggish  and  less  extensive.  The 
peristaltic  movements  may  be  seen  and  felt  when  the  abdominal  walls 
are  very  thin,  and  also  in  hernial  sacs.  They  are  more  lively  in  vegetable 
feeders  than  in  carnivora.  The  peristalsis  is  perhaps  conducted  directly 
through  the  muscular  substance  itself  (as  in  the  heart  and  ureter — 
Engelmann). 

Method  of  Observation.— Open  the  abdomen  of  an  animal  under  a"6  p.e.  saline 
solution  to  prevent  the  exposure  of  the  gut  to  air  (Sanders,  and  Braam-Houckgeest). 

The  ileo-eolic  valve  (Bauhin's  valvej  1579,  known  to  Eondelet  in 
1554),  as  a  rule,  prevents  the  contents  of  the  large  intestine  from  pass- 
ing backwards  into  the  small  intestine.  The  movements  of  the 
stomach  and  intestine  cease  during  sleep  (Busch). 

However,  when  fluid  is  slowly  introduced  into  the  rectum  through  a  tube,  it 
may  pass  upwards  into  the  intestine,  and  even  go  through  the  ileo-colic  valve  into 
the  small  intestine. 


EXCRETION   OF  F^CAL  MATTER.  31 3 

Muscarin  excites  very  lively  peristalsis  of  the  intestines,  which  may  be  set  aside 
by  atropin  (Schmiedeberg  and  Koppe). 

Pathological. — When  any  condition  excites  an  acute  inflammation  of  the  intes- 
tinal mucous  membrane,  catan-h  is  rapidly  produced,  and  very  strong  contractions 
of  the  inflamed  parts  filled  with  food,  take  place.  When  these  parts  of  the  gut 
become  empty,  the  movements  are  not  stronger  than  normal.  If  new  material 
passes  into  the  inflamed  part,  the  peristalsis  recurs,  and  is  more  lively  than  normal, 
and  the  result  is  diarrhoea  (Nothnagel).  Sometimes,  a  greatly  contracted  part  of 
the  small  intestine  is  pushed  into  the  piece  of  gut  directly  continuous  with  it, 
giving  rise  to  invagination  or  intussusception. 

Antiperistalsis — '.e.,  a  movement  which  sets  in  and  travels  in  an  upward 
direction  towards  the  stomach,  does  not  occur  normally.  That  such  a  condition 
takes  place  has  been  inferred  from  the  fact,  that  in  cases  where  the  intestine  is 
occluded  (Ileus)  fajcal  matter  is  vomited.  The  most  recent  experiments  of 
Nothnagel  throw  doubts  upon  this  view,  as  he  failed  to  observe  antiperistalsis  in 
cases  where  the  intestine  was  occluded  artificially.  The  fsecal  odour  of  the  ejecta 
may  result  fi'om  the  x^rolonged  retention  of  the  material  within  the  small  intestine. 


160.  Excretion  of  Fsecal  Matter. 

The  contents  of  the  small  intestine  remain  in  it  about  three  hours, 
and  about  twelve  hours  in  the  large  intestine,  where  they  become  less 
watery.  The  contents  assume  the  characters  of  faeces,  and  become 
"formed"  in  the  lower  part  of  the  great  intestine.  The  faeces  are 
gradually  carried  along  by  the  peristaltic  movement,  until  they  reach  a 
point  a  little  above  that  part  of  the  rectum  which  is  surrounded  by 
both  sphincters  ;  the  internal  sphincter  consisting  of  non-striped,  and 
the  external  of  striped  muscle. 

Immediately  after  the  faeces  have  been  expelled,  the  external 
sphincter  (Fig.  129,  S,  and  Fig.  130)  usually  contracts  vigorously,  and 
remains  in  this  condition  for  some  time.  Afterwards  it  relaxes,  when 
the  elasticity  of  the  parts  surrounding  the  anal  opening,  particularly  of 
the  two  sphincters,  suffices  to  keep  the  anus  closed.  In  the  interval 
between  two  evacuations,  there  does  not  seem  to  be  a  continued  tonic 
contraction  of  the  sphincters.  As  long  as  the  faeces  lie  above  the 
rectum,  they  do  not  excite  any  conscious  sensations,  but  the  sensation 
of  requiring  to  go  to  stool  occurs,  when  the  faeces  pass  into  the  rectum. 
At  the  same  time,  the  stimulation  of  the  sensory  nerves  of  the  rectum 
causes  a  reflex  excitement  of  the  sphincters.  The  centre  for  these 
movements  (Budge's  centrum  anospinale)  lies  in  the  lumbar  region  of 
the  spinal  cord ;  in  the  rabbit,  between  the  sixth  and  seventh,  and  in 
the  dog,  at  the  fifth  lumbar  vertebra  (Masius), 

In  animals,  whose  spinal  cord  is  divided  above  the  centre,  a  slight  touch  in  the 
region  of  the  anus  causes  this  orifice  to  contract,  but  after  this  lively  reflex  con- 
traction, the  sphincters  relax  again,  and  the  anus  may  remain  open  for  a  time. 
This  occurs,  because  the  voluntary  impulses  which  proceed  from  the  brain  to  cause 
the  contraction  of  the  external  sphincter  are  absent.     Landois  observed,  that  in 


314 


EXCRETION   OF  E^CAL  MATTER. 


2 
Fig.  129. 

The  Perinseum  and  its  Muscles — 1,  Anus  ;  2,  coccyx ;  3,  tuberosity ;  4,  sciatic 
ligament ;  5,  cotyloid  cavity ;  B,  bulbo-cavernosus  muscle  ;  Ts,  superficial 
transverse  perineal  muscle ;  F,  fascia  of  the  deep  transverse  perineal  muscle ; 
J,  ischio-cavernosus  muscle ;  M,  obturator  internus  ;  S,  external  anal  sphinc- 
ter ;  L,  levator  ani ;  P,  pyriformis  (Henle). 

dogs  with  the  posterior  roots  of  their  lower  lumbar  and  sacral  nerves  divided  j 
the  anus  remained  open,  and  not  unfrequently  a  mass  of  fseces  remained  half 
ejected.  As  the  sensibility  of  the  rectum  and  anus  was  abolished  in  these  animals, 
the  sphincters  could  not  contract  reflexly,  nor  could  there  be  any  voluntary  con- 
traction of  the  sphincters. 

The  external  sphincter  can  be  contracted  voluntarily  from  the  cerebrum, 
like  any  voluntary  muscle,  but  the  closure  can  only  be  effected  up  to  a 
certain  degree.  When  the  pressure  from  above  is  very  great,  the  energetic 
peristalsis  at  last  overcomes  the  strongest  voluntary  impulses.  Stimula- 
tion of  the  peduncles  of  the  cerebrum  and  of  the  spinal  cord  below  this 
point,  causes  contraction  of  the  external  sphincter. 

Defsecation. — The  evacuation  of  the  fseces,  which  in  man  usually  occurs 
at  certain  times,  begins  with  a  lively  peristalsis  of  the  large  intestine, 
which  passes  downwards  to  the  rectum.     In  order  that  the  mass  of 


DEFiECATION. 


315 


faeces  may  not  excite  reflexly  the  sphincter-muscles,  in  consequence  of 
mechanical  stimulation  of  the  sensory  nerves  of  the  rectum,  there  seems 
to  be  an  inhibitory  centre  for  the  reflex  action  of  the  sphincters,  which  is 
set  in  action,  owing,  as  it  appears,  to  voluntary  impulses.  Its  seat 
is  in  the  brain;  Masius  thinks  it  is  in  the  optic  thalami,  from  whence 
fibres  pass  through  the  peduncles  of  the  cerebrum  to  the  lumbar 
part  of  the  spinal  cord.  When  this  inhibitory  apparatus  is  in  action, 
the  fiscal  mass  passes  through  the  anus,  without  causing  it  to  close 
reflexly. 

The  strong  peristalsis  which  precedes  defsecation  can  be  aided,  and  to 
a  certain  degree,  excited  by  voluntary,  short,  movements  of  the  external 
sphincter  and  levator  ani,  whereby  the  plexus  myentericus  of  the  large 
intestine    is    stimulated   mechanically,   thus    causing   lively  peristaltic 


Fig.  130. 
Levator  ani  and  Sphincter  ani  externus. 

movements  in  the  large  intestine.  The  expulsion  of  the  faeces  is  also 
aided  by  the  pressure  of  the  abdominal  muscles,  and  most  efficiently 
when  a  deep  inspiration  is  taken,  so  as  to  fix  the  diaphragm,  whereby 
the  abdominal  cavity  is  diminished  to  the  greatest  extent.     The  soft 


316  INFLUENCE   OF   NERVES   ON   THE   INTESTINE. 

parts  of  the  floor  of  the  pelvis  during  a  strong  efl'ort  at  stool,  are  driven 
downwards  in  the  form  of  a  cone,  causing  the  mucous  membrane  of  the 
anus,  which  contains  much  venous  blood,  to  be  everted.  The  function  of 
the  levator  ani  (Figs.  129, 130)  is,  to  raise  voluntarily  the  soft  parts  of  the 
floor  of  the  pelvis,  and  to  pull  the  anus  to  a  certain  extent  upwards  over 
the  descending  faecal  mass.  At  the  same  time,  it  prevents  the  distension 
of  the  pelvic  fascia.  As  the  fibres  of  both  levatores  converge  below  and 
become  united  with  the  fibres  of  the  external  sphincter,  they  aid  the 
latter,  during  energetic  contraction  of  the  sphincter;  or,  as  Hyrtl  puts  it, 
the  levatores  are  related  to  the  anus,  like  the  two  cords  of  a  tobacco 
pouch.  During  the  periods  between  the  evacuation  of  the  gut,  the 
faeces  appear  only  to  reach  the  lower  end  of  the  sigmoid  flexure.  As  a 
rule,  from  thence  downwards,  the  rectum  is  normally  devoid  of  faeces.  It 
seems  that  the  strong  circular  fibres  of  the  muscular  coat,  which  N6laton 
has  called  sphincter  ani  tertius,  when  they  are  well  developed,  contract 
and  prevent  the  entrance  of  the  faeces.  When  the  tendency  to  the 
evacuation  of  the  rectum  is  very  pressing,  the  anus  may  be  closed  more 
firmly  from  without,  by  energetically  rotating  the  thigh  outwards,  and 
contracting  the  muscles  of  the  gluteal  region. 

161.  Influence  of  Nerves  on  the  Intestinal 
Movements. 

Auerbach's  Plexus. — The  intestinal  canal  contains  an  automatic  motor 
centre  within  its  walls — the  i^lexus  myentericus  of  Auerbach — which  lies 
between  the  longitudinal  and  circular  muscular  fibres  of  the  gut.  It  is 
this  plexus  which  enables  the  intestine  when  cut  out  of  the  body  to 
execute,  apparently  spontaneously,  movements  for  some  time. 

[Structure. — The  plexus  of  Auerbach  consists  of  non-meduUated  nerve-fibres 
which  form  a  dense  plexus,  groups  of  ganglion  cells  occurring  at  the  nodes  (Fig. 
131).  A  similar  plexus  extends  throughout  the  whole  intestine  between  the 
longitudinal  and  circular  muscular  coats  from  the  oesophagus  to  the  rectum. 
Branches  are  given  off  to  the  muscular  bundles.  A  similar,  but  not  so  rich  a 
pjlexus  lies  in  the  sub-mucous  coat,  Meissner's  plexus,  which  gives  branches  to 
supply  the  muscularis  mucosae,  the  smooth  muscular  fibres  of  the  ^^lli,  and  the 
glands  of  the  intestine  (Fig.  132).] 

1.  If  this  centre  is  not  afi'ected  by  any  stimulus,  the  movements  of 
the  intestine  cease — comparable  to  the  condition  of  the  medulla 
oblongata  in  apnoea  (Sig.  Mayer  and  v,  Basch),  The  same  is  true — 
just  as  in  the  case  of  the  respiration — during  intra-uterine  life,  in  con- 
sequence of  the  foetal  blood  being  well  supplied  with  0.  This  condition 
may  be  termed  aperistakis.  It  also  occurs  during  sleep,  perhaps  on 
account  of  the  greater  amount  of  0  in  the  blood  during  that  state. 


AUERBACH   AND   MEISSNER'S   PLEXUSES. 


317 


Fig.  131. 

Plexus  of  Aiierbach,  pi'epared  from  the  small  intestine  of  a  dog,  by  the  action  of 
gold  chloride.  The  uerve-cells  are  shown  at  the  nodes,  while  the  fibrils  pro- 
ceeding from  the  ganglia,  and  the  anastomosing  fibres,  lie  between  the 
muscular  bundles. 


Fig.  132. 

Plexus  of  Meissner — a,  ganglia;  h,  anastomosing  fibres;  c,  artery;  d,  vaso-motor 
nerve-fibres  accompanying  c. 


2.  When  blood  containing  the  normal  amount  of  blood-gases  passes 
through  the  intestinal  blood-vessels,  the  quiet  peristaltic  movements  of 


318  INFLUENCE   OF  BLOOD   ON   THE   INTESTINE. 

health  occur  (euperistalsis)  provided  no  other  stimulus  be  applied  to  the 
intestine. 

3.  All  stimuli  applied  to  the  plexus  myentericus  increase  the  peri- 
stalsis, which  may  become  so  very  violent  as  to  cause  evacuation  of 
the  contents  of  the  large  gut,  and  may  even  produce  spasmodic  con- 
traction of  the  musculature,  of  the  intestine.  This  condition  may  be 
termed  dysperistalsis,  corresponding  to  dyspnoea.  The  condition  of  the 
blood  flowing  through  the  intestinal  vessels  has  a  most  important  effect 
on  the  peristaltic  movements. 

Condition  of  the  Blood. — Dysperistalsis  may  be  produced  by  (a)  interrupting 
the  circulation  of  blood  in  the  intestines,  no  matter  whether  anaemia  (as  after 
compressing  the  aorta— Schiff,)  or  venous  hypersemia  be  produced.  The  stimu- 
lating condition  is  the  want  of  0,  i.e.,  the  increase  of  CO2.  Very  slight  dis- 
turbance in  the  intestinal  blood-vessels,  e.g.,  venoiis  congestion  after  copious 
transfusion  into  the  veins,  whereby  the  abdominal  and  portal  veins  become 
congested,  causes  increased  peristalsis.  The  intestines  become  nodulated  at 
one  part  and  narrow  at  another,  and  involuntary  evacuation  of  the  fseces 
takes  place  when  there  is  congestion,  owing  to  the  plugging  of  the  intestinal 
blood-vessels  when  blood  from  another  species  of  animal  is  used  for  trans- 
fusion (p.  202— Landois).  The  marked  peristalsis  which  occurs  on  the  approach 
of  death  is  undoubtedly  due  to  the  derangements  of  the  circulation,  and  the  con- 
sequent alteration  of  the  amount  of  gases  in  the  blood  of  the  intestine.  The  same 
is  true  of  the  increased  movements  of  the  intestines  which  occur  as  a  result  of 
psychical  excitement,  e.g.,  grief.  The  stimiilus,  in  this  case,  passes  from  the 
cerebrum  through  the  medulla  oblongata  (vaso-motor  centre)  to  the  intestinal 
nerves  and  causes  anaemia  of  the  intestine,  (corresponding  to  the  palor  occurring 
elsewhere).  When  the  normal  condition  of  the  circulation  is  restored,  the  peri- 
stalsis diminishes.  (b)  Direct  stimulation  of  the  intestine,  conducted  to  the 
plexus  myentericus,  causes  dysperistalsis ;  direct  exposure  of  the  intestines  to  the 
air  (stronger  when  CO2  or  CI  is  present)— -the  introduction  of  various  irritating 
substances  into  the  intestine — increased  filling  of  the  intestine  when  there  is  any 
difficulty  in  emptying  the  gut  (often  in  man) — direct  stimulation  of  various  kinds 
(also  inflammation),  all  act  upon  the  intestine,  either  from  without  or  from 
within.  Induction  shocks  applied  to  a  loop  of  intestine  in  a  hernial  sac  cause 
lively  peristalsis  in  the  hernia.  The  intestinal  movements  are  favoured  by  heat, 
and  cease  below  19°C.  (Horwath). 

4.  The  continued  application  of  strong  stimuli  causes  the  dysperi- 
stalsis to  give  place  to  rest,  owing  to  over-stimulation,  which  may  be 
called  "  intestinal  jparesis,"  or  exhaustion. 

This  condition  is  absolutely  different  from  the  passive  condition  of  the  intestine 
in  aperistalsis.  Continued  congestion  of  the  intestinal  blood-vessels  ultimately 
causes  intestinal  paralysis,  e.g.,  when  transfusion  of  foreign  blood  causes  coagula- 
tion within  these  vessels  (Landois).  Filling  the  blood-vessels  with  "indifferent  " 
fluids,  after  the  peristalsis  has  been  previously  caused  by  compressing  the  aorta, 
also  causes  cessation  of  the  movements  (0.  Nasse).  The  movements  cease  when 
the  intestines  are  cooled  to  19°C.  (Horwath),  while  severe  inflammation  of  the 
intestine  has  a  similar  effect.  Under  favourable  circumstances,  the  intestine  may 
recover  from  this  condition.  Arterial  blood  admitted  into  the  vessels  of  the 
exhausted  intestine  causes  peristalsis,  which  at  first  is  more  vigorous  than  normal. 


INFLUENCE   OF  NERVES   ON   THE  INTESTINE,  319 

5.  The  continued  application  of  strong  stimuli  causes  complete 
paralysis  of  the  intestine,  such  as  occurs  after  violent  peritonitis,  or 
inflammation  of  the  musculature  or  mucous  coat  in  man.  In  this  con- 
dition, the  intestine  is  greatly  distended,  as  the  paralysed  musculature 
does  not  offer  sufficient  resistance  to  the  intestinal  gases  which  are 
expanded  by  the  heat.     This  constitutes  the  condition  of  meteorism. 

Influence  of  Nerves. — With  regard  to  the  nerves  of  the  intestine, 
stimulation  of  the  vagus  increases  the  movements  (of  the  small  intes- 
tine), either  by  conducting  impressions  to  the  plexus  myentericus,  or 
by  causing  contraction  of  the  stomach,  which  stimulates  the  intestine  in 
a  purely  mechanical  manner  (Braam-Houckgeest).  The  splanchnic  is 
(1)  the  inhibitory  nerve  of  the  small  intestine  (Pfliiger),  but  only  as  long 
as  the  circulation  in  the  intestinal  blood-vessels  is  undisturbed,  and  the 
blood  in  the  capillaries  does  not  become  venous  (Sigm.  Mayer,  and 
von  Basch) ;  when  the  latter  condition  occurs,  stimulation  of  the 
splanchnic  increases  the  peristalsis.  If  arterial  blood  be  freely  sup- 
plied, the  inhibitory  action  continues  for  some  time  (0.  Nasse).  Stimu- 
lation of  the  origin  of  the  splanchnics,  of  the  spinal  cord  in  the  dorsal 
region  (under  the  same  conditions),  and  even  when  general  tetanus  has 
been  produced  by  the  administration  of  strychnia,  causes  an  inhibitory 
effect.  0.  Nasse  concludes  from  these  experiments  that  the  splanchnic 
contains — (2)  inhibitory  fibres  which  are  easily  exhausted  by  a  venous 
condition  of  the  blood,  and  also  motor  fibres  which  remain  excitable  for 
a  longer  time,  because  after  death,  stimulation  of  the  splanchnics  always 
causes  peristalsis,  just  like  stimulation  of  the  vagus.  (.3)  The  splanch- 
nic is  also  the  vaso-motor  nerve  of  all  the  intestinal  blood-vessels,  so  that 
it  governs  the  largest  vascular  area  in  the  body.  When  it  is  stimu- 
lated, all  the  vessels  of  the  intestine,  which  contain  muscular  fibres  in 
their  walls,  contract ;  when  it  is  divided,  they  dilate.  In  the  latter 
case,  a  large  amount  of  blood  accumulates  within  the  blood-vessels  of 
the  abdomen,  so  that  there  is  an?emia  of  the  other  parts  of  the  body, 
which  may  be  so  great  as  to  cause  death — owing  to  the  deficient  supply 
of  blood  to  the  medulla  oblongata.  (4)  The  splanchnic  is  the  sensory 
nerve  of  the  intestine,  and  as  such,  under  certain  circumstances,  it  may 
give  rise  to  extremely  painful  sensations. 

As  stimulation  of  the  splanchnic  contracts  the  blood-vessels,  von  Basch  has 
raised  the  question,  whether  the  intestine  does  not  come  to  rest,  owing  to  the  want 
of  the  blood,  which  acts  as  a  stimulus.  But,  when  a  weak  stimulus  is  applied 
to  the  splanchnic,  the  intestine  ceases  to  move  before  the  blood-vessels  contract 
(van  Braam-Houckgeest) ;  it  would  therefore  seem  that  the  stimulation  diminishes 
the  excitability  of  the  plexus  myentericus. 

According  to  Engelmann  and  v.  Brakel,  the  peristaltic  movement  is  chiefly  pro- 
pagated by  direct  muscular  conduction,  as  in  the  heart  and  ureter,  without  the 
intervention  of  any  nerve-fibres. 


320  EFFECT   OF  DRUGS   ON   THE  INTESTINE. 

Effect  of  Drugs. Amongst  the  reagents  which  act  upon  the  intestinal  move- 
ments are  :— (1)  Such  as  diminish  the  excitability  of  the  plexus  myentericus,  i.e., 
which  lessen  or  even  abolish  intestinal  peristalsis,  e.g.,  belladonna.  (2)  Such  as 
stimulate  the  inhibitory  fibres  of  the  splanchnic,  and  in  large  doses  paralyse  them— 
opium,  morphia  (Nothnagel) ;  1  and  2  produce  constipation.  (3)  Other  agents 
excite  the  motor  apparatus — nicotin  (even  causing  spasm  of  the  intestine),  muscarin, 
caffein,  and  many  laxatives,  which  act  as  purgatives.  The  movements  produced  by 
muscarin  are  abolished  by  atropin  (Schmiedeberg  and  Koppe).  These  substances 
accelerate  the  evacuation  of  the  intestine,  and,  owing  to  the  rapid  movement  of  the 
intestinal  contents,  only  a  small  amount  of  water  is  absorbed  ;  so  that  the  evacua- 
tions are  frequently  fluid.  (4)  Amongst  purgatives,  colocynth  and  croton  oil  act  as 
direct  irritants.  With  regard  to  drugs  of  this  sort,  they  seem  to  cause  a  watery 
transudation  into  the  intestine  (C.  Schmidt,  Moreau),  just  as  croton  oil  causes 
vesicles  when  applied  to  the  skin.  (5)  Calomel  is  said  to  limit  the  absorptive 
activity  of  the  intestinal  wall,  and  to  control  the  decompositions  in  the  intestine.  . 
The  stools  are  thin  and  greenish  from  the  admixture  of  bili-verdin.  (6)  Certain 
saline  purgatives— sodium  sulphate,  magnesium  sulphate,  cause  fluid  evacuations  by 
retainino-  the  water  in  the  intestine  (Buchheim) ;  and  it  is  said,  that  if  they  be  injected 
into  the  blood-vessels  of  animals,  they  cause  constipation  (Aubert). 

If  a  crystal  of  a  potash  salt  be  applied  to  the  intestine,  it  causes  a  local  con- 
striction, accompanied  by  lively  movement  extending  about  10  centimetres  above 
where  the  crystal  was  applied.  Soda  salts  are  not  so  powerful,  and  they  seem  to 
act  upon  the  nerves  and  not  upon  the  musculature  (Nothnagel,  K.  Bardeleben). 

[Action  of  Saline  Cathartics.— From  an  extended  investigation  recently 
made  by  Matthew  Hay  on  the  action  of  saline  cathartics,  it  would  appear  certain 
that  a  salt  exerts  a  genuine  excito-secretory  action  on  the  glands  of  the  intestines, 
whilst  at  the  same  time,  in  virtue  of  its  low  diffusibility,  it  impedes  absorption. 
Thus,  between  stimulated  secretion  and  impeded  absorption  there  is  an  accumula- 
tion of  fluid  within  the  canal,  which,  partly  from  ordinary  dynamical  laws,  partly 
from  a  gentle  stimulation  of  the  peristaltic  movements  excited  by  distension, 
reaches  the  rectum  and  results  in  purgation.  Purgation  does  not  ensue  when 
water  is  withheld  from  the  diet  for  one  or  two  days  previous  to  the  administration 
of  the  salt  in  a  concentrated  form.  This  absence  of  effect  is  due  to  a  deficiency  of 
water  in  the  blood,  so  that  the  blood  cannot,  through  the  intestinal  glands,  yield 
enough  fluid  to  the  salt  in  order  to  produce  purgation.  When  a  concentrated 
solution  of  a  salt  is  administered  to  an  animal  whose  alimentary  canal  is  known, 
from  a  few  hours'  preliminary  fasting,  to  be  empty,  but  whose  blood  is  in  a  natural 
state  of  dilution,  the  blood  becomes  rapidly  very  concentrated,  and  reaches  the 
maximum  of  its  concentration  in  from  half  an  hour  to  an  hour  and  a  half; 
within  four  hours  the  blood  has  gradually  returned  to  its  normal  state  of  concen- 
tration without  having  reabsorbed  fluid  from  the  intestine.  It  apparently  recoups 
itself  from  the  tissue-fluids.  After  a  few  days'  abstention  from  water,  the  tissue- 
fluids  are  so  much  diminished  as  not  to  be  able  any  longer  to  recoup  the  blood,  and 
the  blood  itself  gradually  becomes  concentrated;  hence  a  concentrated  saline 
solution  fails  to  excite  any  secretion  when  administered. 

It  is  also  interesting  in  connection  with  saline  cathartics  that  the  salt — sulphate 
of  magnesia  or  sulphate  of  soda— becomes  split  up  in  the  small  intestine,  and  the 
acid  is  more  rapidly  absorbed  than  the  base.  A  portion  of  the  absorbed  acid 
shortly  afterwards  returns  to  the  intestines,  evidently  through  the  intestinal 
glands.  After  the  maximum  of  excretion  of  the  acid  has  been  reached,  the  salt 
begins  very  slowly  and  gradually  to  disappear  by  absorption,  which  is  checked 
only  by  the  occurrence  of  purgation.  The  salt  does  not  purge  when  injected  into 
the  blood,  and  excites  no  intestinal  secretion;  nor  does  it  purge  when  injected 
subcutaneously,  unless  on  account  of  its  causing  local  irritation  of  the  abdominal 
subcutaneous  tissue,  which  acts  reflexly  on  the  intestines,  dilating  their  blood- 
vessels, and  perhaps  stimulating  their  muscular  movements.] 


STRUCTURE   OF  THE   STOMACH. 


321 


162.  Structure  of  the  Stomach. 

structure. — [The  walls  of  the  stomach  consist  of  four  co'ats,  which 
are  from  without  inwards — 

(1)  The  serous  layer,  from  the  peritoneum. 

(2)  The  muscular  layer,  composed  of  three  layers  of  non-striped 

muscular    fibres  —  (a),    longitudinal;     (h),  circular;    (c), 
oblique  (see  p.  309). 

(3)  The  sub-rmicous  layer,   of  loose  connective-tissue,  with  the 

larger  blood-vessels,  lymphatics,  and  nerves. 

(4)  The  imicous  layer.] 

The  well-developed  mucous  membrane  of  the  stomach  is  thrown 
into  a  series  of  folds  or  rugce,  in  the  contracted  condition  of  the 
organ.  With  the  aid  of  a  hand-lens,  it  is  seen  to  be  beset  Avith  small 
irregular  depressions  or  ^j/^s  (Vidius,  1567 — Fig.  133).  Throughout 
its  entire  extent  it  is  covered  by  a  single  layer  of  moderately  tall, 
narrow  cylindrical  epithelium,  which  seems  to  consist  of  mucus-secret- 
ing goblet  cells  (Fig.  135,  d).  The  epithelium  is  sharply  defined  at 
the  cardia  from  the  stratified  epithelium  of  the  oesophagus,  and  also  at 
the  pylorus,  from  the  true  cylindrical  epithelium  with  the  striated  disc  in 
the  duodenum.  [The  cells  in  the  passive  condition  seem  to  consist  of 
two  zones,  an  outer  clear  part,  next  the  lumen  of  the  organ,  consisting 
of  a  substance  (mucigen)  which 
jdelds  mucus,  the  attached  end 
of  the  cell  being  granular.] 
The  oval  nucleus  lies  about  the 
centre  of  the  cells.  Spindle- 
shaped,  nucleated  cells,  probably 
for  replacing  the  others,  are  said 
by  Ebstein  to  occur  at  their 
bases.  All  the  cells  are  open  at 
their  free-ends,  so  that  the  mucus 
is  readily  discharged,  leaving  the 
cells  empty  (F.  E.  Schultze). 
Numerous  tubular  glands  of  two 
distinct  kinds  are  placed  ver- 
tically, like  rows  of  test-tubes,  in 
the  mucous  membrane. 

Fundus-glands. — On  making  a 
vertical  section  of  the  cardiac 
portion  of  the  gastric  mucous 
membrane,  and  submitting  it  to 
microscopic  examination,  it  is  seen  to  consist  of  a  number  of  tubular  glands 


Fig.  133. 

Surface  section  of  tlie  dog's  gastric  muc- 
ous membrane,  showing  the  crater-like 
depressions  or  pits,  it;  a,  the  elevations 
round  ii. 


21 


322 


FUNDUS-GLANDS   OF  THE   STOMACH. 


placed  side  by  side.  These  are  the  fundus-glands  (Heidenhain),  otherwise 
called  peptic,  or  cardiac.  Several  gland-tubes,  which  are  wider  below, 
usually  open  into  the  short  duct  (Fig.  136).  Each  gland  consists  of  a 
structureless  membrana  propria  with  anastomosing  branched  cells  in 
relation  with  it.  The  duct  is  lined  by  a  layer  of  cells  like  those  lining 
the  stomach,  while  the  secretory  part  of  the  tubes  is  lined  throughout 
by  a  layer  of  granular,  short,  small,  polyhedral,  or  columnar  nucleated 
cells.  These  cells  border  the  very  narrow  lumen,  and  were  called 
chief  or  principal  cells  by  Heidenhain;  they  are  also  known  as  central 
cells  (Fig,  134,  II,  a),  or  adelommplious  (adrjXog,  hidden).  At  various 
places,  between  these  cells  and  the  membrana  propria  are  large  oval, 
or  angular,  well-defined  granular,  densely  reticulated,  nucleated  cells, 
the  parietal   cells   of   Heidenhaii ,  or  the  delomoiphous  cells  of  Eollett 


Fig.  134. 

I,  Transverse  section  of  a  duct  of  a  fundus-gland— a,  membrana  propria;  b,  mucus- 
secreting  goblet  cells;  c,  adenoid  interstitial  substance.  II,  Transverse  sec- 
tion of  a  fundus-gland — a,  chief  cells;  h,  parietal  cells;  r,  adenoid-tissue 
between  tlie  gland-tubes ;  c,  divided  capillaries. 

(Fig.  134,  II,  h).  They  are  most  numerous  in  the  neck  of  the  glands, 
and  least  so  in  the  deep  blind  end  of  the  tubes.  These  cells  are 
stained  deeply  by  osmic  acid  and  aniline  blue,  so  that  they  are  readily 
distinguished  from  the  other  cells.  They  bulge  out  the  membrana 
propria  of  the  gland  opposite  where  they  are  placed.  The  parietal 
cells  in  man  are  said  to  reach  to  the  lumen  of  the  gland-tubes  (Stohr). 
Isolated  cells  are  sometimes  found  under  the  epithelium  of  the  surface 
of  the  stomach  (Heidenhain),  and  occasionally  in  individual  pyloric 
glands  (Stohr).  The  fundus-glands  are  most  numerous  (about  5 
millions,  according  to  Sappey),  and  are  of  considerable  size  in  the 
fundus. 

2.  The  Pyloric  Glands  occur  only  in  the   region  of  the  pylorus, 


PYLORIC  GLANDS  OF  THE   STOMACH. 


323 


where  the  mucous  membrane  is  more  yellowish-white  in  colour 
(Fig.  135,  A).  These  glands  are  generally  branched  at  their  lower 
ends,  so  that  several  tubes  open  into  a  single  duct  [which,  in  contra- 
distinction to  the  duct  of  the  other  glands,  is  wide  and  long,  extending 
often  to  half  the  depth  of 


the  mucous  membrane. 
The  dud  is  lined  by  epi- 
thelium like  that  lining 
the  stomach,  while  the 
secretory  part  is  lined  by 
a  single  layer  of  short, 
finely  granular,  columnar 
cells,  whose  secretion  is 
quite  different  from  that 
of  the  cells  Uning  the  duct. 
The  lumen  is  well-defined. 
Nussbaum  has  occasionally 
found  other  cells,  which 
stain  deeply  with  osmic 
acid,  between  the  bases 
of  these.  Ebsteiu  regards 
these  cells  as  forming 
pepsin.  It  is  to  be  remem- 
bered that  the  appearance 
of  the  cells  differs  ac- 
cording to  their  state  of 
physiological  activity 
(Figs.  137  and  138).  When 
they  are  exliausted  they 
are  smaller  and  more  gran- 
vdar,  owing  to  the  denser 
reticulation  of  their  net-work ;  at  any  rate,  they  are  granular  in  pre- 
parations hardened  in  alcohol  (Fig.  138).] 

Muscularis  Mucosae. — The  glands  are  supported  by  very  delicate  connective- 
tissue  mixed  with  adenoid-tissue  (Fig.  134).  Below  this  are  two  layers,  circular 
and  longitudinal,  of  non-striped  muscle,  the  muscularis  mucosce,  and  from  it  fine 
processes  of  smooth  muscular  fibres  pass  up  between  groups  of  the  glands  towards 
the  free  epithelial  surface  of  the  gastric  mucous  membrane.  These  muscular 
processes  are  said  to  be  concerned  in  emptying  the  glands.  [In  the  gastric  mucous 
membrane  of  the  cat,  there  is  a  clear  homogeneous  layer  which  is  stained  red  by 
picrocannine,  and  placed  immediately  internal  to  the  muscularis  mucosa?.  It  is 
pierced  by  the  processes  passing  from  the  muscularis  mucosae.] 

Masses  of  adenoid-tissue  occur  in  the  mucous  membrane,  especially  near  the 
pylorus,  constituting  lymph-foUicks,  which  are  comparable  to  the  solitary  glands 
of  the  small  intestme. 


Fig.  135. 

A,  Isolated  pyloric  gland ;  d,  isolated  goblet 

cells. 


324 


LYMPHATICS  AND  NERVES  OP  THE  STOMACH. 


The  Lymphatics  are  numerous,  and  begin  close  under  the  epithelium  by 
dilated  extremities  or  loops  (Fig.  136,  d);  they  run  vertically,  and  anastomose  in  the 
mucosa  between  the  gland-tubes,  which  they  enveloxse  in  sinus-like  spaces.  They 
join  large  trunks  in  the  mucosa ;  another  plexus  of  large  vessels  exists  in  the  sub- 
mucosa  (Loven). 

[The  Nerves. — A  plexus  of  non-meduUated  nerve-fibres  and  a  few  ganglion  cells 


Fig.  136. 

Vertical  section  of  the  gastric  mucous  membrane— (/  g,  jjits  on  the  surface;  p,  neck 
of  fundus-glands  opening  into  a  duct,  g;  x,  parietal,  and  y,  chief  cells;  a,  v,  c, 
artery,  vein,  capillaries;  d,  d,  lymphatics,  emptying  into  a  large  truuk,  e. 
(Partly  schematic). 

exist  in  the  muscular  coat    (Auerbach's),   and   another  (Meissner's)  in  the  sub- 
mucosa.] 

The  Blood-vessels  are  very  numerous.  Small  arterial  branches,  a,  run  in  the 
sub-mucosa  and  ascend  between  the  glands  to  form  a  longitudinal  capillary  net-work, 
c  c,  which  forms  a  narrow  net-work  under  the  epithelium,  and  between  its  meshes 
the  gland-ducts  open  {g).  The  veins  gradually  collect  from  this  horizontal 
capillary  net-work  ami  run  towards  the  large  veins  of  the  sub-mucosa,  v. 


THE   GASTRIC   JUICE,  325 

163.  The  Gastric  Juice. 

Properties — The  gastric  juice  is  a  tolerably  clear  colourless  fluid, 
with  a  strong  acid  reaction,  sour  taste,  and  peculiar  characteristic  odour; 
it  rotates  the  plane  of  polarised  light  to  the  left  (Hoppe-Seyler).  It  is 
not  rendered  turbid  by  boiling,  and  resists  putrefaction  for  a  long  time. 
Its  specific  gravity  =  1002-5  (dog,  1005),  and  it  contains  only  i  p.c.  of 
solid  constituents.  The  quantity  of  gastric  juice  secreted  in  24  hours 
was  estimated  by  Beaumont,  from  observations  upon  Alexis  St.  Martin, 
who  had  a  gastric  fistula  (1834) — at  only  180  grms.  daily  (!);  by 
Grunewald  (1853),  in  a  similar  case,  as  equal  to  26-4  p.c.  of  the  body- 
weight;  while  Bidder  and  Schmidt  (from  corresponding  observations  on 
dogs)  estimated  it  as  equal  to  6-J  kilos,  daily,  corresponding  to  y\j.  of  the 
body-weight.     It  contains  : — 

(1.)  Pepsin  (Th.  Schwann,  1836),  the  characteristic  nitrogenous 
hydrolytic  ferment  or  enzym,  which  dissolves  proteids — 3  per  1000. 

(2.)  Hydrochloric  Acid  (Prout,  1824),  0-2-0-3  (according  to  Eichet, 
0-8-2-1)  per  1000;  (in  the  dog,  15  times  more).  This  occurs  free  in  the 
gastric  juice,  as  the  latter  always  contains  more  free  chlorine  than 
bases,  to  which  it  can  be  united  (C.  Schmidt).  Lactic  acid  is  usually 
met  with,  but  it  arises  from  the  fermentation  of  the  carbohydrates  of 
the  food. 

[It  has  been  for  a  long  time  disputed,  whether  the  acidity  of  the  gastric  juice  is 
due  to  hydrochloric  acid  or  to  free  lactic  acid.  The  most  reliable  of  recent  methods 
for  determining  this,  pouit  conclusively  to  hydrochloric  acid  as  the  cause  of  the 
acidity  (Richet  and  others).] 

Tests. — Free  hydrochloric  acid  is  detected  by  the  following  reactions:— 0'025 
p.c.  solution  of  methylviolet  becomes  blue;  or,  alkaline  solution  of  tropajolin 
becomes  lilac;  or,  red  Bordeaux  wine  is  treated  ^vith  amyUc  alcohol  until  its  colour 
almost  disappears— when,  if  dilute  hydrochloric  acid  be  added,  a  rose  colour  is 
obtained. 

(3.)  The  large  amount  of  mucus  which  covers  the  surface  of  the 
mucous  membrane  is  to  be  regarded  as  the  secretion  from  the  goblet 
cells  of  the  mucous  membrane  (p.  321).  [The  reaction  of  the  mucus 
covering  the  walls  of  the  empty  stomach  is  in  many  cases  alkaline 
(M.  Hay).] 

(4.)  Mineral  Salts  (2  per  1000). 

They  are  chiefly  sodium  and  potassium  chlorides,  less  calcic  chloride  (ammonium 
chloride,  also  in  animals),  and  the  compounds  of  phosphoric  acid  with  lime, 
magnesium,  and  iron. 

Amongst  foreign  substances,  which  may  be  introduced  into  the  body,  the  follow- 
ing appear  in  the  gastric  juice,  HI,  after  the  use  of  potassium  iodide— potassium 
sulpho-cyanide,  ferric  lactate,  and  sugar,  and  ammonium  carbonate  in  uraemia. 


326 


SECRETION   OF  GASTRIC   JUICE. 


164.  Secretion  of  Grastric  Juice. 

After  the  discovery  of  the  two  kinds  of  glands  in  the  stomach,  and 
after  it  was  found  that  the  fundus-glands  contained  two  different  forms 
of  cells,  the  question  as  to  whether  the  different  constituents  of  gastric 
juice  were  formed  by  different  histological  elements  came  to  be 
investigated. 

Changes  of  the  Cells  during  Digestion. — During  the  course  of 
digestion,  the  cells  of  the  fundus    (and  pyloric   glands,  dog)  undergo 


Section  of  the  pyloric  mucous  mem- 
brane (Ebstein). 


Fig.  138. 

Pyloric  glands,  showing  changes 
of  the  cells  during  digestion 
(Ebstein). 


important  changes  (Heidenhain,  Ebstein).  During  hunger,  the  chief 
cells  are  dear  and  large,  the  parietal  investing  cells  are  small,  the 
pyloric  cells  clear  and  of  moderate  size.     During  the  first  six  hours  of 


CHANGES    IN   THE   GLANDS   DURING   SECRETION.  327 

digestion,  the  chief  cells  become  enlarged  and  moderately  turbid  or 
granular,  the  parietal  cells  also  enlarge,  while  the  pyloric  cells  remain 
unchanged.  The  chief  cells  become  diminished  and  more  turbid  or 
granular  until  the  9th  hour,  the  parietal  cells  are  still  swollen,  and 
the  pyloric  cells  enlarge.  During  the  last  hours  of  digestion,  the  chief 
cells  again  become  larger  and  clearer,  the  parietal  cells  diminish,  the 
pyloric  cells  decrease  in  size  and  become  turbid  (Figs.  137  and  138). 

[Laiigley  gives  a  clifFerent  description  of  the  appearances  presented  by  these  cells, 
<  luring  different  phases  of  secretory  activity.  The  results  may  be  reconciled  by 
remembering  that  the  gland-cells  were  examined  imder  different  conditions.  The 
secretory  cells  consist  of  a  cell-substance  composed  of  (a)  a  framework  of  living 
protoplasm,  either  m  the  form  of  an  intra-cellular  fibrillar  net-woi-k  (Klein),  or  in 
flattened  bands.  The  meshes  of  this  framework  enclose  at  least  two  chemical 
substances,  viz.,  {b)  a  hyaline  substance  in  contact  with  the  framework,  and 
(c)  spherical  granules  which  are  embedded  in  the  hyaline  substance  (Langley). 
Speaking  generally,  during  active  secretion,  the  granules  decrease  m  number  and 
size,  the  hyaline  substance  increases  in  amount,  the  net-work  grows.  This  is  the 
reverse  of  what  is  stated  above  as  the  observation  of  Heidenhain,  but  the  granular 
appearance  described  by  Heidenhain  after  secretion  is  very  probably  due  to  the 
action  of  the  hardening  agent,  alcohol.  Langley  found  that  in  the  living  con- 
dition, or  after  the  use  of  osmic  acid,  in  some  animals  at  least,  the  chief  cells  are 
granular  during  rest,  but  during  a  state  of  activity  two  zones  are  differentiated, 
an  outer  one,  which  is  clear,  owing  to  the  disappearance  of  the  granules,  and  an  inner 
more  or  less  granular  one.  Granules  reappear  in  the  outer  part  after  rest.  Dur- 
ing digestion,  the  parietal  cells  increase  in  size,  but  do  not  become  granular.  In 
all  cells  containing  much  pepsinogen,  distinct  granules  are  present,  and  the  quan- 
tity of  pepsinogen  varies  directly  with  the  number  and  size  of  the  granules.  In 
the  glands  of  some  animals  there  is  little  difference  between  the  resting  and  active 
phases  (Langley).     Compare  Serous  Olands,  p.  284,  and  Pancreas,  §  168.] 

The  Pepsin  is  formed  in  the  chief  cells  (Heidenhain).  When  these 
are  clear  and  large  they  contain  much  pepsin,  when  they  are  contracted 
and  turbid  the  amount  is  small  (Griitzner).  The  pyloric  glands  are 
also  said  to  secrete  pepsin,  but  only  to  a  small  extent  (Ebstein,  Griitzner, 
Klemensiewicz).  Pepsin  accumulates  during  the  first  stage  of  hunger, 
and  it  is  eliminated  during  digestion  and  also  during  prolonged  hunger. 
According  to  Ebstein,  Griitzner,  and  Langley,  pepsin  as  such,  is  not 
present  within  the  cells,  but  only  a  "mother-substance,"  a  j^sinogen 
substance  {zymogen),  which  occurs  in  the  granules  of  the  chief  cells 
(Langley).  This  zymogen  or  mother-substance  by  itself,  has  no  effect 
upon  proteids;  but  if  it  be  treated  with  hydrochloric  acid  or  sodium 
chloride,  it  is  changed  into  pepsin.  Pepsin  and  pepsinogen  may  be  ex- 
tracted from  the  gastric  mucous  membrane  by  means  of  water  free  from 
acids. 

The  pyloric  glands  secrete  pepsin,  but  no  acid. — Klemensiewicz  excised  in  a  living 
dog  the  pyloric  portion  of  the  stomach,  and  afterwards  stitched  together  the 
duodenum  and  the  remaining  part  of  the  stomach.  The  excised  pyloric  part  with 
its  vessels  intact,  he  stitched  to  the  abdominal  wall,  after  sewing  its  lower  end. 


328  FORMATION    OF   HYDROCHLORIC   ACID. 

The  animals  experimented  on  died,  at  the  latest,  after  six  days.     The  secretion  of 
this  part  was  thin,  alkaline,  and  contained  2  p.c.  of  solids,  including  pepsin. 

In  the  frog,  the  alkaline  glands  of  the  oesophagus  contain  only 
chief  cells  which  produce  pepsin;  while  the  stomach  has  glands  which 
secrete  acid  (and  perhaps  some  pepsin),  and  are  lined  by  parietal 
cells  (Partsch,  v.  Swiecicki).  Amongst  ^s/ics,  the  carps  have  no  fundus- 
glands  in  the  stomach  (Luchau). 

[The  secreting  portions  of  glands  of  the  cardiac  sac  (crop)  of  the  herring,  are 
lined  by  a  single  layer  of  polygonal  cells  (W.  Stirling),] 

The  hydrochloric  acid  is  formed,  according  to  Heidenhain,  by  the 
parietal  cells.  It  occurs  on  the  free  surface  of  the  gastric  mucous  mem- 
brane as  well  as  in  the  ducts  of  the  gastric  glands.  The  deep  parts  of 
the  glands  are  usually  alkaline.  Free  HCl  is  detected  in  human  gastric 
juice,  within  45  minutes  to  1-2  hours  after  a  moderate  meal  (von  den 
Velden,  and  others),  and  3-4  hours  after  a  full  meal  (Edinger);  the 
amount  gradually  increases  during  the  process  of  digestion  (Kretschy 
and  Uffelmann). 

CI.  Bernard  injected  potassium  ferrocyanide  and  afterwards  lactate  of  iron  into 
the  veins  of  a  dog.  After  death,  blue  colouration  occurred  only  in  the  upper,  acid 
layers  of  the  mucous  membrane.  Nevertheless  we  must  assume,  that  the  hydrochloric 
acid  is  secreted  in  the  parietal  cells  of  the  fundus  of  the  glands,  and  that  it  is 
rapidly  carried  to  the  surface  along  with  the  pepsin. 

Briicke  neutralised  the  surface  of  the  gastric  mucous  membrane  with  magnesia 
usta,  chopped  up  the  mucous  membrane  with  water  and  left  it  for  some  time,  when 
the  fluid  had  again  an  acid  reaction. 

With  regard  to  the  formation  of  a  free  acid,  the  following  statements 
may  be  noted : — The  parietal  cells  form  the  hydrochloric  acid  from  the 
chlorides  which  the  mucous  membrane  takes  up  from  the  blood.  Accord- 
ing to  Voit,  the  formation  of  acid  ceases  if  chlorides  be  withheld  from  the 
food.  The  active  agent  is  lactic  acid,  which  splits  up  sodium  chloride 
and  forms  free  HCl  (Maly).  The  base  set  free  is  excreted  by  the  urine, 
rendering  it  at  the  same  time  less  acid  (Jones,  Maly).  The  formation 
of  acid  is  arrested  during  hunger.  According  to  H.  Schulz,  watery 
solutions  of  alkaline  and  earthy  chlorides  are  decomposed,  even  at  a  low 
temperature,  by  COj,  free  hydrochloric  acid  being  formed. 

[A  solution  of  sulphate  of  soda,  not  sufficiently  strong  to  cause  inflammatory 
redness  of  the  gastric  mucous  membrane,  yet  concentrated  enough  to  excite 
secretion,  causes,  when  injected  into  the  empty  stomach,  the  pouring  out  of  an 
alkaline,  not  an  acid  secretion  (Matthew  Hay).] 

Secretion. — When  the  stomach  is  empty,  there  is  no  secretion  of 
gastric  juice ;  this  occurs  only  after  appropriate  (mechanical,  thermal, 
or  chemical)  stimulation.  In  the  normal  condition,  it  takes  place  imme- 
diately on  the  introduction  of  food,  but  also  of  indigestible  substances, 


INFLUENCE  OF  NERVES   ON   THE  SECRETION.  329 

such  as  stones.  The  mucous  membrane  becomes  red,  and  the  circulation 
more  active,  so  that  the  venous  blood  becomes  brighter.  [That  the 
vagi  are  concerned  in  this  vascular  dilatation,  is  proved  by  the  fact, 
that  if  both  nerves  be  divided  during  digestion,  the  gastric  mucous 
membrane  becomes  pale  (Rutherford).]  The  secretion  is  probably 
caused  reflexly,  and  the  centre  is  perhaps  in  the  wall  of  the 
stomach  itself,  (Meissner's  plexus  in  the  sub-mucous  coat).  It  is 
asserted  that  the  idea  of  food,  especially  during  hunger,  excites 
secretion.  As  yet  we  do  not  know  the  effect  produced  upon  the 
secretion  by  stimulation  or  destruction  of  other  nerves — e.g.,  vagus, 
sympathetic.  [There  is  no  nerve  passing  to  the  stomach,  whose 
stimulation  causes  a  secretion  of  gastric  juice,  as  the  chorda  tympani 
does  in  the  submaxillary  gland.  If  the  vagi  be  divided  sufficiently 
low  down  not  to  interfere  with  respiration,  the  introduction  of  food 
still  causes  a  secretion  of  gastric  juice;  even  if  the  sympathetic  branches 
be  divided  at  the  same  time,  secretion  still  goes  on  (Heidenhain).  This 
experiment  points  to  the  existence  of  local  secretory  centres  in  the 
stomach.  But  there  is  evidence  to  show  that  there  is  some  connection, 
perhaps  indirect,  between  the  central  nervous  system  and  the  gastric 
glands.  Richet  observed  a  case  of  complete  occlusion  of  the  oesophagus 
in  man,  produced  by  swallowing  a  caustic  alkali.  A  gastric  fistula  was 
made,  through  which  the  person  could  be  nourished.  On  placing  sugar 
or  lemon-juice  in  the  person's  mouth,  Richet  observed  secretion  of 
gastric  juice.  In  this  case,  no  saliva  could  be  swallowed  to  excite 
secretion,  so  that  it  must  have  taken  place  through  some  nervous 
channels.  Even  the  sight  or  smell  of  food  caused  secretion.  Emo- 
tional states  also  are  known  to  interfere  with  gastric  digestion.] 

Heidenhain  isolated  a  part  of  the  mucous  membrane  of  the  fundus 
so  as  to  form  a  blind-sac  of  it,  and  he  found  that  mechanical  stimula- 
tion caused  merely  local  secretion.  If,  however,  at  the  same  time, 
absorption  of  digested  matter  also  occurred,  secretion  took  place  over 
larger  surfaces. 

The  statement  of  SchiflF,  that  active  gastric  juice  is  secreted  only  after  absorption 
of  the  so-called  peptogenic  substances  (especially  dextrin),  is  denied. 

Action  of  Alcohol.— Small  doses  of  alcohol,  introduced  into  the  stomach, 
increase  the  secretion  of  gastric  juice;  large  doses  arrest  it.  Artificial  digestion 
is  not  affected  by  10  p.c.  of  alcohol,  is  retarded  by  20  p.c.,  and  is  arrested 
by  stronger  doses.  Beer  and  wine  hinder  digestion,  and  in  an  undiluted  form 
they  interfere  with  artificial  digestion  (Buchner). 

The  gastric  juice,  which  passes  into  the  duodenum  after  gastric 
digestion  is  completed,  is  neutralised  by  the  alkali  of  the  intestinal 
mucous  membrane  and  the  pancreatic  juice.  Part  of  the  pepsin  is 
re-absorbed  as  such,  and  is  found  in  traces  in  the  urine  and  muscle- 
juice  (Briicke). 


330  METHODS    OF    OBTAINING   GASTRIC   JUICE. 

If  the  gastric  juice  be  completely  discharged  externally  through  a  gastric 
fistula,  the  alkalinity  of  the  intestine  is  so  strong,  that  the  urine  becomes  alkaline 
(Maly). 

The  acid  gastric  juice  of  the  new-horn  child  is  already  fairly  active;  casein  is 
most  easily  digested  by  it,  then  fibrin  and  the  other  proteids  (Zweifel).  When 
the  amount  of  acid  is  too  great  in  the  stomach  of  sucklings,  large  firm  indigestible 
masses  of  casein  are  apt  to  be  formed  (Simon,  Biedert — see  MilJc).  This  occurs 
more  especially  after  the  use  of  cow's  milk. 

165.   Methods  of  obtaining  Gastric  Juice. 

Historical. — Spallanzani  caused  starving  animals  to  swallow  small  pieces  of 
sponge,  enclosed  in  perforated  lead  capsules,  and  after  a  time,  when  the  sponges 
had  become  saturated  with  gastric  juice,  he  removed  them  from  the  stomach.  To 
avoid  the  admixture  with  saliva,  the  sponges  are  best  introduced  through  an 
opening  in  the  cesophagus  (Manassein).  Starving  animals  were  forced  to  swallow 
small  stones,  which  excited  the  secretion  of  gastric  juice.  After  a  time,  the 
animals  were  killed,  and  the  juice  collected. 

Dr.  Beaumont  (1825),  an  American  physician,  was  the  first  to  obtain  human 
gastric  juice,  from  a  Canadian  named  Alexis  St.  Martin,  who  was  injured  by  a 
gunshot  wound,  whereby  a  permanent  gastric  fistula  was  established.  Various 
substances  were  introduced  through  the  external  opening,  which  was  partially 
covered  with  a  fold  of  skin,  and  the  time  required  for  their  solution  was  noted. 
Bassow  (1842,)  Blondlot  (1843),  and  Bardeleben  (1849)  were  thereby  led  to  make 
artificial  gastric  fistulee. 

Gastric  Fistula. — The  anterior  abdominal  wall  is  opened  by  a  medium  incision 
just  below  the  ensiform  cartilage,  the  stomach  is  exposed,  and  its  anterior  wall 
opened  and  afterwards  stitched  to  the  margins  of  the  abdominal  walls.  A  strong 
cannula  is  placed  in  the  fistula  thus  formed.  A  silver  cannula  about  an  inch  wide, 
and  with  a  flange,  is  introduced  into  the  stomach,  so  that  the  flange  lies  in  contact 
with  the  gastric  mucous  membrane.  The  inner  surface  of  the  tube  of  the  cannula 
is  provided  with  a  screw  into  which  a  similar  cannula  is  screwed,  and  its  flange 
comes  in  contact  with  the  abdominal  wall.  When  the  two  are  placed  together 
they  have  the  form  of  J^,  where  a  passes  into  b.  [When  the  two  parts  of  the 
cannula  are  screwed  together,  the  flanges  keep  the  abdominal  walls  and  gastric 
walls  in  contact,  until  they  become  united  organically.]  As  a  rule,  the  tube  is 
kept  corked.  If  the  ducts  of  the  salivary  glands  be  tied,  a  perfectly  uncompli- 
cated object  for  investigation  is  obtained. 

According  to  Leube,  dilute  human  gastric  juice  may  be  obtained  by  means  of  a 
syphon-like  tube  introduced  into  the  stomach.  Water  is  introduced  first,  and 
after  a  time  it  is  withdrawn. 

Artificial  Gastric  Juice. — An  important  advance  was  made  when  Eberle 
(1834)  prepared  "artificial  gastric  juice,"  by  extracting  the  pepsin  from  the  gastric 
mucous  membrane  with  dilute  hydrochloric  acid.  A  certain  degree  of  concentra- 
tion, however,  is  required  (Schwann).  Four  litres  of  a  watery  solution  of 
0"8-l'0-l*7  of  pure  hydrochloric  acid  per  1000  (Brltcke)  are  sufiicient  to  extract 
the  chopped-up  mucous  membrane  of  the  pig's  stomach.  Half  a  litre  is  infused 
with  the  stomach  and  renewed  every  six  hours.  The  collected  fluid  is  afterwards' 
filtered  (Hoppe-Seyler.)  The  substance  to  be  digested  is  placed  in  this  fluid,  and 
the  whole  is  kept  at  the  temperature  of  the  body,  but  it  is  necessary  to  add  a  little 
HCl  from  time  to  time  (Schwann).  The  HCl  may  be  replaced  by  ten  times  its 
volume  of  lactic  acid  (Lehmann)  and  also  by  nitric  acid;  while  oxalic,  sulphuric, 
phosphoric,  acetic,  formic,  succinic,  tartaric,  and  citric  acid  are  much  less  active ; 
butyric  and  salicylic  acids  are  inactive. 


ACTION   ON    PROTEIDS.  331 

Von  Wittioh's  Glycerine  Method.— («)  Glycerine  extracts  pepsin  in  a  very 
pure  form.  The  mucous  membrane  is  rubbed  up  with  glass  until  it  forms  a  pulp, 
mixed  with  glycerine,  and  allowed  to  stand  for  eight  days.  The  fluid  is  pressed 
through  cloth,  and  the  filtrate  mixed  with  alcohol,  thus  precipitating  the  pepsin, 
which  is  washed  with  alcohol  and  afterwards  dissolved  in  the  dilute  HCl,  to  form 
an  artificial  digestive  fluid.  [The  addition  of  a  few  drops  of  the  glycerine  extract 
to  dilute  HCl,  is  sufficient  for  experiments  on  artificial  digestion.] 

(b.)  Or  the  mucous  membrane  may  be  placed  for  24  hours  in  alcohol,  and  after- 
wards dried  and  extracted  for  S  days  with  glycerine. 

(c.)  Wm.  Roberts  has  used  other  agents  for  extracting  enzyms  (p.  295). 

Preparation  of  pure  pspsiu. — Briicke  pours  on  the  pounded  mucous  membrane 
of  the  pig's  stomach  a  5  per  cent,  solution  of  phosphoric  acid,  and  afterwards 
adds  lime  water  until  the  acid  reaction  is  scarcely  distinguishable.  A  copious 
precipitate,  which  carries  the  pepsin  with  it,  is  produced.  This  precipitate  is 
collected  on  cloth,  repeatedly  washed  with  water,  and  afterwards  dissolved  in  very 
dilute  HCl.  A  copious  precipitation  is  caused  in  this  fluid,  by  gradually  adding  to 
it  a  mixture  of  cholesterin  in  four  parts  of  alcohol  and  one  of  ether.  The 
cholesterin-pulp  is  collected  on  a  filter,  washed  with  water  containing  acetic  acid, 
and  afterwards  wath  pure  water.  The  cholesterin-pulp  is  placed  in  ether  to  dis- 
solve the  cholesterin,  and  the  ether  is  then  removed.  The  small  watery  deposit 
contains  the  pepsin  in  solution. 

Properties. — Pepsin  so  prepared  is  a  colloid  substance ;  it  does  not 
react  like  albumin  with  the  following  tests,  viz. : — it  does  not  gi^^e  the 
xanthoprotein  reaction  (p.  333),  is  not  precipitated  by  acetic  acid  and 
potassium  ferrocyanide,  nor  by  tannic  acid,  mercuric  chloride,  silver 
nitrate,  or  iodine.  In  other  respects  it  belongs  to  the  group  of 
albumins.  It  is  rendered  inactive  in  an  acid  fluid  by  heating  it  to 
o.5°-60°C.  (Ad.  Mayer). 

166.  Process  of  Grastric  Digestion. 

Chyme.— ^The  finely  divided  mixture  of  food  and  gastric  juice  is 
called  chyme.  The  gastric  juice  acts  upon  certain  constituents  of  this 
chyme. 

L— Action  on  Proteids. 

Pepsin  and  the  dilute  hydrochloric  acid,  at  the  temperature  of  the  body, 
transform  proteids  into  a  soluble  form,  to  Avhich  Lehmann  (1850)  gave 
the  name  of  "  Peptone."  During  this  change,  they  are  first  transformed 
into  a  substance  which  has  the  characters  of  syntonin  (Mulder). 
Syntonin  is  an  acid-albumin  or  albuminate;  when  neutralised  by  an 
alkali  [e.g.,  sodium  carbonate],  the  albuminate  is  again  precipitated. 
An  intermediate  product  is  formed,  a  body  which,  as  it  were,  stands 
midway  between  albumin  and  peptone.  This  is  called  x>ropeptone 
(Schmidt-Miilheim),  and  is  identical  with  Kiihne's  hemialbuminose  and 
Meissner's  parapeptone.    It  is  not  coagulated  by  heat,  but  is  precipitated 


332  ACTION   ON    PROTEIDS. 

by  concentrated  solution  of  common  salt.  It  is  soluble  in  water  in  the 
presence  of  weak  acids  and  alkalies.  It  is  precipitated  by  nitric  acid 
and  adheres  firmly  to  the  walls  of  the  reagent  glass;  it  dissolves  in 
nitric  acid  with  the  aid  of  heat,  giving  an  intense  yellow  colour,  and  is 
again  precipitated  in  the  cold  (E.  Salkowski).  The  compound  of 
nitric  acid  with  propeptone  is  of  the  nature  of  a  salt,  and  it  is 
deposited  in  the  form  of  sphaeroids. 

By  the  continued  action  of  the  gastric  juice,  the  propeptone  passes 
into  a  true  soluble  peptone.  The  unchanged  albumin  behaves  like  an 
anhydride  with  respect  to  the  peptone.  The  formation  of  peptone  is 
due  to  the  taking  up  of  a  molecule  of  water,  under  the  influence  of  the 
hydrolytic  ferment  pepsin,  and  the  action  takes  place  most  readily  at  the 
temperature  of  the  body.  Gelatin  is  changed  into  a  gelatin-peptone. 
The  greater  the  amount  of  pepsin  (within  certain  limits),  the  more 
rapidly  does  the  solution  take  place.  The  pepsin  suffers  scarcely  any 
change,  and  if  care  be  taken  to  renew  the  hydrochloric  acid  so  as  to 
keep  it  at  a  uniform  amount,  the  pepsin  can  dissolve  new  quantities  of 
albumin.  Still,  it  seems  that  some  pepsin  is  used  up  in  the  process  of 
digestion  (Griitzner).  Proteids  are  introduced  into  the  stomach  either 
in  a  solid  (coagulated)  or  fluid  condition.  Casein  alone  of  the  fluid 
forms  is  precipitated  or  coagulated,  and  afterwards  dissolved.  The 
non-coagulated  proteids  are  transformed  into  syntonin,  without  being 
previously  coagulated,  and  are  then  changed  into  propeptone  and 
directly  peptonised,  i.e.,  actually  dissolved. 

When  albumin  is  digested  by  pepsin  at  the  temperature  of  the  body, 
a  not  inconsiderable  amount  of  heat  disappears,  as  can  be  proved  by 
calorimetric  experiment  (Maly).  Hence,  the  temperature  of  the  chyme 
in  the  stomach  falls  0'2°-0*6°C  in  2-3  hours  (v.  Vintschgau  and 
Dietl). 

Coagulated  albumin  may  be  regarded  as  the  anhydride  of  the  fluid 
form,  and  the  latter  again  as  the  anhydride  of  peptone.  The  peptones, 
therefore,  represent  the  highest  degree  of  hydration  of  the  proteids. 

Hence,  peptones  may  be  formed  from  proteids  by  those  reagents  which  usually 
cause  hydration,  viz.,  treatment  with  strong  acids,  (from  tibrin,  with  0'2  HCl — 
V.  Wittich),  caustic  alkalies,  putrefactive,  and  various  other  ferments  and  ozone 
(Gorup-Besanez). 

The  anhydride  proteid  has  been  prepared  from  the  hydrated  form. 
Henniger  and  Hofmeister,  by  boiling  pure  peptone  with  dehydrating 
substances  (anhydrous  acetic  acid  at  80°C.),  have  succeeded  in  decom- 
posing it  into  a  body  resembling  syntonin. 

Properties  of  Peptones: — (1)  They  are  completely  soluble  in  water. 
(2)  They  difiiise  very  easily  through  membranes  (Funke),  and  are 
twelve  times  as  diffusible  as  fluid  albumin ;  the  fibrin-peptone  is  said 


PROPERTIES   OF   PEPTONES.  333 

to  crystallise  (Drechsel).  (3)  They  filter  quite  easily  through  the 
pores  of  animal  membranes  (Acker).  (-4)  They  are  not  precipitated  by 
boiling  nitric  acid,  acetic  acid  and  potassium  ferrocyanide,  weak  alcohol, 
or  metaphosphoric  acid.  (5)  They  are  j^recipitated  from  neutral  or 
feebly  acid  solutions  by  mercuric  chloride,  mercuric  nitrate  [Millon's 
reagent],  silver  nitrate,  basic  lead  acetate,  potassio-mercuric  iodide, 
tannic  acid,  picric  acid,  bile  acids,  strong  alcohol,  phosphoro-wolframic 
acid,  and  phosphoro-molybdic  acid  (Briicke).  (6)  With  Millon's 
reagent  they  react  like  proteids,  and  give  a  red  colour,  and  with  nitric 
acid  give  the  yellow  xantho-protein  reaction.  (7)  "With  caustic  potash 
or  soda  and  a  small  quantity  of  cupric  sulphate,  they  give  a  beautiful 
purplish-red  colour  (Biuret-reaction).  (8)  They  rotate  the  plane  of 
polarised  light  to  the  left. 

The  biuret-reaction  is  obtained  with  propeptone,  as  well  as  with  a  form  of 
albumin,  which  is  formed  during  artificial  digestion  and  is  soluble  in  alcohol.  It 
is  called  Alkophyr  by  Briicke. 

[Darby's  fluid  meat  gives  all  the  above  reactions,  and  is  very  useful 
for  studying  the  tests  for  peptones.] 

Freparation. — Pure  peptones  are  prepared  by  taking  fluid  which  contains 
them  and  neutralising  it  with  barium  carbonate,  evaporating  upon  a  water-bath, 
and  filtering.  The  barium  is  removed  from  the  filtrate  by  the  careful  addition  of 
sulphuric  acid,  and  subsequent  filtration  (Hoppe-Seyler).  Brieger  extracted  from 
gastric  peptones  by  amylic  alcohol  a  peptone-free  poison,  with  actions  like  those  of 
eurara.  It  belongs  to  the  group  of  ptomaines— i.e.,  alkaloids  obtained  from  dead 
bodies. 

Peptones  are  undoubtedly  those  modifications  of  albumin  or  proteids 
which,  after  their  absorption  from  the  intestinal  canal  into  the  blood, 
are  destined  to  be  used  to  make  good  the  proteids  used  up  in  the 
human  organism.  By  giving  peptones  (instead  of  albumin)  as  food, 
life  can  not  only  be  maintained,  but  there  may  even  be  an  increase  of 
the  body-weight  (Pl6sz  and  Maly,  Adamkiewicz). 

The  N-equilibrium  in  the  metabolism  of  the  body  may  be  kept  up 
by  administering  I'll  grammes  of  peptones,  artificially  prepared  from 
flesh,  per  kilo,  of  the  body -weight  (Catillon).  After  being  absorbed 
into  the  blood-stream,  peptones  are  retransformed,  first  into  propeptone, 
and  then  into  serum-albumin. 

Conditions  Affecting  Gastric  Digestion. — The  presence  of  already-formed 
peptones  interferes  with  the  action  of  the  gastric  juice,  in  so  far  as  the  greater 
concentration  of  the  fluid  interferes  with  and  limits  the  mobility  of  the  fluid  par- 
ticles (Hoppe-Seyler).  Boiling  concentrated  acids,  alum,  and  tannic  acid,  alkalinity 
of  the  gastric  juice  (,e.g.,  by  the  admixture  of  much  saliva)  abolish  the  action. 
The  salts  of  the  heavy  metals,  which  cause  precipitates  with  pepsin,  peptone, 
and  mucin,  interfere  with  gastric  digestion,  and  so  do  concentrated  solutions  of 
alkaline  salts,  common  salt,  magnesium  and  sodium  sulphates.  Alcohol  precipi- 
tates the  pepsin,  but  by  the  subsequent  addition  of  water  it  is  redissolved,  so  that 


334 


ARTIFICIAL  DIGESTION   OF   PROTEIDS. 


digestion  goes  on  as  before.  Any  means  that  prevent  the  proteid  bodies  from 
swelling  up,  as  by  binding  them  firmly,  impede  digestion.  Slightly  over  half  a 
pint  of  cold  water  does  not  seem  to  disturb  healthy  digestion,  but  it  does  so  in 
cases  of  disease  of  the  stomach.  Copious  draughts  of  water  and  violent  muscular 
exercise,  disturb  digestion;  while  warm  clothing,  especially  over  the  pit  of 
the  stomach,  aids  it.     Menstruation  retards  gastric  digestion. 

[The  action  of  gastric  juice  on  proteids  may  be  observed  outside  the 
body,  and  we  can  prove,  as  is  shown  in  the  following  table,  after 
Eutherford,  that  pepsin  and  an  acid — e.g.,  hydrochloric,  along  with 
water — are  essential  to  the  formation  of  gastric  peptones : — 


Beaker  A. 

Beaker  B. 

Beaker  C. 

Water. 

Pepsia,  0-3  per  cent. 

Fibrin. 

Water. 

HCl,  0-2  per  cent. 

Fibrin. 

Water. 

Pepsin,  0"3  per  cent. 

HCl,      0-2       „ 

Fibrin. 

Keep  all  in  water-bath 
at  38°C. 

Unchanged. 

Fibria  swells  up,  be- 
comes clear,  and  is 
changed   into    acid- 
albumin  or  syntonin. 

Fibrin  ultimately 
changed       into 
peptone. 

The  fibrin  is  obtained  by  beating  blood,  and  afterwards  washing  and 
boiling  it  to  destroy  any  traces  of  pepsin.  The  fibrin  may  be  coloured 
with  carmine,  and  from  the  rapidity  with  which  the  fibrin  is  dissolved 
— i.e.,  the  depth  of  the  colour  of  the  fluid — we  may  estimate  the 
digestive  power  of  the  gastric  juice.  Similar  experiments  may  be 
made  with  unboiled  white  of  egg,  mixed  with  nine  volumes  of  water, 
and  filtered  through  muslin.] 

[In  all  animals  gastric  digestion  is  essentially  an  add  digestion,  and 
between  the  native  proteid,  fibrin,  albumin,  or  any  other  form  of 
proteid,  and  the  end-product  peptone,  there  are  many  intermediate 
substances  and  bye-products,  whose  properties  and  characters  have  still 
to  be  investigated.  If  the  peptones  be  decomposed,  small  quantities  of 
leucin  and  tyrosin  are  produced.  W.  Roberts  obtained  a  bitter 
substance  during  gastric  digestion.] 


11.  Action  on  other  Constituents  of  Food. 

Milk  coagulates  when  it  enters  the  stomach,  owing  to  the  precipitation 
of  the  casein,  and  in  doing  so,  it  entangles  some  of  the  milk  globules. 
During  the   process  of  coagulation,  heat   is   given   off"  (Mosso,  Ad. 


ACTION   ON   OTHER   CONSTITUENTS   OF   FOODS.  335 

Mayer).  The  free  hydrochloric  acid  of  the  gastric  juice  is  itself 
sufficient  to  precipitate  it ;  the  acid  removes  from  the  alkali-albuminate 
or  casein  the  alkali  which  keeps  it  in  solution.  Hammarsten  separated 
a  special  ferment  from  the  gastric  juice — quite  distinct  from  pepsin — the 
milk-curdling  ferment  whfch,  quite  independently  of  the  acid,  pre- 
cipitates the  casein  either  in  neutral  or  alkaline  solutions.  It  is  this 
ferment  or  rennet  which  is  used  to  coagulate  casein  in  the  making  of 
cheese.  [Rennet  is  an  infusion  of  the  fourth  stomach  of  the  calf  in 
brine.] 

One  part  of  the  rennet -ferment  can  precipitate  800,000  parta  of  casein.  When 
casein  coagulates,  two  new  proteids  seem  to  be  formed — the  coagulated  proteid 
which  constitutes  cheese,  and  a  body  resembling  peptone  dissolved  in  the  whey. 
The  addition  of  calcium  chloride  accelerated,  while  water  retarded  the  coagu- 
lation (Hammarsten). — See  Milk. 

Casein  is  first  precipitated  in  the  stomach,  then  a  body  like  syntonin  is  formed, 
and  finally  peptone.  During  the  process,  a  substance  containing  phosphorus 
and  resembling  nuclein  appears  (Lubavin). 

There  is  a  "  lactic  acid,  ferment "  (Hammarsten)  also  present,  which 
changes  milk-sugar  into  lactic  acid.  Part  of  the  milk-sugar  is  changed 
in  the  stomach  and  intestine  into  grape-sugar. 

Action  on  Carbohydrates. — Gastric  juice  does  not  act  as  a  solvent  of 
starch,  inulin,  or  gimis.  Cane-sugar  is  slowly  changed  into  grape-sugar 
(Bouchardat  and  Sandras,  1845,  Lehmann).  According  to  UflFelmaun, 
the  gastric  mucus,  and  according  to  Leube,  the  gastric  acids  are  the  chief 
agents  in  this  process.  [Matthew  Hay  has  failed  to  find  any  organic 
ferment  in  the  stomach  capable  of  digesting  sugar.]  Diu'ing  the 
digestion  of  true  cartilage,  there  is  formed  a  chondrin-peptone,  and  a 
body  which  gives  the  sugar  reaction  with  Trommer's  test.  Perfectly 
pure  elastin  yields  an  elastin-peptone,  similar  to  albumin-peptone,  and 
hemi-elastin  similar  to  hemi-albuminose  (Horbaczewski). 

Fats  formerly  were  stated  not  to  be  acted  on,  but  the  recent  re- 
searches of  Cash  and  Ogata  show  that  a  small  part  of  the  fats  is  broken 
up  into  glycerine  and  fatty  acids. 

[We  still  require  further  observations  on  the  gastric  digestion  of  fats.  Kichet 
observed  in  his  case  of  fistula  (p.  329),  that  fatty  matters  remained  a  long  time  ui 
the  stomach,  and  Ludwig  found  the  same  result  in  the  dog.  In  some  dyspeptics, 
rancid  eructations  often  take  place  towards  the  end  of  gastric  digestion.  W. 
Roberts  suggests  that  there  may  be  some  slight  decomposition  of  neutral  fats  and 
liberation  of  fatty  acids.  In  this  connection,  it  is  important  to  remember  that 
fatty  acids  are  liberated  from  neutral  fats  by  bacteroid  ferments  (zymophytes).] 

III.  Action  of  Grastric  Juice  on  the 
various  Tissues, 

(1.)  The  gelatin-yielding  substance  (collagen)  of  all  the  connective-tissues  (con- 
nective-tissue, white  fibro-cartilage,   and  the  matrix  of  bone),  as  well  as  glutin, 


336  ACTION   ON  VARIOUS  TISSUES, 

are  dissolved  and  peptonised  by  the  gastric  juice  (Uffelmann).  (2.)  The  structute' 
less  membranes  (membranse  propria)  of  glands,  sarcolemma,  Schwann's  sheath  of 
nerve-fibres,  capsule  of  the  lens,  the  elastic  laminse  of  the  cornea,  the  membranes 
of  fat  cells  are  dissolved,  but  the  true  elastic  (fenestrated)  membranes  and  fibres 
are  not  affected.  (3.)  The  striped-muscular  substance,  after  solution  of  the 
sarcolemma,  breaks  up  transversely  into  discs,  and,  like  non-striped  muscle,  is 
dissolved  and  forms  a  true  soluble  peptone,  but  parts  of  the  muscle  alvrays  pass 
into  the  intestine.  (4. )  The  albuminous  constituents  of  the  soft  cellular  elements 
of  glands,  stratified  epithelium,  endothelium,  lymph-cells,  form  peptones,  but  the 
nuclein  of  the  nuclei  does  not  seem  to  be  dissolved.  (5.)  The  horny  parts  of  the 
epidermis,  nails,  hair,  as  well  as  chitin,  silk,  conchiolin,  and  spongin  of  the 
lower  animals  are  indigestible,  and  so  are  amyloid-substance  and  wax.  (6.)  The 
red  hlood-corpuscles  are  dissolved,  the  haemoglobin  decomposed  into  haematin  and 
a  globulin-like  substance;  the  latter  is  peptonised,  while  the  former  remains  un- 
changed, and  is  partly  absorbed  and  transformed  into  bile-pigment.  Fibrin  ia 
easily  dissolved  to  form  propeptone  and  fibrin-peptone.  (7.)  Mucin,  which  is  also 
secreted  by  the  goblet  cells  of  the  stomach,  passes  through  the  intestines  un- 
changed. (8.)  Vegetable  fats  are  not  affected  by  the  gastric  juice;  these  cells 
yield  their  protoplasmic  contents  to  form  peptones,  while  the  cellulose  of  the  cell- 
wall,  in  the  case 'of  man  at  least,  remains  undigested.  During  putrefaction  in  the 
intestine,  some  cellulose  seems  to  be  transformed  into  sugar. 

Why  the  Stomach  does  not  digest  itself.— That  the  stomach  can  digest 

living  things  is  shown  by  the  following  facts:— The  limb  of  a  living  frog  was  intro- 
duced through  a  gastric  fistula  into  the  stomach  of  a  dog  (CI.  Bernard)— the  ear  of  a 
rabbit  (Pavy)  was  also  introduced — and  both  were  partly  digested.  The  margins  of 
agastric  ulcer  and  of  gastric  fistulsB  in  man  are  attacked  by  the  gastric  juice.  John 
Hunter  (1772)  discussed  the  question  as  to  why  the  stomach  does  not  digest  itself. 
Not  unfrequently  after  death  the  posterior  wall  of  the  stomach  is  found  digested, 
[more  especially  if  the  person  die  after  a  full  meal  and  the  body  be  kept  in  a  warm 
place,  whereby  the  contents  of  the  stomach  may  escape  into  the  peritoneum. 
CI.  Bernard  showed,  that  if  a  rabbit  be  killed  and  placed  in  an  oven  at  the 
temperature  of  the  body,  the  walls  of  the  stomach  are  attacked  by  its  own 
gastric  juice.  Fishes  also  are  frequently  found  with  their  stomach  partially 
digested  after  death].  It  would  seem,  therefore,  that  so  long  as  the  circulation 
continues,  the  tissues  are  protected  from  the  action  of  the  acid  by  the  alkaline 
blood;  this  action  cannot  take  place  if  the  reaction  be  alkaline  (Pavy).  Ligature 
of  the  arteries  to  the  stomach,  according  to  Pavy,  causes  digestive  softening  of  the 
gastric  mucous  membrane.  The  thick  layer  of  mucus  may  also  aid  in  protecting 
the  stomach  from  the  action  of  its  own  gastric  juice  (CI.  Bernard). 

167.  Gases  in  the  Stomaoli. 

The  stomach  always  contains  a  certain  quantity  of  gases,  which  are 
derived  partly  from  the  gases  swallowed  with  the  saliva,  partly 
from  gases  which  pass  backwards  from  the  duodenum,  and  partly  from 
air  swallowed  directly. 

If  the  larynx  and  hyoid  bone  (p.  311)  are  suddenly  and  forcibly  raised  upwards 
and  forwards,  there  passes  into  the  space  behind  the  larynx  a  considerable  amount 
of  air,  which,  on  the  latter  regaining  its  position,  is  swallowed,  owing  to  the 
peristalsis  of  the  cesophagus.  We  can  feel  the  passage  of  such  a  mass  of  air  as  it 
passes  along  the  cesophagus.  In  this  way  a  considerable  volume  of  air  may  be 
swallowed. 


STRUCTURE   OF  THE  PANCREAS. 


337 


The  air  in  the  stomach  is  constantly  undergoing  changes,  whereby 
its  0  is  absorbed  by  the  blood,  and  for  1  vol.  of  0  absorbed  2  vols,  of 
COo  are  returned  to  the  stomach  from  the  blood.  Hence,  the  amount 
of  0  in  the  stomach  is  very  small,  the  CO.^  very  considerable  (Planer). 

Gases  in  the  Stomach — Vol.  per  cent.  (Planer). 


Human  Subject  after  Vegetable  Diet. 

Dog. 

I. 

11. 

I 

After  Animal  Diet. 

IE. 
After  Legumes. 

CO2,    .     .      20-79 
H,    .     .       6-71 
N,     .     .     72-50 

0, 

33-83 

27-58 

38-22 

0-37 

25-2 

68-7 
6-1 

32-9 

66-3 
0-8 

A  part  of  the  CO2  is  set  free  by  the  acid  of  the  stomach  from  the 
saliva,  which  contains  much  CO2  (p.  292).  The  N  acts  as  an  in- 
different substance. 

Abnormal  development  of  gases  in  persons  suffering  from  gastric  catarrh, 
only  occurs  when  the  gastric  contents  are  neutral  in  reaction  ;  during  the  butyric 
acid  fermentation  H  and  CO2  are  formed,  whUe  the  acetic-acid  and  lactic -acid 
fermentations  do  not  cause  the  formation  of  gases.  Marsh  gas  (CH4)  has  also 
been  found,  but  it  must  come  from  the  intestine,  as  it  can  only  be  formed  when  no 
O  is  present  [Intestinal  Gases). 

168.  Structure  of  the  Pancreas. 

The  pancreas  is  built  on  the  type  of  compound  tubular  or  acino- 
tubular  glands,  and  in  its  general  arrangement  into  lobes,  lobules  and 
system  of  ducts  and  acini,  it  corresponds  exactly 
to  the  true  salivary  glands.  The  epithelium 
lining  the  ducts  is  not  at  all,  or  only  faintly, 
striated.  The  acini  are  tubular  or  flask- 
shaped,  and  often  convoluted.  They  consist  of 
a  membrana  propria,  resembling  that  of  the 
salivary-glands,  lined  by  a  single  layer  of  some- 
what cylindrical  cells,  with  a  more  or  less 
conical  apex  towards  the  very  narrow  lumen  of 
the  acini.  [As  in  the  salivary  glands,  there 
is  a  narrow  intermediary  part  of  the  ducts 
opening  into  the  acini,  and  lined  by  flattened 
epithelium].  The  cells  lining  the  acini  consist 
of  two  zones  (Fig.  139)  : — 

(1.)  The  smaller  parietal  layer  (outer)  is  transparent,  homogeneous, 
sometimes  faintly  striated,  and  readily  stained  with  carmine  and  log- 

22 


Fig  1.39 
Section  of  the  tubes  of 
the   pancreas  in   the 
fresh  condition. 


338 


STRUCTURE   OF  THE   PANCREAS. 


wood ;  and  (2.)  the  inner  layer  (Bernard's  granular  layer)  is  strongly 
granular,  and  stains  but  slightly  with  carmine.  It  undoubtedly  con- 
tributes to  the  secretion  by  giving  off  material,  the  granules  being 
dissolved,  and  this  zone  becoming  smaller  (Heidenhain).     The  spherical 


Fig.  140. 

Changes  of  the  pancreatic  cells  in  various  stages  of  activity — 1,  During  hunger  ;  2, 
in  the  first  stage  of  digestion ;  3,  in  the  second  stage ;  4,  during  paralytic 
secretion. 

nucleus  lies  between  the  two  zones.  [The  lumen  of  the  acini  is  very 
small,  and,  according  to  Langerhans,  spindle-shaped  or  branched  cells 
(centro-acina/r  cells)  lie  in  it,  and  send  their  processes  between  the 
secretory  ceUs,  thus  acting  as  supporting  cells  for  the  elements  of  the 
wall  of  the  acini]. 

During  secretion,  there  is  a  continuous  change  in  the  appearance  of 
the  cell-substance ;  the  granules  of  the  inner  zone  dissolve  in  the 
secretion ;  the  homogeneous  substance  of  the  outer  zone  is  reversed 
and  transformed  into  granules,  which  pass  towards  the  inner  zone 
(Heidenhain,  Kiihne,  and  Lea). 

Changes  in  the   Cells   during  Digestion.— During  the  first  stage  (6-10 

hours)  the  granular  inner  zone  diminishes  in  size,  the  granules  disappear,  while 
the  striated  outer  zone  increases  in  size  (Fig.  140,  2).  In  the,  second  stage  (10-20 
hours)  the  inner  zone  is  greatly  enlarged  and  granular,  while  the  outer  zone  is 
small  (Fig.  140,  3).  During  hunger  the  outer  zone  agaia  enlarges  (Fig.  140,  1). 
In  a  gland  where  paralytic  secretion  takes  place,  the  gland  is  much  diminished  in 
size,  the  cells  are  shrivelled  (Fig.  140,  4)  and  greatly  changed  (Heidenhain). 
According  to  Ogata,  some  cells  actually  disappear  during  secretion.  When  a 
coloured  injection  is  forced  into  the  duct  under  a  high  pressure,  fine  intercellular 
passages  between  the  secreting  cells  are  formed  (Saviotti's  canals),  but  they  are 
artificial  products. 

Duct. — The  axially-placed  excretory  duct  consists  of  an  inner  thick  and  an 
outer  loose  wall  of  connective  and  elastic  tissues,  lined  by  a  single  layer  of  non- 
striated  columnar  epithelium.  SmaU  mucous  glands  lie  in  the  largest  trunks. 
The  connective-tissue  separates  the  gland  into  lobes  and  lobules.  Non-meduUated 
Tverves,  with  ganglia  in  their  course,  pass  to  the  acini,  but  their  mode  of  termina- 
tion is  unknown.  The  blood-vessels  form  a  rich  capillary  plexus  round  some  acini, 
while  round  others  there  are  very  few.  Kiihne  and  Lea  found  peculiar  small  cells 
in  groups  between  the  alveoli,  and  supplied  with  convoluted  capillaries  like 
glomeruli.  Their  significance  is  entirely  unknown.  [They  are  probably  lym- 
phatic in  their  nature.]  The  lymphatics  resemble  those  of  the  salivary  glands. 
The  pancreas  contains  water,  proteids,  ferments,  fats,  and  salts. 


THE   PANCREATIC   JUICE.  339 

[In  making  experiments  upon  the  pancreatic  secretion,  it  is  important  to  remem- 
ber, that  the  number  of  pancreatic  ducts  varies  in  different  animals.  In  man 
there  is  just  one  duct  opening  along  with  the  common  bile-duct  at  Vater's 
ampulla,  at  the  junction  of  the  middle  and  lower  thirds  of  the  duodenum.  The 
rabbit  has  two  ducts,  the  larger  opening  separately  about  16  inches  below  the 
entrance  of  the  bile-duct.  The  dog  and  cat  have  each  two  ducts  opening 
separately.] 

In  a  gland  which  has  been  exposed  for  some  time,  leucin,  butalanin,  tyrosin, 
often  xanthin  and  guanin  are  found ;  lactic  and  fatty  acids  seem  to  be  formed 
from  chemical  decompositions  taking  place. 

169.  The  Pancreatic  Juice. 

Method  of  obtaining  the  pancreatic  juice.  Regner  de  Graaf  (1664)  tied  a 
cannula  in  the  pancreatic  duct  of  a  dog,  and  collected  the  juice  in  a  small  bag 
placed  in  the  abdomen.  Other  experimenters  brought  the  tube  through  the  abdo- 
minal wall,  and  made  a  temporary  fistula,  which  after  some  days  became  inflamed 
so  that  the  cannula  fell  out.  To  make  a  permanent  fistula,  a  duodenal  fistula 
(like  a  gastric  fistula)  is  made,  and  Wirsung's  duct  is  catheretised  ^\-ith  a  fine  tube ; 
or  the  abdomen  is  opened  (dog),  and  the  pancreatic  duct  is  pulled  forward  and 
stitched  to  the  abdominal  wall,  with  which  in  certain  cases  it  unites. 

The  secretion  obtained  from  a  permanent  fistula  is  a  copious,  slightly 
active,  watery  secretion  containing  much  sodium  carbonate ;  while  the 
thick  fluid  obtained  from  the  fistula  before  inflammation  sets  in  acts 
far  more  energetically.  This  thick  secretion,  which  is  small  in 
amount,  is  the  normal  secretion.  The  copious  watery  secretion  is  per- 
haps caused  by  the  increased  transudation  from  the  dilated  blood- 
vessels (possibly  in  consequence  of  the  paralysis  of  the  vaso-motor 
nerves).  It  is,  therefore,  in  a  certain  sense,  a  "  paralytic  secretion " 
(p.  288).  The  qiiantiii/  varies  much,  according  as  the  fluid  is  thick 
or  thin. 

Dm'ing  digestion,  a  large  dog  secretes  1-1*5  grammes  of  a  thick 
secretion  (CI.  Bernard).  Bidder  and  Schmidt  obtained  in  24  hours 
35—117  grammes  of  a  watery  secretion  per  kilo,  of  a  dog. 

When  the  gland  is  not  secreting,  and  is  at  rest,  it  is  soft,  and  of  a 
pale  yellowish-red  colour,  but  during  secretion  it  is  red  and  turgid 
with  blood,  o^nng  to  the  dilatation  of  the  blood-vessels. 

The  normal  secretion  is  transparent,  colourless,  odourless,  saltish  to 
the  taste,  and  has  a  strong  alkaline  reaction,  owing  to  the  presence  of 
sodium  carbonate,  so  that  when  an  acid  is  added,  COo  is  given  off.  It 
contains  albumin  and  alkaH-albuminate ;  like  thin  white  of  egg  it  is 
sticky,  somewhat  viscid,  flows  with  difliculty,  and  is  coagulated  by  heat 
into  a  wliite  mass.  In  the  cold,  there  separates  a  jelly-Uke  albuminous 
coagulum.  Nitric,  hydrochloric,  and  sulphuric  acids  cause  a  pre- 
cipitate; while  the  precipitate  caused  by  alcohol  is  redissolved  by 
water.     CI.  Bernard  found  in  the  pancreatic  juice  of  a  dog  8 '2  p.c.  of 


340  DIGESTIVE  ACTION   OF  THE   PANCREATIC  JUICE. 

organic  substances,  and  0*8  p.c.  of  ash.     The  juice  (dog)  analysed  by 
Carl  Schmidt  contained  in  1000  parts: — 


[  Organic,       .     .     81  "84  f  Common  Salt, 


Solids,  90-38  in    j  Inorganic,   .     .        8-54 
1,000  parts,    .     j       (like  those  of 

(^  blood-serum), 


Sodic  Phosphate, 

, ,     Sulphate, 
Soda,    .... 
Lime,   .... 
Magnesia,      .     . 
Potassic  Sulphate,        .     0"02 
Ferric  Oxide,      .     .     .     0*02 


7-36 
0-45 
010 
0-32 
0-22 
0-05 


The  more  rapid  and  more  profuse  the  secretion,  the  poorer  it  is  in 
organic  substances  (Weinmann,  Bernstein),  while  the  inorganic  remain 
almost  the  same ;  nevertheless,  the  total  quantity  of  solids  is  greater 
than  when  the  quantity  secreted  is  small  (Bernstein).  Traces  of 
leucin  (Eadziejewski)  and  soaps  are  contained  in  the  fresh  juice.  [It 
usually  contains  few  or  no  structural  elements.  Any  structural 
elements  present  in  the  fresh  juice,  as  well  as  its  proteids,  are  digested 
by  the  peptone-forming  ferment  of  the  juice,  especially  if  the  juice  be 
kept  for  some  time.  If  the  fresh  juice  is  allowed  to  stand  for  some 
time  and  then  mixed  with  chlorine  water,  a  red  colour  is  obtained.] 

Concretions  are  rarely  formed  in  the  pancreatic  ducts ;  they  usually  consist  of 
calcic  carbonate.  Dextrose  has  been;  found  in  the  juice  in  diabetes,  and  urea  in 
jaundice. 

The  statement  made  by  Schiff  that  the  pancreas  secretes  only  after  the  absorp- 
tion of  dextrin  has  not  been  confirmed.  The  secretory  activity  of  the  pancreas  is 
not  dependent  on  the  presence  of  the  spleen. 

170.  Digestive  Action  of  the  Pancreatic  Juice. 

The  presence  of  at  least  four  hydrolytic  ferments  or  enzymes  makes 
the  pancreatic  juice  one  of  the  most  important  digestive  fluids  in  the 
body. 

I.  The  Diastatic  Action  (Valentin,  1844)  is  caused  by  a  diastatic 
ferment,  amylopsin,  a  substance  which  seems  to  be  identical  with  the 
saliva  ferment;  but  it  acts  much  more  energetically  than  the  ptyalin 
of  saliva,  on  raw  starch  as  well  as  upon  boiled  starch ;  at  the  tempera- 
ture of  the  body  the  change  is  effected  almost  at  once,  while  it  takes 
place  more  slowly  at  a  low  temperature.  Glycogen  is  changed  into 
dextrin  and  grape-sugar,  and  achroodextrin  (Briicke's)  into  sugar. 
Even  cellulose  is  said  to  be  dissolved  (Schmulewitsch),  and  gum 
changed  into  sugar  by  it  (v.  Voit), 

According  to  v.  Mering  and  Musculus,  the  starch  (as  in  the  case  of  the  saliva 
p.  294)  is  changed  into  maltose,  a  reducing-dextrin  and  grape-sugar;  so  also  is 
glycogen. 

Amylojjain  changes   achroodextrin   into   maltose ;    at   40°C.    maltose   is  slowly 


DIGESTIVE   ACTION    OF   THE   PANCREATIC   JUICE.  .341 

eliaiigcd  into  dextrose  (Brown  and  Heron),  but  cane-sugar  i-s  not  changed  into 
invertin. 

The  ferment  is  precipitated  by  alcohol,  while  it  is  extracted  by  glycerine  without 
undergoing  any  essential  change.  All  conditions  which  destroy  the  diastatic 
action  of  saliva  (p.  296)  similarly  affect  its  action,  but  the  admixture  with  acid 
gastric  juice  (its  acid  being  neutralised)  or  bile  does  not  seem  to  have  any  injurious 
influence.  This  ferment  is  absent  from  the  pancreas  of  new-born  children 
(Koi'owia).  The  ferment  is  isolated  by  the  same  methods  as  obtain  for  the  saliva- 
ptyalin  (p.  295);  but  the  tryptic  ferment  is  precipitated  at  the  same  time.  The 
addition  of  neutral  salts  (4  p.c.  solution)  e.g.,  potassium  nitrate,  common  salt, 
ammonium  chloride,  increases  the  diastatic  action. 

II.  The  Tryptic  Action  (CI.  Bernard,  1855),  or  the  action  on  pro- 
teids,  depends  upon  the  presence  of  a  hydrolytic  ferment  Avhich 
Corvisart  (1858)  called  pancreatin,  and  W.  Kiihne  (1876)  termed 
trijpsm.  Trypsin  acts  upon  proteids  at  the  temperature  of  the  body, 
when  the  reaction  is  alkaline,  and  changes  them  first  into  a 
globulin-like  body,  propeptone  (p.  331),  and  then  into  a  true  2'>eptonr, 
sometimes  called  tryptone.  The  proteids  do  not  swell  up  before  they 
are  changed  into  peptone.  When  the  proteid  has  been  previously 
swollen  up  by  the  action  of  an  acid,  or  when  the  reaction  of  the 
medium  is  acid,  the  transformation  is  interfered  with.  Gelatin  is 
peptonised  by  it;  but  nuclein  (Bokay)  and  haemoglobin  withstand 
solution  (Hoppe-Seyler).  Trypsin  acts  upon  the  connective-tissues 
just  like  pepsin  (§  166,  III.). 

When  the  trypsin  is  allowed  to  act  upon  the  peptone  formed  by  its 
own  action,  the  peptone  is  partly  changed  into  the  amido-acid,  leucin, 
or  amido-cap-oic  add  (C^jHijNO^),  and  ii/rosin  (CgHjiNOg),  which 
belongs  to  the  aromatic  series  (Kiihne).  Hypoxanthin,  xanthin  (Salo- 
mon) and  asparaginic  acid  (C^H^NO^),  are  also  formed  during  the 
digestion  of  fibrin  and  gluten,  and  so  are  glutaminic  acid  (CgHgNO^), 
amide- valerianic  acid  (CgHj^NOo).  Gelatin  is  first  changed  into  a 
gelatin-peptone,  and  afterwards  is  decomposed  into  glycin  and  ammonia. 

If  the  action  of  the  pancreatic  juice  be  still  further  prolonged,  especi- 
ally if  the  reaction  be  alkaline,  a  body  with  a  strong,  stinking,  disagree- 
able faecal  odour,  indol  (CgH^N),  volatile  fatty  acids,  skatol  (C^Hj^N),  and 
phenol  (CgHgO)  are  formed,  while,  at  the  same  time,  HC02H2SCH^ 
and  N  are  given  off.  The  formation  of  indol  and  the  other  substances  just 
mentioned  depends  upon  putrefaction  (§  184,  III.)  Their  formation  is 
prevented  by  the  addition  of  salicylic  acid  or  thymol,  which  kills  the 
organisms  upon  which  putrefaction  depends  (Hiifner,  Kiihne). 

[If  some  fibrin  be  placed  in  pancreatic  juice,  or  in  a  1  per  cent, 
solution  of  sodium  carbonate  containing  the  ferment  trypsin,  peptones 
are  rapidly  formed.  When  we  compare  gastric  with  pancreatic  digestion, 
we  find  that  there  are  marked  differences.  The  fibrin  in  pancreatic 
digestion  is  eroded,  or  eaten  away,  and  never  swells  up.     The  process 


342 


DIGESTIVE   ACTION    OF    THE    PANCREATIC   JUICE. 


takes  place  in  an  alkaline  medium,  and  never  in  an  acid  one.  In  fact, 
a  1  per  cent,  solution  of  sodium  carbonate  seems  to  play  the  same  part 
in  assisting  trypsin  as  a  "2  per  cent,  solution  of  HCl  does  for  pepsin  in 
gastric  digestion.  In  gastric  digestion  there  is  a  by-product,  syntonin, 
formed  in  addition  to  the  true  peptones.  In  pancreatic  digestion  a 
body  resembling  aUcali-alhumin,  which  passes  into  a  globulin-like  body, 
and  ultimately  into  a  tryptic  peptone,  is  formed.  Of  the  peptones  so 
formed,  one  is  called  anti-peptone,  and  it  is  not  further  changed,  but  part 
of  the  proteid  is  changed  in  a  by-product,  hemi-pe/ptone.  This  body, 
■when  acted  upon,  yields  leucin  and  tyrosin.  When  putrefaction  takes 
place,  the  bodies  above-mentioned  are  also  formed.  We  might  represent 
the  action  of  trypsin  thus  : — 

Proteid  +  trypsin  -f  1  per  cent,  sodium  carbonate,  kept  at  38°  C  = 
formation  of  a  globulin-like  body,  and  then  anti-peptone  and  hemi- 
peptone  are  formed. 


Hemi-peptone 


yields 

yields 

Normal  Digestive 
Products. 

Putrefactive 
Products. 

Leuciu, 
Tyrosin, 
Hypoxanthin, 
Asparaginic  Acid. 

Indol, 

Skatol, 

Phenol, 

Volatile  Fatty  Acids, 

HCO2II2S, 

CH,N. 

Anti-peptone 


Undergoes 
no  further 
change. 


It  seems  that  trypsin  in  pure  water  can  act  slowly  upon  fibrin  to 
produce  peptone.     Pepsin  cannot  do  this  without  the  aid  of  an  acid.] 

When  proteids  are  boiled  for  a  long  time  witli  dilute  H2SO4,  we  obtain  peptone, 
then  leucin  and  tyrosin  (Kuhne) ;  gelatin  yields  glycin.  Hypoxanthin  and  xanthin 
are  obtained  in  the  same  way  by  similarly  boiling  fibrin,  and  the  former  may 
even  be  obtained  by  boiling  fibrin  with  water  (Chittenden). 

It  is  very  remarkable  that  the  juice  of  the  green  fruit  of  the  papaya  tree  (Carica 
papaya)  possesses  digestive  properties  (Poy,  Wittmack),  and  the  action  is  due  to 
an  albuminous  peptonising  ferment,  closely  related  to  trypsin,  and  called  caricin 
or  papain.     The  milky  juice  of  the  fig-tree  has  a  similar  action. 

According  to  Gorup-Besanez,  sprouting  malt,  vetch,  hop,  hemp  during  sprout- 
ing, and  the  receptacle  of  the  artichoke  contain  a  peptonising  ferment. 

Leucin,  tyrosin,  glutaminic  and  asparaginic  acids,  and  xanthin  are  formed  in  the 
seeds  of  some  plants ;  hence  we  may  assume  that  the  processes  of  decomposition  in 
some  seeds  are  closely  allied  to  the  fermentative  actions  that  occur  in  the  intestine 
(Salomon). 

Origin  of  Tr3rpsin. — It  is  formed  within  the  pancreas  from  a  "  motlier- 
suhtance"  or  zymogen    (Heidenhain),    which  takes  up   oxygen.      The 


DIGESTIVE   ACTION    OF   THE   PANCREATIC    JUICE.  343 

zymogen  is  found  in  small  amount,  G  to  10  hours  after  a  meal,  in  the 
inner  zone  of  the  secretory  cells,  but,  after  1 6  hours,  it  is  very  abundant 
in  the  inner  zone  of  the  cells.  It  is  soluble  in  water  and  glycerine. 
Trypsin  is  formed  in  the  watery  solution  from  the  zymogen,  and  the 
same  result  occurs  when  the  pancreas  is  chopped  up  and  treated 
with  strong  alcohol  (W.  Kiihne).  The  addition  of  sodium  chloride, 
carbonate,  and  glycocholate,  favours  the  activity  of  the  trj^tic  ferment 
(Heidenhain). 

[The  following  facts  show  that  zymogen  (t^vjun,  ferment),  or,  as  it  has 
been  called,  trypsinogen,  is  the  precursor  of  trypsin,  that  it  exists  in  the 
gland-cells,  and  requires  to  be  acted  upon  before  trypsin  is  formed.  If 
a  glycerine  extract  be  made  of  a  pancreas  taken  from  an  animal  just 
killed,  and  if  another  extract  be  made  from  a  pancreas  which  has  been 
kept  for  twenty-four  hours,  it  will  be  found  that  an  alkaline  solution  of 
the  former  has  practically  no  effect  on  fibrin,  while  the  latter  is  power- 
fully proteolytic.  If  a  fresh  and  still  warm  pancreas  be  rubbed  up  with 
an  equal  volume  of  a  1  per  cent,  solution  of  acetic  acid,  and  then 
extracted  with  glycerine,  a  powerfully  proteolytic  extract  is  at  once 
obtained.  Trypsin  is  formed  from  zymogen  by  the  action  of  acetic 
acid  (Heidenhain).  There  is  reason  to  believe  that  trypsin  is  formed 
from  zymogen  by  oxidation,  and  that  the  former  loses  its  proteolytic 
power  after  removal  of  its  oxygen.  The  amount  of  zymogen  present 
in  the  gland-cells  seems  to  depend  upon  the  number  and  size  of  the 
granules  present  in  the  inner  granular  zone  of  the  secretory  cells.] 

Trypsin  is  never  absent  from  the  pancreas  of  new-born  children  (Zweifel),  and 
it  may  be  extracted  by  water,  which,  however,  also  dissolves  the  albumin. 
Kiihne  has  carefully  separated  the  albumin  and  obtained  the  ferment  in  a  pure 
state.  It  is  soluble  in  water,  insoluble  in  alcohol.  Pepsin  and  hydrochloric  acid 
together  act  upon  trypsin  and  destroy  it;  hence  it  is  not  advisable  to  administer 
trypsin  by  the  mouth,  as  it  would  be  destroyed  in  the  stomach  (Ewald,  Mays). 

III.  The  action  on  neutral  fats  is  twofold: — (1)  It  acts  upon  fats 
so  as  to  form  Sifine  permanent  emulsion  (Eberle).     (2)  It  causes  fats  to 
take  up  a  molecule  of  water  and  split  into  glycerine  and  fatty  acids: — 
Tristearin.  Water.  Glycerine.  Stearic  Acid. 

(CsrHnoOe)  +  3(H,0)  =  (C3H3O3)  +  3(0,8H3A). 
The  latter  result  is  due  to  the  action  of  an  easily  decomposable  fat- 
splitting  ferment  (CI.  Bernard),  also  called  steapsin.  Lecithin  is  decom- 
posed by  it  into  glycero-phosphoric  acid,  neurin  and  fatty  acids  (Bokay). 
After  the  decomposition  is  completed,  the  fatty  acids  are  saponified 
by  the  alkali  of  the  pancreatic  and  intestinal  juices. 

Emulsification.— The  most  important  change  effected  on  fats  in  the  small 
intestine,  is  the  production  of  an  emulsion,  or  their  sub-division  into  exceedingly 
minute  particles.     This  is  necessary  in  order  that  the  fats  may  be  taken  up  by 


344  SECRETION   OF   PANCREATIC   JUICE. 

the  lacteals.  If  the  fat  to  be  emulsified  contains  a  free  fatty  acid,  i.e.,  if 
it  be  slio-htly  rancid,  and  if  the  fluid  with  which  it  is  mixed  be  alkaline,  emulsifi- 
cation  takes  place  extremely  rapidly  (Brucke).  A  drop  of  cod-liver  oil,  which  in 
its  unpurified  condition  always  contains  fatty  acids,  on  being  placed  in  a  drop  of 
0-3  p.c.  solution  of  soda,  instantly  gives  rise  to  an  emulsion  (Gad).  The  exces- 
sively minute  oil  globules  that  compose  the  emulsion  are  first  covered  with  a 
layer  of  soap,  which  soon  dissolves,  and  in  the  process  small  globules  are  detached 
from  the  original  oil  globules.  The  fresh  surface  is  again  covered  by  a  soap  film, 
and  the  process  is  repeated  over  and  over  again  until  an  excessively  fine  emulsion 
is  obtained  (Gr.  Quincke).  If  the  fat  contain  much  fatty  acid  and  the  solution  of 
soda  be  more  concentrated,  "  myelin-forms"  are  obtained  similar  to  those  which 
are  formed  when  fresh  nerve-fibres  are  teased  in  water  (Brucke).  Animal  oils 
emulsionise  more  readily  than  vegetable  oils;  castor  oil  does  not  emulsionise  (Gad). 

[Pancreatic  Extracts. — The  action  of  the  pancreas  may  be  tested  by  making  a 
watei-y  extract  of  a  perfectly  fresh  gland.  Such  an  extract  always  acts  upon  starch 
and  generally  upon  fats,  but  this  extract  and  also  the  glycerine  extract  vary  in 
their  action  upon  proteids  at  difi'erent  times.  If  the  extract — watery  or  glycerine 
■ — be  made  from  the  pancreas  of  a  fasting  animal,  the  tryptic  action  is  slight  or 
absent,  but  is  active  if  it  be  prepared  from  a  gland  4  to  10  hours  after  a  meal.] 

The  pancreas  of  new-horn  children  contains  trypsin  and  the  fat-decomposing 
ferment,  but  not  the  diastatic  one  (Zweifel).  A  slight  diastatic  action  is  obtained 
after  tM^o  months,  but  the  full  effect  is  not  obtained  until  after  the  first  year 
(Korowin). 

IV.  According  to  Kiihne  and  W,  Eoberts,  the  pancreas  contains  a 
milk- curdling  ferment,  which  may  be  extracted  by  means  of  con- 
centrated solution  of  common  salt. 

171.  Tlie  Secretion  of  the  Pancreatic  Juice. 

As  in  other  glands,  we  distinguish  a  quiescent  state,  during  which 
the  gland  is  soft  and  pale,  and  a  state  of  secretory  activity,  during 
which  the  organ  swells  up  and  appears  pale  red.  The  latter  condition 
only  occurs  after  a  meal,  and  is  caused  probably  in  a  reflex  way  owing 
to  stimulation  of  the  nerves  of  the  stomach  and  duodenum.  Kiihne 
and  Lea  found  that  all  the  lobules  of  the  gland  were  not  active  at 
the  same  time.  The  pancreas  of  the  herbivora  secretes  uninterruptedly 
[but  in  the  dog,  secretion  is  not  constant]. 

Time  of  Secretion. — According  to  Bernstein  and  Heidenhain,  the 
secretion  begins  to  flow  when  food  is  introduced  into  the  stomach,  and 
reaches  its  maximum  2-3  hours  thereafter.  The  amount  falls  to- 
wards the  5  th  or  7  th  hour,  and  rises  again  (owing  to  the  entrance  of  the 
chyme  into  the  duodenum)  towards  the  9th  and  11th  hour,  gradually 
falling  towards  the  17th-24th  hour,  until  it  ceases  completely.  When 
more  food  is  taken  the  same  process  is  repeated.  As  a  general  rule, 
when  the  secretion  occurs  rapidly  it  contains  less  solids  than  when  it 
takes  place  slowly. 

Condition  of  Blood-vessels. — During  secretion,  the  blood-vessels 
behave  like  the  blood-vessels  of  the  salivary  glands  after  stimulation  of 


PEPTONISED   FOOD.  345 

the  chorda — they  dilate,  and  the  venous  blood  is  bright  red — thus, 
it  is  probable  that  a  similar  nervous  mechanism  exists,  [but  as  yet  no 
such  mechanism  has  been  discovered.]  The  secretion  is  excreted  at 
a  pressure  of  more  than  1 7  mm,  Hg.  (rabbit). 

Effect  of  nerves  upon  the  secretion.  The  nerves  arise  from  the 
hepatic,  splenic,  and  superior  mesenteric  plexuses, together  with  branches 
from  the  vagus  and  sympathetic.  The  secretion  is  excited  by  stimula- 
tion of  the  medidla  oblongata  (Heidenhain  and  Landau),  as  well  as 
by  direct  stimulation  of  the  gland  itself  by  induction  shocks  (Kiihne 
and  Lea).  The  secretion  is  suppressed  by  atropin,  by  producing  vomit- 
ing (CI.  Bernard),  by  stimulation  of  the  central  end  of  the  vagus  (C. 
Ludwig  and  Bernstein),  as  well  as  by  stimulation  of  other  sensory 
nerves — e.g.,  the  crural  and  sciatic  (Afanassiew  and  Pawlow).  Extir- 
pation of  the  nerves  accompanying  the  blood-vessels  prevents  the 
above-named  stimuli  from  acting.  Under  these  circumstances  a  thin 
"paralytic  secretion "  with  feeble  digestive  powers  is  formed,  but  its 
amount  is  not  influenced  by  the  taking  of  food  (Bernstein). 

Extirpation  of  the  gland  may  be  performed  (Schiff),  or  the  duct  ligatiu-ed  in 
animals  (Frerichs),  without  causing  any  very  great  change  in  their  nutrition;  the 
absorption  of  fat  from  the  intestine  does  not  cease.  After  the  duct  is  ligatured  it 
may  be  again  restored.  Ligature  of  the  duct  may  cause  the  formation  of  cysts  in 
the  duct  and  atrophy  of  the  gland-substance.  Pigeons  soon  die  after  this  opera- 
tion (Langendorff). 

172.  Preparation  of  Peptonised  Food. 

[Peptonised  food  may  be  given  to  patients  whose  digestion  is  feeble. 
Dr.  Wm.  Roberts,  of  Manchester,  uses  various  forms  of  this  food.  Food 
may  be  peptonised  either  by  peptic  or  tryptic  digestion,  but  the  former 
is  not  so  suitable  as  the  latter,  because  in  peptic  digestion  the  grateful 
odour  and  taste  of  the  food  are  destroyed,  while  bitter  by-products 
are  formed.  Hence,  Dr.  Roberts  employs  pancreatic  digestion,  which 
yields  a  more  palatable  and  agreeable  i^roduct.  As  trypsin  is  destroyed 
by  gastric  digestion,  obviously  it  is  useless  to  give  extract  of  the  pan- 
creas to  a  patient  along  with  his  food. 

Peptonised  Milk. — "A  pint  of  milk  is  diluted  with  a  quarter  of  a  pint 
of  water  and  heated  to  60°  C.  Two  or  three  tea-spoonfuls  of  Benger's 
liquor  pancreaticus,  together  with  10  or  20  grains  of  bicarbonate  of 
soda,  are  then  mixed  therewith."  Keep  the  mixture  at  38°  C.  for  about 
two  hours,  and  then  boil  it  for  two  or  three  minutes,  which  arrests  the 
ferment  action. 

Peptonised  Gruel,  prepared  from  oatmeal,  or  any  farinaceous  food, 
is  more  agreeable  than  peptonised  milk,  as  the  bitter  flavour  does  not 
appear  to  be  developed  in  the  pancreatic  digestion  of  vegetable  proteids. 


346  STRUCTURE   OF  THE  LIVER. 

Peptonised  Milk-Gruel  yielded  Koberts  the  most  satisfactory  results, 
as  a  complete  and  higUy  nutritious  food  for  weak  digestions.  Make  a 
thick  gruel  from  any  farinaceous  food,  e.g.,  oatmeal,  and  while  still  hot 
add  to  it  an  equal  volume  of  cold  milk,  when  the  mixture  will  have  a 
temperature  of  52°C.  (125°F.).  To  each  pint  of  this  mixture,  add  two 
or  three  tea-spoonfuls  of  liquor  pancreaticus  and  20  grains  of  bicarbonate 
of  soda.  It  is  kept  warm  for  two  hours  under  a  "  cosey."  It  is  then 
boiled  for  a  few  minutes  and  strained.  The  bitterness  of  the  digested 
milk  is  almost  completely  covered  by  the  sugar  produced  during  the 
process  (Eoberts). 

Peptonised  soups  and  beef-tea  have  also  been  made  and  used  with 
success,] 

173.  Structure  of  the  Liver. 

The  liver,  the  largest  gland  in  the  body,  consists  of  innumerable 
small  lobules  or  acini,  1-2  millimetres  {^-^2  i^ich)  in  diameter. 
These  lobules  are  visible  to  the  naked  eye.  All  the  lobules  have  the 
same  structure. 

1.  The  Connective-tissue  and  Capsule.— The  liver  is  covered  by  a  thin  fibrous 
firmly  adherent  capsule,  which  has  on  its  free  surface  a  layer  of  endothelium  derived 
from  the  peritoneum.  The  capsule  sends  fine  septa  into  the  organ  betvfeen  the 
lobules,  but  it  is  also  continued  into  the  interior  at  the  transverse  fissure,  where  it 
surrounds  the  portal  vein,  hepatic  artery,  and  bile  duct,  and  accompanies  these 
structures  as  the  Capsule  of  Glisson  or  interlobular  connective-tissue.  The  spaces 
in  which  these  three  structures  lie  are  known  as  portal  canals.  In  some  animals 
(pig,  camel,  polar  bear),  the  lobules  are  separated  from  each  other  by  the  somewhat 
lamellated  connective-tissue  of  Glisson's  capsule,  but  in  man  this  is  but  slightly 
developed,  so  that  adjoining  lobules  are  more  or  less  fused.  Very  delicate  con- 
nective-tissue, but  small  in  amount,  is  also  found  within  the  lobules  (Fleischl, 
Kupffer).    Leucocytes  are  sometimes  found  in  the  tissue  of  Glisson's  capsule. 

2.  Blood-vessels. — («.)  Branches  of  the  Venous  System. — If  the  vena  porta  be 
traced  from  its  entrance  into  the  liver  at  the  portal  fissure,  it  will  be  found  to 
give  off  numerous  branches  lying  between  the  lobules,  and  ultimately  forming 
small  trunks  which  reach  the  periphery  of  the  lobules,  where  they  form  a  rich 
plexus.  These  are  the  interlobular  veins  (Fig.  141,V.  i).  From  these  veins  numerous 
capillaries  (c,  c)  are  given  off  to  the  entire  periphery  of  the  lobule.  The  capillaries 
converge  towards  the  centre  of  the  lobule.  As  they  proceed  inwards,  they  form 
elongated  meshes,  and  between  the  capillaries  lie  rows  or  columns  of  liver-cells 
(d,  d).  The  capillaries  are  relatively  wide,  and  are  so  disposed  as  to  lie  between 
the  edges  of  the  columns  of  cells,  and  never  between  the  surfaces  of  two  neigh-, 
bouring  cells.  The  capillaries  converge  towards  the  centre  of  each  lobule,  where 
they  join  to  form  one  large  vein,  the  intralobular  or  central  vein  (V.  c),  which 
traverses  each  lobule,  reaches  its  surface  at  one  point,  passes  out,  and  joins  similar 
veins  from  other  lobules  to  form  the  sublobular  veins  (V.  s).  These  in  turn  unite 
to  form  wide  veins,  the  origins  of  the  hepatic  veins,  which  open  into  the  vena  cava 
inferior. 

(b.)  Branches  of  the  Hepatic  Artery. — The  branches  of  the  hepatic  artery  accom- 
pany the  branches  of  the  portal  vein  and  bile  duct  in  the  portal  canals  between 
the  lobules,  and  in  their  course  they  give  off  capillaries  to  supply  the  walls  of  the 


STRUCTURE   OF  THE   LIVER. 


347 


portal  vein  and  larger  bile  ducts.  The  branches  of  the  hepatic  artery  anastomose 
frequently  where  they  lie  between  the  lobules.  On  reaching  the  periphery  of  the 
lobules,  a  certain  number  of  capillaries  are  given  off,  which  penetrate  the  lobule 


Fig.  141. 

I,  Scheme  of  a  liver  lobule— V.  i,  V.  i,  interlobular  veins  (portal);  V.  c,  central  or 
intra-lobular  veia  (hepatic) ;  c,  c,  capillaries  between  both  ;  V.  s,  sublobular 
vein ;  V.  v,  vena  vascularis;  A,  A.  branches  of  the  hepatic  artery,  giving  branches, 
r,  r,  to  Glisson's  capsule  and  the  larger  vessels,  and  ultimately  forming  the 
venae  vasculares  at  i,  i,  opening  into  the  intralobular  capillaries  ;  (/,  branches 
of  the  bUe  ducts ;  x,  x,  intralobular  bile  capillaries  between  the  liver-cells ; 
d,  d,  position  of  the  liver-cells  between  the  meshes  of  the  blood  capillaries. 
II,  Isolated  liver-cells — c,  a  blood  capillary;  a,  fine  bile  capillary  channel. 

and  terminate  in  the  capillaries  of  the  portal  vein  {i,  i).  Those  capillaries,  however, 
which  supply  the  walls  of  the  portal  vein  and  large  bile  ducts  (r,  r),  terminate  in 
veins  which  end  in  the  portal  vein  (V.  v — Ferreui). 

Several  branches — capsidar — pass  to  the  surface  of  the  liver,  where  they  form  a 
wide-meshed  plexus  under  the  peritoneum.  The  blood  is  returned  by  veins  which 
open  into  branches  of  the  portal  vein. 

[Pathologists  draw  a  sharp  distinction  between  different  zones  within  a  hepatic 
lobule.  Thus,  the  central  area,  capillaries,  and  cells  are  the  zone  of  the  hepatic  vein, 
which  is  specially  liable  to  cyanotic  changes;  the  area  next  the  periphery  of  the 
lobule  is  the  portal  vein  zone,  whose  cells  under  certain  circumstances  are  particu- 
larly apt  to  undergo  fatty  degeneration;  while  there  is  an  area  lying  midway 
between  the  two  foregoing — the  hepatic  artery  zone — which  is  specially  liable  to 
amyloid  or  waxy  degeneration.] 


348 


STRUCTURE    OF   THE    LIVER. 


o.  The  Hepatic  Cells  (Fig.  141,  II,  a)  are  irregular  polygonal  cells  of  about 
YsVc-th  of  an  inch  (34-45^)  in  diameter  (Fig.  142).  The  arrangement  of  the  capil- 
laries within  a  lobule  determines  the  arrangement  of  the  liver-cells.  The  liver- 
cells  form  anastomosing  columns  which  radiate  from  the  centre  to  the  periphery 
of  each  lobule  (Fig.  143).  [The  liver-cells  are  usually  stated  to  be  devoid  of  an 
envelope,  although  Haycraft  states  that  they  possess  one.  They  usually  contain 
a  single  nucleus  with  one  or  more  nucleoli,  but  sometimes  two  nuclei  occur.  The 
protoplasm  and  nucleus  of  each  cell  contains  a  plexus  of  fibrils  just  like  other 
epithelial  cells.     In  some  animals,  globules  of  oil  and  pigment  granules  are  found 


M"^: 


Fig.  142. 

Human  liver-cells — the  cell  protoplasm  con- 
tains biliary  colouring  matter  and  oil- 
globules  b ;  d,  has  two  nuclei. 


Fig.  143. 

Appearance  of  the  liver- 
cells  after  withholding 
food  for  36  hours. 


in  the  cell  protoplasm  (Fig.  142).]  Each  cell  is  in  relation  with  the  wide-meshed 
blood-capillaries  (d,  d),  and  also  with  the  much  narrower  mesh- work  of  bile 
ducts  (I,  X.) 

It  is  important  to  observe  that  the  appearance  of  the  cells  varies  with  the 
period  of  digestion.  During  hunger,  the  liver  cells  are  finely  granular  and  very 
cloudy  (Fig.  143).  About  13  hours  after  a  full  meal,  especially  of  starchy  food, 
they  contain  coarse  glancing  masses  of  glycogen  (Fig.  144,  2).  The  protoplasm 
near  the  surface  of  the  cell  is  condensed,  and  a  fine  net-work  stretches  towards  the 
centre  of  the  cell,  and  in  it  is  suspended  the  nucleus  (Kupffer,  Heidenhain).  [The 
net-work  within  the  cells  is  best  seen  after  solution  of  the  glycogen.] 

4.  The  bile  ducts. — The  finest  bile  capillaries  or  canaliculi  arise  from  the 
centre  of  the  lobule,  and  indeed  throughout  the  whole  lobule,  they  form  a  regular 
anastomosing  net-work  of  very  fine  tubes  or  channels.  Each  cell  is  surrounded 
by  a  polygonal — usually  hexagonal — mesh  {x,  x).  The  bile  capillaries  always  lie 
in  the  middle  of  the  surfaces  between  two  adjoining  cells  (II,  a),  where  they  form 
actual  intercellular  passages  (Hering).  [According  to  some  observers,  they  are 
merely  excessively  narrow  channels  (1-2  mm.  wide)  in  the  cement-substance 
between  the  cells,  while  according  to  others,  they  have  a  distinct  delicate  wall 
(Fritsch).  The  bile  capillary  net-work  is  much  closer  and  finer  than  the  blood 
capillary  net-work. 

[Thus,  there  are  three  net-works  within  each  lobule — (1)  a  net-work  of  capil- 
laries; (2)  a  net-work  of  hepatic  cells;  (3)  a  net-work  of  bile  capillaries.] 

Excessively  minute  intracellular  i^assages  are  said  to  pass  from  the  bile 
capillaries  into  the  interior  of  the  liver-cells,  where  they  communicate  with  certain 
small  cavities  or  vacuoles  (Asp,  Kupffer,  Pflliger) — (Fig.  144,  3).  As  the  blood 
capillaries  run  along  the  edges  of  the  liver-cells,  and  the  bile  capillaries  between 
the  opposed  surfaces    of   adjacent    cells,  the  two  systems  of  canals  within  the 


STRUCTURE  OF  THE  LIVER.  349 

lobule  are  kept  separate.  Some  bile  capillaries  run  along  the  edges  of  the 
liver-cells  in  the  human  liver,  especially  during  embryonic  life  (Zuckerkandl, 
Toldt). 

Towards  the  peripheral  part  of  the  lobule,  the  bile  capillaries  are  larger,  while 
adjoining  channels  anastomose,  and  leave  the  lobule,  when  they  become  interlobular 
ducts  (jy),  which  join  with  other  similar  ducts  to  form  larger  interlobular  bile  ducts. 
These  accompany  the  hepatic  artery  and  portal  vein,  and  leave  the  liver  at  the 
transverse  fissure.  Th.e  finer  interlobular  ducts  frequently  anastomose  in  Glisson's 
capsule  (Asp),  possess  a  structm-eless  basement  membrane,  and  are  lined  by  a  single 
layer  of  low  polyhedral  epithelial  cells.  The  larrjer  interlobular  ducts  have  a 
distinct  wall  consisting  of  connective  and  elastic  tissue,  mixed  with  circularly 
disposed  smooth  muscular  fibres.  Capillaries  are 
supplied  to  the  wall,  which  is  lined  by  a  single 
layer  of  columnar  epithelium.  A  sub-mucosa  occurs 
only  in  the  largest  bile  ducts,  and  in  the  gall- 
bladder. Smooth  muscular  fibres,  arranged  in  single 
bundles,  occur  in  the  largest  diicts,  and  as  longi-  12  3 

tudiual   and    circular   layers   in    the  gall-bladder,  "Pig,  144, 

whose  mucous  membrane  is  provided  with  numer-  j  Liver-cell  durmg  fasting  • 
ous  folds  and  depressions.  The  epithelium  lining  o,  containing  masses  of  glv- 
the  gall-bladder  is  cylindrical,  with  a  distinct  clear  coc^en  •  3  a  liver-cell  sur- 
disc,  and  between  these  cells  are  goblet  cells.  Small  rounded  with  bile-channels 
branched  tubular  mucous  glands  occur  in  the  large  from  which  fine  twites  pro- 
bile  ducts  and  in  the  gall-bladder.  ceed  into  the  cell-substance 

Vasa  Aberrcmtia  are  isolated  bile  ducts  which  where  they  end  in  vacuole - 
occur  on  the  surface  of  the  liver,  but  have  no  rela-  lii^g  enlargements.  From 
tion  to  any  system  of  liver  lobules.  They  occur  a  rabbit's  liver  injected 
at  the  sharp  margin  of  the  liver,  in  the  region  of  the  with  Berlm  blue  from  the 
inferior  vena  cava,  of  the  gall-bladder,  and  of  the  IjHq  duct, 
parts  near  the  portal  fissure.      It  seems  that  the 

liver  lobules  to  which  they  originally  belonged  have  atrophied  and  disappeared 
(Zuckerkandl  and  Toldt). 

5.  The  Lymphatics  begin  as  pericapillary  tubes  around  the  capillaries  within  the 
lobules  (MacGillavry).  They  emerge  from  the  lobule,  and  run  within  the  -walls  of 
the  branches  of  the  hepatic  and  portal  veins,  and  afterwards  surround  the  venous 
trunks  (Fleischl,  A.  Budge),  thus  forming  the  interlobular  lymphatics.  These 
unite  to  form  larger  trunks,  which  leave  the  liver  partly  at  the  portal  fissure, 
partly  along  with  the  hepatic  veins,  and  partly  at  difterent  points  on  the  surface 
of  the  organ.  There  is  a  narrow  superficial  mesh-work  of  lymphatics  under  the 
peritoneum — sub-peritoneal— ^hich.  communicates  with  the  thoracic  lymphatics 
through  the  triangular  ligament  and  suspensorium,  while  on  the  under  surface,  they 
communicate  with  the  lymphatics  of  the  interlobular  connective  tissue. 

0.  The  Nerves  consist  partly  of  meduUated  and  partly  of  non-medullated  fibres 
from  branches  of  the  sympathetic  and  left  vagus  to  the  hepatic  plexus.  They 
accompany  the  branches  of  the  hepatic  artery,  and  ganglia  occur  on  their  branches 
withua  the  liver.  Some  of  the  nerve-fibres  are  vaso-motor  in  function,  and, 
according  to  Pfluger,  other  nerve-fibres  termmate  directly  in  connection  with 
liver-cells,  although  this  observation  has  still  to  be  confirmed. 

Pathological.— The  connective  tissue  between  the  lobules  may  undergo  gi-eat 
increase  in  amount,  especially  in  alcohol-  and  gin-drinkers,  and  thus  the  substance 
of  the  lobules  may  be  greatly  compressed,  owing  to  the  cicatricial  contraction  of 
the  newly-formed  connective  tissue  (Liver  Cirrhosis).  In  such  interlobular  con- 
nective tissue,  newly-formed  bile  ducts  are  found  (Cornil,  Charcot,  and  others). 

Ligature  of  the  ductus  choledochus,  after  a  time,  causes  interstitial  inflammation 
of  the  liver.     In  rabbits  and  guinea-pigs,  the  liver  parenchyma  disappears,  and  its 


350  CHEMICAL   COMPOSITION    OF   THE   LiVER-CELLS. 

place  is  taken  by  newly-formed  connective  tissue  and  bile  ducts  (Cbarcot  and 
Gombault).  In  all  these  cases  of  interstitial  inflammation,  there  is  proliferation  of 
the  epithelium  of  the  bile  ducts  (Foa,  Salvioli). 

174.  Cliemical  Composition  of  the  Liver-Cells. 

(1.)  Proteids. — The  fresh  soft  parenchyma  of  the  liver  is  alkaline 
in  reaction;  after  death,  coagulation  occurs,  the  cell  contents  appear 
turbid,  the  tissue  becomes  friable,  and  gradually  an  acid  reaction  is 
developed.  This  process  closely  resembles  what  occurs  in  muscle,  and 
is  due  to  the  coagulation  of  a  myosin-like  body,  which  is  soluble  during 
life,  but  after  death  undergoes  spontaneous  coagulation  (P16sz).  The 
liver  contains  other  albuminous  bodies ;  one  coagulating  at  4:5°C,  another 
at  70°C,  and  one  which  is  slightly  soluble  in  dilute  acids  and  alkalies. 
The  cell  nuclei  contain  nuclein  (P16sz).  The  connective  tissue  yields 
gelatin. 

(2.)  Glycogen  or  Animal  Starch — 1-2-2'6  p.c. — is  most  closely 
related  to  inulin,  is  soluble  in  water,  but  diffuses  with  difficulty,  is  a 
true  carbohydrate  (CI.  Bernard  and  v.  Hensen,  1857),  and  has  the 
formula  6(CgH-^Q0g)  +  HgO  (Kiilz  and  Borntrager).  It  is  stored  up 
in  the  liver-cells  (Bock  and  Hoffmann),  in  amorphous  granules  around 
the  nuclei,  but  it  is  not  uniformly  distributed  in  all  parts  of  the  liver 
(v.  Wittich).  Like  inulin,  it  gives  a  deep  red  colour  with  solution  of 
iodine  in  iodide  of  potassium.  It  is  changed  into  dextrin  and  sugar 
(p.  294)  by  diastatic  ferments,  and  when  boiled  with  dilute  mineral 
acids,  it  yields  grape-sugar. 

Preparation  of  Glycogen. — Let  a  rabbit  have  a  hearty  meal,  and  kill  it 
three  or  four  hours  thereafter.  The  liver  is  removed  immediately  after  death; 
it  is  cut  into  fine  pieces,  plunged  in  boiling  water  and  boiled  for  some  time 
in  order  to  obtain  a  watery  extract  of  the  liver-cells.  [It  is  placed  in  boil- 
ing water  to  destroy  the  ferment  present  in  the  liver,  which  would  transform 
the  glycogen  into  grape-sugar.]  To  the  cold  filtrate  are  added  alternately  dilute 
hydrochloric  acid  and  potassio-mercuric  iodide  as  long  as  a  precipitate  occurs.  The 
albuminates  or  proteids  are  precipitated  by  the  iodine  compound  in  the  presence  of 
free  HCl.  It  is  then  filtered,  when  a  clear  opalescent  fluid,  containing  the  glycogen 
in  solution,  is  obtained.  The  glycogen  is  precipitated  from  the  filtrate,  as  a  white 
amorphous  powder,  on  adding  an  excess  of  70-80  p.c.  alcohol.  The  precipitate  is 
washed  with  60  p.c,  and  afterwards  with  95  p.c.  alcohol,  then  with  ether,  and 
lastly,  with  absolute  alcohol;  it  is  dried  over  sulphuric  acid  and  weighed  (Briicke). 

Conditions  which  influence  its  amount. — If  large  quantities  of  starch, 
milk-,  fruit-,  or  cane-sugar,  or  glycerine,  but  not  mannite  or  glycol 
(Luchsinger),  or  inosite  (Kiilz),  be  added  to  the  proteids  of  the  food, 
the  amount  of  glycogen  in  the  liver  is  very  greatly  increased  (to  12 
p.c.  in  the  fowl),  while  a  purely  albuminous  or  purely  fatty  diet 
diminishes  it  enormously.  During  hunger,  it  almost  disappears  (Pavy 
and   Tscherinoff).     The  injection   of   dissolved    carbohydrates   into   a 


CHEMICAL   COMPOSITION   OF  THE  LIVER-CELLS.  351 

mesenteric  vein  of  a  starving  rabbit  causes  the  liver,  previously  free  from 
glycogen,  to  contain  glycogen  (Naunyn). 

During  life,  under  normal  conditions,  the  glycogen  in  the  liver  is 
either  not  transformed  into  grape-sugar  (Pavy,  Ritter,  Eulenberg),  or, 
what  is  more  probable,  only  a  very  small  amount  of  it  is  so  changed. 
The  normal  amount  of  sugar  in  blood  is  0*5-1  per  1000,  although  the 
blood  of  the  hepatic  vein  contains  somewhat  more.  A  considerable 
amount  is  transformed  into  sugar  only  when  there  is  a  decided  de- 
rangement of  the  hepatic  circulation,  and  in  these  circumstances,  the 
blood  of  the  hepatic  vein  contains  more  sugar.  The  glycogen  under- 
goes this  change  very  rapidly  after  death,  so  that  a  liver  which  has 
been  dead  for  some  time  always  contains  more  sugar  and  less  glycogen. 

The  ferment  which  effects  this  change  can  be  obtained  from  the 
extract  of  the  liver-cells  by  the  same  means  as  are  applicable  for  obtain- 
ing other  similar  ferments,  such  as  ptyalin ;  but  it  does  not  seem  to 
be  formed  within  the  liver-cells,  but  only  passes  very  rapidly  from  the 
blood  into  them.  The  ferment  seems  to  be  rapidly  formed  when  the 
blood-stream  undergoes  considerable  derangement  (Ritter,  Schiff).  A 
similar  ferment  is  formed  when  red  blood-corpuscles  are  dissolved 
(Tiegel),  and,  as  there  is  a  destruction  of  red  blood-corpuscles  taking 
place  continually  within  the  liver,  this  is  one  source  from  which  the 
ferment  may  be  formed,  whereby  minute  quantities  of  sugar  would  be 
continually  formed  in  the  liver. 

If  glycogeu  is  injected  into  the  blood,  achroodextrin  appears  in  the  urine,  and 
also  haemoglobin,  as  glycogen  dissolves  red  blood-corpuscles  (Bohm,  Hoifmauu). 

Ligature  of  the  bile  duct  causes  decrease  of  the  glycogen  in  the  liver  (v.  Wittich); 
it  appears  as  if,  after  this  operation,  the  liver  loses  the  property  of  forming  glycogen 
from  the  materials  supplied  to  it. 

(3.)  The  following  substances  have  also  been  found  in  the  liver-cells : — 
Fats  in  the  form  of  highly  refractive  granules  in  the  liver-cells,  as  well 
as  in  the  bile  ducts;  sometimes,  when  the  food  contains  much  fat  (more 
abundant  in  drunkards  and  the  phthisical),  olein,  palmitin,  stearin, 
volatile  fatty  acids,  and  sarcolactic  acid  are  found. 

[Fatty  granules  are  of  common  occurrence  within  the  cells  of  the  liver,  and  when 
they  do  not  occur  in  too  great  amount,  do  not  seem  to  interfere  very  greatly  with 
the  functions  of  the  liver-cells.  These  fatty  granules  are  common  ia  disease,  con- 
stituting fatty  infiltration  and  degeneration,  and  in  such  cases  the  cells  within  a 
lobule  of  the  liver,  next  the  portal  vein,  are  usually  most  highly  charged  with  the 
fatty  particles.  Fatty  particles  occur  if  too  much  fatty  food  be  taken,  and  they 
are  commonly  found  in  the  livers  of  stall-fed  animals,  and  the  well-known  2Mt6-de- 
foie  gras  is  largely  composed  of  the  livers  of  geese,  which  have  been  fed  on  large 
amounts  of  farinaceous  food,  and  which  have  been  subjected  to  other  unfavourable 
hygienic  conditions.  Fatty  granules  are  recognised  by  then-  highly  refractive 
appearance,  by  their  solubility  in  ether,  and  by  being  blackened  by  osmic  acid.] 

There  are  also  found  traces  of  cholesterin,  minute  quantities  of  urea,  uric  acid. 


352  DIABETES   MELLITUS. 

[Leucin  ( ?  guanin),  sarkin,  xanthin,  cystin,   and  tyrosin  occur  pathologically  in 
certain  diseases  where  marked  chemical  decompositions  occur.] 

4.  The  inorganic  substances  found  in  the  human  liver  are — ^potassium, 
sodium,  calcium,  magnesium,  iron,  manganese,  chlorine,  and  phosphoric, 
sulphuric,  carbonic,  and  silicic  acids ;  while  copper,  zinc,  lead,  mercury, 
and  arsenic,  are  accidentally  deposited  in  the  hepatic  tissue. 

175.  Diabetes  Mellitus,  or  Glycosuria. 

The  formation  of  large  quantities  of  grape-sugar  by  the  liver,  and 
its  passage  into  the  blood  (p.  62),  and  from  the  blood  into  the  urine, 
are  related  to  the  above-mentioned  normal  conditions.  Extirpation  of 
the  liver  in  frogs  (Moleschott),  or  destruction  of  the  hepatic  cells  as 
by  fatty  degeneration  from  poisoning  with  phosphorus  or  arsenic 
(Salkowski)  do  not  cause  this  condition.  It  occurs  for  several  hours, 
however,  after  the  injury  of  a  certain  part — the  centre  for  the  hepatic 
vaso-motor  nerves — of  the  floor  of  the  lower  ^art  of  the  fourth  ventricle 
(CI.  Bernard's  piqiire);  also  after  section  of  the  vaso-motor  channels  in 
the  spinal  cord,  from  above  down  to  the  exit  of  the  nerves  for  the 
liver,  viz.,  to  the  lumbar  region,  and  in  the  frog  to  the  fourth  vertebra 
(Schiff).  When  the  vaso-motor  nerves,  which  proceed  from  this  centre 
to  the  liver,  are  cut  or  paralysed  in  any  part  of  their  course,  mellituria 
or  glycosuria  is  produced.  All  the  nerve-channels  do  not  run  through 
the  spinal  cord  alone.  A  number  of  vaso-motor  nerves  leave  the  spinal 
cord  higher  up,  pass  into  the  sympathetic,  and  thus  reach  the  liver;  so 
that  destruction  of  the  superior  (Pavy),  as  well  as  of  the  inferior 
cervical  sympathetic  ganglion,  and  the  first  thoracic  ganglion  (Eckhard), 
of  the  abdominal  ganglia  (Klebs,  Munk),  and  often  of  the  splanchnic 
itseK  (Hensen,  v.  Graefe),  produces  diabetes.  The  paralysis  of  the 
blood-vessels  causes  the  liver  to  contain  much  blood,  and  the  intra- 
hepatic blood-stream  is  slowed.  This  disturbance  of  the  circulation 
causes  a  great  accumulation  of  sugar  in  the  liver,  as  the  blood-ferment 
has  time  to  act  upon  the  glycogen  and  transform  it  into  sugar.  By 
stimulation  of  the  sympathetic  at  the  lowest  cervical  and  first  thoracic 
ganglion,  the  hepatic  vessels  at  the  periphery  of  the  liver  lobules 
become  contracted  and  pale  (Cyon,  AladolT).  It  is  remarkable  that 
glycosuria  when  present  may  be  set  aside  by  section  of  the  splanchnic 
nerves.  This  is  explained  by  supposing  that  the  enormous  dilatation 
and  congestion,  or  the  hypersemia,  of  the  abdominal  blood-vessels 
thereby  produced,  renders  the  liver  anaemic. 

A  number  of  polsOns  which  paralyse  the  hepatic  vaso-motor  nerves  produce 
diabetes  in  a  similar  way — curara  (when  artificial  respiration  is  not  maintained}, 
chloroform,  ether,  chloral,   amyl    nitrite,  carbon  disulphide,  morphia,    mercuric 


SOURCES  OF  GLYCOGEN*.  353 

chloride,  ami  (?)  CO.  But  congestion  of  the  liver  produced  in  other  ways  appears 
to  cause  diabetes — e.g.,  after  mechanical  stimulation  of  the  liver.  To  this  class 
belongs  the  injection  of  dilute  saline  solutions  into  the  blood  (Bock,  Hoffmann), 
■whereby  either  the  change  in  form  or  the  solution  of  the  coloured  blood-corpuscles 
causes  the  congestion.  The  circumstance  that  repeated  blood-letting  makes  the 
blood  richer  in  sugar  may,  perhaps,  be  explained  by  the  slowing  of  the  circulation, 
[Injection  of  a  solution  of  a  neutral  salt  into  a  ligatured  loop  of  the  small  intestine 
sometimes  causes  niellituria  (M.  Hay).] 

Continued  stimulation  of  peripheral  nerves  may  act  reflexly  upon 
the  centre  for  the  vaso-motor  nerves  of  the  liver.  Diabetes  has  been 
observed  to  occur  after  stimulation  of  the  central  end  of  the  vagus  (CI. 
Bernard,  Eckhard,  Kiilz,  Lobeck),  and  also  after  stimulation  of  the 
central  end  of  the  depressor  nerve  (Filehne).  Even  section  and  subse- 
quent stimulation  of  the  central  end  of  the  sciatic  nerve  causes  diabetes 
(SchifF,  Kiilz,  Bohm  and  Hoffmann,  Froning),  and  thus  is  explained 
the  occurrence  of  diabetes  in  people  Avho  suffer  from  sciatica. 

According  to  Schiff,  the  stagnation  of  blood  in  other  vascular  regions  of  the 
body  may  cause  the  ferment  to  accumulate  in  the  blood  to  such  an  exent  that 
diabetes  occui-s.  The  glycosuria  that  occurs  after  compression  of  the  aorta  or 
portal  vein  may  perhaps  be  ascribed  to  this  cause,  but  perhaps  the  pressure  pro- 
duced by  these  procedures  may  paralyse  certain  nerves.  According  to  Eckhard, 
injury  to  the  vermiform  process  of  the  cerebellum  of  the  rabbit  causes  diabetes. 
In  man,  affections  of  the  above-named  nervous  regions  cause  diabetes. 

Theoretical. — In  order  to  explain  the  more  immediate  cause  of  these  pheno- 
mena several  hypotheses  have  been  advanced  : — 

(a.)  The  liver  glycogen  may  be  transformed  unhindered  into  sugar,  as  the  blood 
in  its  passage  through  the  liver  deposits  or  gives  up  the  ferment  to  the  liver- 
cells  (see  above).  So  that  the  normal  function  of  the  vaso-motor  system  of  the 
liver,  and  its  centre  in  the  floor  of  the  fourth  ventricle,  may  be  regarded  as,  in  a 
certain  sense,  an  "  inhibitory  system"  for  the  formation  of  sugar. 

(b.)  If  we  assume  that  under  normal  conditions,  there  is  continually  a  small 
quantity  of  sugar  passing  from  the  liver  into  the  hepatic  vein,  we  might  explain 
the  diabetes  as  due  to  the  disappearance  of  those  decompositions — diminished 
burning-up  of  the  sugar  in  the  blood — which  are  constantly  removing  the  sugar 
from  the  blood.  In  fact,  diabetic  persons  have  been  found  to  consume  less  O 
(v.  Pettenkofer  and  Voit),  and  to  have  an  increased  formation  of  urea. 

Sources  of  Glycogen. — The  ''•  mothcr-suhsfawe  "  of  the  glycogen  of 
the  liver  has  been  variously  stated  to  be  the  carbo-hydrates  of  the  food 
(Pavy),  fats  (olive  oil,  Salomon),  glycerine  (van  Deen,  Weiss),  taurin 
and  glycin  (the  latter  splitting  into  glycogen  and  urea — Heynsius  and 
Kiithe),  the  proteids  (CI.  Bernard),  and  gelatin  (Salomon).  If  it  is 
derived  from  the  albumins,  it  must  be  formed  from  a  non-nitrogenous 
derivative  thereof. 

Effects  of  Food. — Rabbits  whose  livers  have  been  rendered  free 
from  glycogen  by  starvation,  yield  new  glycogen  from  their  livers 
when  they  are  fed  with  cane-sugar,  grape-sugar,  maltose,  or  starch. 
Forced  muscular  movements  soon  make  the  liver  of  dogs  free  from 
glycogen,  and  exposure  to  cold  diminishes  its  amount.     Dextrin  and 

23 


354  OCCURRENCE  OF  GLYCOGEN. 

grape-sugar  occur  in  the  dead  liver  (Limpricht,  Kiik),  but  in  addition, 

some  glycogen  is  found  for  a  considerable  time  after  death,  in  the  liver 

and  in  the  muscles. 

Other  Situations. — Glycogen  is  by  no  means  confined  to  the  liver-cells;  it 
occurs  during  foetal  life  in  all  the  tissues  of  the  body  of  the  embryo,  also  in  young 
animals  (Kiihne),  and  in  the  placenta  (Bernard).  In  the  adult  it  occurs  in  the 
testicle  (Kiihne),  in  the  muscles  (MacDonnel,  0.  Nasse),  in  numerous  pathological 
products,  in  inflamed  lungs  (Kiihne),  and  also  in  the  corresponding  tissues  of  the 
lower  animals.  [It  also  occurs  in  the  chorionic  villi  (CI.  Bernard),  in  colourless 
blood-corpuscles,  in  fresh  pus  cells  which  still  exhibit  amoeboid  movements,  and  in 
fact  in  all  developing  animal  cells,  with  amoeboid  movement;  it  is  a  never-failing 
constituent  in  cartilage,  and  in  the  muscles  and  liver  of  invertebrata,  siich  as 
the  oyster  (Hoppe-Seyler).] 

Persons  suffering  from  diabetes  require  a  large  amount  of  food;  they 
suffer  greatly  from  thirst,  and  drink  much  fluid.  They  exhibit  signs 
of  marked  emaciation,  when  the  loss  of  the  body  is  greater  than  the 
supply.  In  severe  cases  towards  death,  not  unfrequently  a  peculiar 
comatose  condition — diabetic  coma — occurs,  when  the  breath  often  has 
the  odour  of  acetone,  which  is  also  found  in  the  urine  (Fetters).  But 
neither  acetone  nor  its  precursor,  aceto-acetic  acid,  nor  sethyl-diacetic 
acid,  nor  the  unknown  substance,  in  diabetic  urine,  which  gives  the 
red  colour  with  ferric  chloride,  is  the  cause  of  the  coma  (Frerichs  and 
Brieger).  The  urinary  tubules  often  show  the  signs  of  coagulation- 
necrosis,  which  is  recognised  by  a  clear  swollen-up  condition  of  the 
dead  cells  (Ebstein).  As  yet  there  is  no  satisfactory  explanation  of 
those  rarer  cases  of  "acetonsemia"  without  diabetes  (Kanlecti,  Cantini, 
V.  Jacksch). 

176.    The  Functions  of  the  Liver. 

[We  have  still  much  to  learn  regarding  the  functions  of  the  liver,  but 
it  has  two  distinct  functions — one  obvious,  the  other  not.  (1)  The 
liver  secretes  Ule,  which  is  formed  by  the  hepatic  cells,  and  leaves  the 
organ  by  the  bile-ducts,  to  be  poured  by  them  into  the  duodenum. 
(2)  But  the  liver-cells  also  form  glycogen,  which  does  not  pass  into  the 
ducts,  but  in  some,  altered  and  diffusible  form  passes  into  the  blood- 
stream, and  leaves  the  liver  by  the  hepatic  veins.  Hence,  the  study  of 
the  liver  materially  influences  our  conception  of  a  secreting  organ.  In 
this  case,  we  have  the  products  of  its  secretory  activity  leaving  it  by  two 
different  channels — the  one  by  the  ducts,  and  the  other  by  the  blood- 
stream. The  relation  of  the  liver  to  the  blood-corpuscles  has  already 
been  mentioned  (pp.  13-17).] 

177.  Constituents  of  the  Bile. 

Bile  is  a  yellowish  brown  or  dark  green-coloured  transparent  fluid, 
with  a  sweetish  strongly  bitter  taste,    feeble    musk-like   odour  and 


CONSTITUENTS   OF  THE  BILE,  355 

neutral  reaction.  The  specific  gravity  of  human  bile  from  the  gall- 
bladder =  1026-1032,  while  that  from  afistula=  1010-1011  (Jacobsen). 
It  contains: — 

(1.)  Mucus,  which  gives  bile  its  sticky  character,  and  not  unfre- 
quently  makes  it  alkaline,  is  the  product  of  the  mucous  glands  and  the 
goblet-cells  of  the  mucous  membrane  of  the  larger  bile-ducts.  When 
bile  is  exposed  to  the  air,  the  mucus  causes  it  to  putrefy  rapidly.  It  is 
precipitated  by  acetic  acid,  or  alcohol.  [Bile  from  the  gall-bladder, 
when  poured  from  one  vessel  into  another,  shows  the  presence  of  mucin 
in  the  form  of  thin  threads  connecting  the  fluids  in  the  two  vessels. 
When  such  bile  is  treated  with  alcohol,  it  no  longer  exhibits  this 
property,  but  flows  like  a  non-viscid  watery  fluid.  The  bile  formed  in 
the  ultimate  bile-ducts  does  not  seem  to  contain  mucin  or  mucus,  but 
bile  from  the  gall-bladder  always  does.] 

(2.)  The  Bile  Acids. — Glycocholic  and  taurocholic  acids,  so-called 
conjugate  acids,  are  united  with  soda  (in  traces  with  potash)  to  form 
glycocholate  and  taurocholate  of  soda,  which  have  a  bitter  taste.  In 
human  bile  (as  well  as  in  that  of  birds,  many  mammals,  and  amphibians), 
taurocholic  acid  is  most  abundant;  in  other  animals  (pig,  ox)  glyco- 
cholic  acid  is  most  abundant.  These  acids  rotate  the  plane  of  polarised 
light  to  the  right. 

(a.)  Glycocholic  acid,  CgoH^gNOg  (first  discovered  and  described  as 

chohc  acid  by  GmeUn,  and    called,    by  Lehmann,  glycocholic    acid). 

When   boiled  with  caustic  potash,  or  baryta  water,   or  with    dilute 

mineral  acids,  it  takes  up  H._,0  (Strecker,  1848),  and  splits  into — 

Glycin  (=Glycocoll  =  Gelatin  Sugar =Amidoacetic  acid) =C2H5N02. 
+  Cholalic  acid  (also  called  Cholic  acid) .         .         .         =:C24H4o05. 

=  Glycocholic  acid  +  Water      .         .         =C2gH43NOc-I-H20. 

(b.)  Taurocholic  acid,   CaoH^gNSO^,   when  similarly   treated,   takes 

up  water  and  splits  into — 

Taurin  (=  AmidoEethyl-sulphuric  acid)  =  C2H7NS03. 
+  Cholalic  acid     ....         =C24H4o05. 

=: Taurocholic  acid  +  Water  .         .         =C26H45NS07-hH20  (Strecker). 

Preparation  of  the  Bile  acids.— Bile  is  evaporated  to  ^  of  its  volume,  rubbed 
up  into  a  paste  with  excess  of  animal  charcoal,  and  dried  at  100°C.  The  black 
mass  is  extracted  with  absolute  alcohol,  which  is  filtered  until  it  is  clear.  After  a 
part  of  the  alcohol  has  been  removed  by  distillation,  the  bile  salts  are  precipitated 
in  a  resinous  form,  and  on  the  addition  of  excess  of  ether,  there  is  formed  immedi- 
ately a  crystalline  mass  of  glancing  needles  (PZa^^ie/s  "crystallised  bile").  The 
alkaline  salts  of  the  bile  acids  are  freely  soluble  in  water  or  alcohol,  and  insoluble  in 
ether.  Neutral  lead  acetate  precipitates  the  glycocholic  acid— as  lead  glycocholate 
— from  the  solution  of  both  salts  ;  the  precipitate  is  collected  on  a  filter,  dissolved 
in  hot  alcohol,  and  the  lead  is  precipitated  as  lead  sulphide  by  H2S  ;  after  removal 
of  the  lead  sulphide,  the  addition  of  water  precipitates  the  isolated  glycocholic 
acid.     If,  after  precipitating  the  lead  glycocholate,  the  filtrate  be  treated  with 


356  THE    BILE   ACIDS. 

basic  lead  acetate,  a  precipitate  of  lead  taurocholate  is  formed,  from  wMcli  the 
acid  may  be  obtained  in  the  same  way  as  described  above  (Strecker). 

When  human  bile  is  similarly  treated,  instead  of  the  "crystallised  bile,"  a 
resinous  non-crystalline  precipitate  is  obtained.  Boiling  with  baryta  water  isolates 
the  cholalic  acid  from  it,  which  is  obtained  from  its  barium  salt  by  adding  hydro- 
chloric acid.  When  dissolved  in  ether,  it  occurs  in  the  form  of  prismatic  crystals 
if  petroleum-ether  is  added.  The  anthropocJiolic  acid  (C18H28O4 — H.  Bayer),  so 
obtained  is  not  soluble  in  water,  but  readily  so  in  alcohol,  and  rotates  the  ray  of 
polarised  light  to  the  left. 

With  regard  to  the  decomposition  products  of  the  bile  acids,  glycin, 
as  such,  does  not  occur  in  the  body,  but  only  in  the  bile  in  combination 
with  cholalic  acid,  in  urine  in  combination  with  benzoic  acid,  as 
hippuric  acid,  and  lastly,  in  gelatin  in  complex  combination. 

Cholalic  acid  rotates  the  ray  of  polarised  light  to  the  right,  and  its 
chemical  composition  is  unknown  (perhaps  it  is  to  be  regarded  as 
benzoic  acid,  in  which  a  complex  of  atoms  similar  to  oleic  acid  is  intro- 
duced— Hoppe-Seyler).  It  occurs  free  only  in  the  intestine,  where  it  is 
derived  from  the  splitting  up  of  taurocholic  acid,  and  it  passes  in  part 
into  the  faeces.  It  is  insoluble  in  water,  soluble  in  alcohol,  but  soluble 
with  difficulty  in  ether,  from  which  it  separates  in  prisms.  Its 
crystalline  alkaline  salts  are  readily  soluble  in  water. 

Cholalic  acid  is  replaced  in  the  bile  of  many  animals  by  a  nearly  related  acid, 
e.g.,  in  pig's  bile,  by  hyo-cholalic  acid  (Strecker,  Gundlach);  in  the  bile  of  the 
goose,  cheno-cholalic  acid  is  present  (Marsson,  Otto). 

When  cholalic  acid  is  boiled  with  concentrated  HCl,  or  dried  at 
200°C,  it  becomes  an  anhydride,  thus: — 

Cholalic  acid    .      =  C24H40O5,  produces 

Choloidinic  acid     =  C24H3804-f-H20,  and  this  again  yields 

Dyslysin   .         .     =  C24H3603  =  H20. 

(Choloidinic  acid  is,  however,  not  improbably  a  mixture  of  cholalic  acid  and 
dyslysin ;  dyslysin,  when  fused  with  caustic  potash,  is  changed  into  cholalate 
of  potash— Hoppe-Seyler),  If  anthropocholic  acid  be  heated  to  185°C,  it  gives  up 
1  molecule  of  water,  and  yields  anthropochol-dyslysin  (Bayer). 

By  oxidation  cholalic  acid  yields  a  tribasic  acid,  as  yet  uninvestigated,  and  a 
fair  amount  of  oxalic  acid,  but  no  fatty  acids  (Cleve). 

Pettenkofer's  Test.— The  bile  acids,  cholalic  acids,  and  their  anhy- 
drides, when  dissolved  in  water,  yield  on  the  addition  of  |  concentrated 
sulphuric  acid  (added  in  drops  so  as  not  to  heat  the  fluid  above  70°C), 
and  several  drops  of  a  10  p.c,  solution  of  cane-sugar,  a  reddish  purple 
transparent  fluid,  which  shows  two  absorption-bands  at  E  &  F  (Schenk), 

[A  very  good  method  is  to  mix  a  few  drops  of  the  cane-sugar  solu- 
tion with  the  bile,  and  to  shake  the  mixture  until  a  copious  froth  is 
obtained.  Pour  the  sulphuric  acid  down  the  side  of  the  test-tube,  and 
then  the  characteristic  colour  is  seen  in  the  froth,] 

According  to  Drechsel,  it  is  better  to  add  phosphoric  acid,  instead  of  sulphuric 


THE   BILE   PIGMENTS.  357 

acid,  until  the  fluid  is  syrupy,  then  add  the  cane-sugar,  and  afterwards  place  the 
whole  in  boiling  water.  When  investigating  the  amount  of  bile  acids  in  a  liquid, 
the  albumin  must  be  removed  beforehand,  as  it  gives  a  reaction  similar  to  the 
bile  acids,  but  in  that  case  the  red  fluid  has  only  one  absorption-band.  If  only 
small  quantities  of  bile  acids  are  present,  the  fluid  must  in  the  first  place  bo 
concentrated  by  evaporation. 

The  origin  of  the  bile  acids  takes  place  within  the  liver.  After  its 
extirpation,  there  is  no  accumulation  of  biliary  matters  in  the  blood 
(Joh.  Muller,  Kundc,  Moleschott). 

How  the  formation  of  the  nitrogenous  bile  acids  is  effected  is  quite  unknown. 
They  must  be  obtained  from  the  decomposition  of  albuminous  materials,  and  it  ia 
important  to  note  that  the  amount  of  bile  acids  is  increased  by  albuminous  food. 

Taurin  contains  the  sulphur  of  albumin  ;  bile  salts  contains  4-4'6  p.c.  of  sulphur 
(Voit),  which  may  perhaps  be  derived  from  the  stroma  of  the  dissolved  red  blood- 
corpuscles. 

(3.)  The  Bile  Pigments.— The  freshly  secreted  bile  of  man  and  many 
animals  has  a  yellowish-brown  colour,  due  to  the  presence  of  bilirubin 
(Stadler).  When  it  remains  for  a  considerable  time  in  the  gall-bladder 
or  when  alkaline  bile  is  exposed  to  the  air,  the  bilirubin  absorbs  0  and 
becomes  changed  into  a  green  pigment,  biliverdin.  This  substance  is 
present  naturally,  and  is  the  chief  pigment  in  the  bile  of  herbivora 
and  cold-blooded  animals. 

(a.)  Bilirubin  (CagHaeNiOg)  is,  according  to  Stadler  and  Maly, 
perhaps  united  with  an  alkali;  it  crystallises  in  transparent  fox-red 
clinorhombic  prisms.  It  is  insoluble  in  water,  soluble  in  chloroform,  by 
which  substance  it  may  be  separated  from  biliverdin,  which  is  in- 
soluble in  chloroform.  It  unites  as  a  monobasic  acid  with  alkalies,  and 
as  such  is  soluble.  It  is  identical  with  Virchow's  hgematoidin 
(p.  35). 

Preparation.— It  is  most  easily  prepared  from  the  red  (bilirubiii-chalk)  gall- 
stones of  man  or  the  ox.  The  stones  are  pounded,  and  their  chalk  dissolved 
by  hydrochloric  acid  ;  the  pigment  is  then  extracted  with  chloroform. 

That  bilirubin  is  derived  from  hfemoglobin  is  very  probable,  considering  its 
identity  with  hsematoidin.  Very  probably  red  blood-corpuscles  are  dissolved  in 
the  liver,  and  their  ha3moglobin  changed  into  bilirubin. 

(b.)  Biliverdin  (Heintz),  CgaHggN^Og,  is  simply  an  oxidised  derivative 
of  the  former,  from  which  it  can  be  obtained  by  various  oxidation 
processes.  It  is  readily  soluble  in  alcohol,  very  slightly  so  in  ether 
and  not  at  all  soluble  in  chloroform.  It  occurs  in  considerable 
amount  in  the  placenta  of  the  bitch.  As  yet  it  has  not  been  retrans- 
formed  by  reducing  agents  into  bilirubin. 

Tests  for  Bile  Pigments.— Bilirubin  and  biliverdin  may  occur  in 
other  fluids — e.g.,  the  urine,  and  are  detected  by  the  Gmelin-Heintz' 
reaction.  When  nitric  acid  containing  some  nitrous  acid  is  added  to  the 
liquid  containing  these  pigments,  a  play  of  colours  is  obtained,  begin- 
ning with  green   (biliverdin),  blue,  violet,  red,  ending  with  yellow. 


358 


CHOLESTERIN. 


[ThivS  reaction  is  best  done  by  placing  a  drop  of  the  liquid  on  a  white 
porcelain  plate,  and  adding  a  drop  of  the  impure  nitric  acid.] 

(c. )  If  when  the  blue  colour  is  reached,  the  oxidation  process  is  arrested,  blli- 
Cy  anin  (Heynsius,  Campbell),  in  acid  solution  blue,  (in  alkaline  violet)  is  obtained, 
which  shows  two  ill-de&ied  absorption-bands  near  D  (Jaff^.  Capranica  advises 
that  the  acid  fluids  be  shaken  with  a  mixture  of  chloroform  and  alcohol  (1:1). 
This  mixture  absorbs  the  pigment ;  pour  off  the  fluid  and  add  bromine  in  alcohol 
(4  p.c),  and  the  play  of  colour  is  obtained. 

(d- )  Bilifuscill  occurs  in  small  amount  in  decomposing  bile  and  in  gall-stones 
= bilirubin + HgO. 

(e.)  Biliprasin  (Stadler)  also  occurs  =  bilirubin  +  HgO  +  0. 
(/,)  The  yellow  pigment,  which  results  from  the  prolonged  action 
of  the  oxidising  reagent,  is  the  choletelin  (CisHigNgOg)  of  Maly ;  it  is 
amorphous,  and  soluble  in  water,  alcohol,  acids,  and  alkalies, 

(g)  Hydro-bilirubin. — Bilirubin  absorbs  H  +  HgO  (by  putrefaction, 
or  by  the  treatment  of  alkaline  watery  solutions  with  the  powerfully 
reducing  sodium  amalgam),  and  becomes  converted  into  Maly's  hydro- 
bilirubin  (C32H14N4O7),  which  is  slightly  soluble  in  water,  and  more 
easily  soluble  in  solutions  of  salts,  or  alkalies,  alcohol,  ether,  chloroform, 
and  shows  an  absorption-band  at  h,  F.  This  substance,  which,  accord- 
ing to  Hammarsten,  occurs  in  normal  bile,  is  a  constant  colouring- 
matter  of  faeces,  and  was  called  stercobilin  by  Vaulair  and  Masius,  but 
is  identical  with  hydro-bilirubin  (Maly).  It  is,  however,  probably 
identical  with  the  urinary  pigment  urobilin  of  Jaff6  (Stokvis,  p.  35). 
(4.)  Cholesterin,  C26H44O  (HgO)    is    an  alcohol  which   rotates   the 

ray  of  polarised  light  to  the 
left,  and  whose  constitution  is 
unknown;  it  occurs  also  in 
blood,  yelk,  nervous  matter,  and 
[gall-stones].  It  forms  trans- 
parent rhombic  plates,  which 
usually  have  a  small  oblong 
piece  cut  out  of  one  corner 
(Fig.  145,  a).  It  is  insoluble  in 
water,  soluble  in  hot  alcohol,  in 
ether,  and  chloroform.  It  is 
kept  in  solution  in  the  bile  by 
the  bile  salts. 

Preparation.— It  is  most  easily 
prepared  from  so-caUed  white  gall- 
stones, which  not  unfrequently  con- 
sist almost  entirely  of  cholesterin,  by 
extracting  them  with  hot  alcohol  after 
they  are  pulverised.  Crystals  are 
excreted  after  evaporation  of  the 
alcohol,  and  they  give  a  red  colour 


Crystals     of 
laminated  ; 


partially  injured  forms ; 
after  Wedl). 


Fig.  145. 

Cholesterin  —  a,    regularly 
b,    irregularly    laminated, 
X  300  (Aitken 


THE   SECRETION    OF   BILE,  359 

with  sulphuric  acid  (5  vol.  to  1  vol.  HgO— Moleschott),  while  they  give  a  blue- 
as  cellulose  does— with  sulphuric  acid  and  iodine.  When  dissolved  in  chloro- 
form, 1  drop  of  concentrated  sulphuric  acid  causes  a  deep  red  colour  (H.  Schifif). 

(5.)  Amongst  the  other  organic  constituents  of  bile  are: — Lecithin 
(p.  36),  or  its  decomposition  product,  neurin  (cholin),  and  glycero- 
phosphoric  acid  (into  which  lecithin  may  be  artificially  transformed  by 
boiling  with  baryta);  Pahnitin,  Stearin,  Olein,  as  well  as  their  soda 
soaps ;  Diastatic  Ferment  (Jacobson,  v.  Wittich) ;  traces  of  Urea 
(Picard);  (in  ox  bile,  acetic  acid  and  propionic  acid,  united  with 
glycerine  and  metals,  Dogiel). 

[The  proportion  of  diastatic  ferment  is  not  greater  than  in  the  tissues  of  the 
body  generally  (M.  Hay).] 

(6.)  Inorganic  constituents  of  bile  (0*6  to  1  p.c): — 

They  are— sodium  chloride,  potassium  chloride,  calcic  and  magnesic  phosphate, 
and  much  iron,  which  in  fresh  bile  gives  the  ordinary  reactions  for  iron,  so  that 
iron  must  occur  in  one  of  its  oxidised  compounds  in  bile  (Kunkel);  manganese  and 
silica.  Freshly  secreted  bile  contains  in  the  dog  more  than  50  vol.,  and  in  the 
rabbit  109  vol.  per  cent.  CO2  (Pfluger,  Boguljubow,  Charles),  partly  united  to 
alkalies,  partly  absorbed,  the  latter,  however,  being  almost  completely  absorbed 
within  the  gall-bladder. 

The  mean  composition  of  human  bile  is  : — 


Lecithin,  .        .        0-5    p.c. 

Mucin,     .         .        .        1-3    „ 
Ash,         .        .        .        0-61   „ 


Water,   .        .  82-90  p.c. 

Bile  Salts,  .  6-11    „ 

Fats  and  Soaps,  .  2       „ 

Cholesterin,    .  .  0-4      „ 

Farther,  unchanged  fat  probably  always  passes  into  the  bile,  but  is 
again  absorbed  therefrom  (Virchow).  The  amount  of  S  in  dry  dog's 
bile  =  2-8-3-l  p.c,  the  N  =  7-10  p.c.  (Spiro);  the  sulphur  of  the  bile  is 
not  oxidised  into  sulphuric  acid,  but  it  appears  as  a  sulphur-compound 
in  the  urine  (Kunkel,  v.  Voit). 

178.  Secretion  of  Bile. 

The  secretion  of  bile  is  not  a  mere  filtration  of  substances  already 
existing  in  the  blood  of  the  liver,  but  it  is  a  chemical  production  of  the 
characteristic  biliary  constituents,  accompanied  by  oxidation,  within  the 
hepatic  cells,  to  which  the  blood  of  the  gland  only  supplies  the  raw 
material.  The  liver-cells  themselves  undergo  histological  changes 
during  the  process  of  digestion  (Heidenhain,  Kayser).  It  is  secreted 
continually;  it  is  partly  stored  up  in  the  gall-bladder,  and  is  poured 
out  copiously  during  digestion. 

The  higher  temperature  of  the  blood  of  the  hepatic  vein,  as  well 
as  the  large  amount  of  CO2  in  the  bile  (Pfluger),  indicate  that 
oxidations  occur  within  the  liver.     The  water  of  the  bile  is  not  merely 


360  CONDITIONS  INFLUENCING    THE   SECRETION    OF  BILE. 

filtered  through  the  blood-capillaries,  as  the  pressure  within  the  bile- 
ducts  may  exceed  that  in  the  portal  vein. 

(2.)  The  quantity  of  bile  was  estimated  by  v.  Wittich  from  a  biliary 
fistula,  at  533  cubic  centimetres  in  24  hours  (some  bile  passed  into  the 
intestine);  by  Westphalen,  at  453-566  grms.;  [by  Murchison,  at  40 
oz.];  Joh.  Ranke,  on  a  biliary-pulmonary  fistula,  at  652  cubic  centi- 
metres. The  last  observation  gives  14  grms.  (with  0-44  grms.  solids) 
per  kilo,  of  man  in  24  hours. 

Analogous  values  for  animals  are— 1  kilo,  dog,  32  grm.  (1-2  solids)— Kblliker, 
H.  Miiller;  1  kilo,  rabbit,  137  grm.  (2-5  solids)— Bidder  and  Schmidt;  1  kilo, 
guinea-pig,  176  grms.  (5-2  solids)— Bidder  and  Schmidt. 

(3.)  The  excretion  of  bile  into  the  intestine  shows  two  maxima 
during  one  period  of  digestion;  the  first,  from  3  to  5  hours,  and  the 
second,  from  13  to  15  hours  after  food.  The  cause  is  due  to  simul- 
taneous reflex  excitement  of  the  hepatic  blood-vessels,  which  become 
greatly  dilated. 

(4.)  The  influence  of  food  is  very  marked.  The  largest  amount  is 
secreted  after  a  flesh  diet,  with  some  fat  added  ;  less  after  vegetable 
food;  a  very  small  amount  with  a  pure  fat  diet;  it  stops  during 
hunger.  Draughts  of  water  increase  the  amount,  with  a  correspond- 
ing relative  diminution  of  the  solid  constituents. 

(5.)  The  influence  of  blood  supply  is  variable  : — 

(a.)  Secretion  is  gi'eatly  favoured  by  a  copious  and  rapid  blood  supply.  The 
blood-pressure  is  not  the  prime  factor,  as  ligature  of  the  cava  above  the  diaphragm, 
whereby  the  greatest  blood-pressure  occurs  in  the  liver,  arrests  the  secretion 
(Heidenhain). 

(h.)  Simultaneous  ligature  of  the  hepatic  artery  (diameter  5^  mm.)  and  the 
portal  vein  (diameter  6  mm.)  abolishes  the  secretion  (Rbhrig).  These  two  vessels 
supply  the  raw  material  for  the  secretion  of  bile. 

(c.)  If  the  hepatic  artery  be  ligatured,  the  portal  vein  alone  supports  the 
secretion  (Simon,  Schiff,  Schmulewitsch,  Asp).  According  to  Kotbmeier,  Betz, 
Cohnheim  and  Litten,  ligature  of  the  artery  or  one  of  its  branches  ultimately 
causes  necrosis  of  the  jjarts  supplied  by  that  branch,  and  eventually  of  the  entire 
liver,  as  this  artery  is  the  nutrient  vessel  of  the  liver. 

{d.)  If  the  branch  of  the  portal  vein  to  one  lobe  be  ligatured,  there  is  only  a 
slight  secretion  in  that  lobe,  so  that  the  bile  must  be  formed  from  the  arterial 
blood  (Schmulewitsch  and  Asp).  Complete  ligature  of  the  portal  vein  rapidly 
causes  death.  [The  blood-pressure  falls  rapidly  and  the  blood  accumulates  in  the 
blood-vessels  of  the  abdomen.  In  fact,  the  accumulation  of  the  blood  within  the 
abdomen  takes  place  to  so  great  an  extent,  that  practically  the  animal  is  bled 
into  its  own  abdomen  (p.  176).] 

Neither  the  ligature  of  the  hepatic  artery  by  itself  (Schiff,  Betz),  nor  the 
gradual  obliteration  of  the  portal  vein  by  itself,  causes  the  cessation  of  the 
secretion,  but  it  is  diminished.  That  sudden  ligature  of  the  portal  vein  causes 
cessation  is  explained  by  the  fact,  that  in  addition  to  diminution  of  the  secretion, 
the  enormous  stagnation  of  blood  in  the  rootlets  of  the  portal  vein  in  the  abdominal 
organs  makes  the  liver  very  anaemic,  and  thus  prevents  it  from  secreting. 

{e.)  If  the  blood  of  the  hepatic  artery  is  allowed  to  pass  into  the  portal  vein 
(which  has  been  ligatured  on  the  peripheral  side),  secretion  continues  (Schiff). 


BILIARY  FISTUL.E.  361 

(/.)  Profuse  loss  of  blood  arrests  the  secretion  of  bile,  before  the  muscular  and 
nervous  apparatus  become  paralysed.  A  more  copious  supply  of  blood  to  other 
organs — e.g. ,  to  the  muscles  of  the  trunk — during  vigorous  exercise,  diminishes  the 
secretion,  while  the  transfusion  of  large  quantities  of  blood  increases  it  (Landois); 
but  if  too  high  a  pressure  is  caused  in  the  jiortal  vein,  by  introducing  blood  from 
the  carotid  of  another  animal,  it  is  diminished  (Heidenhain). 

(g-)  The  influence  of  nerves.— All  conditions  which  cause  contraction  of  the 
abdominal  blood-vessels — e.g.,  stimulation  of  the  ansa  Vieussenii,  of  the  inferior 
cervical  ganglion,  of  the  hepatic  nerves  (Afanassiew)  of  the  splanchnics,  of  the 
spinal  cord  (either  directly  by  strychnia,  or  reflexly  through  stimulation  of  sensory 
nerves)  affect  the  secretion;  and  so  do  all  conditions  which  cause  stagnation  or 
congestion  of  the  blood  in  the  hepatic  vessels  (section  of  the  splanchnic  nerves, 
diabetic  puncture,  §  175),  section  of  the  cervical  spinal  cord  (Heidenhain).  Par- 
alysis (ligature)  of  the  hepatic  nerves  causes  at  first  an  increase  of  the  biliary 
secretion  (Afanassieff), 

(h.)  With  regard  to  the  raw  material  sui)plied  to  the  liver  by  its  blood-vessels, 
it  is  important  to  note  the  difference  in  the  composition  of  the  blood  of  the  hepatic 
and  portal  veins.  The  blood  of  the  hepatic  vein  contains  more  sugar  (?),  lecithin, 
cholesterin  (Drosdoff),  and  blood-corpuscles,  but  less  albumin,  fibrin,  hpemoglobin, 
fat,  water,  and  salts. 

(6.)  The  formation  of  bile  is  largely  dependent  upon  the  decomposi- 
tion of  coloured  blood-corpuscles,  as  they  supply  the  material  necessary 
for  the  formation  of  some  of  its  constituents. 

Hence,  all  conditions  which  cause  solution  of  the  coloured  blood-corpuscles  are 
accompanied  by  an  increased  formation  of  bile  (§  180). 

(7.)  Of  course  a  normal  condition  of  the  hepatic  cells  is  required  for 
a  normal  secretion  of  bile. 

Biliary  Fistulae.— The  mechanism  of  the  biliary  secretion  is  studied  in  animals 
by  means  of  biliary  fistulse.  Schwann  opened  the  belly  by  a  vertical  incision  a 
little  to  the  right  of  the  ensiform  process,  cut  into  the  fundus  of  the  gall-bladder, 
and  sewed  its  margins  to  the  edges  of  the  wound  in  the  abdomen,  and  afterwards 
introduced  a  cannula  into  the  wound.  As  a  rule  all  the  bile  is  discharged  extei-nally; 
but  to  be  quite  certain  that  this  is  so,  the  common  bile-duct  ought  to  be  tied  between 
two  ligatures,  and  divided.  After  a  fistula  is  freshly  made  the  secretion  falls. 
This  depends  upon  the  removal  of  the  bile  from  the  body.  If  bile  be  supplied  the 
secretion  is  increased.  Regeneration  of  the  divided  bile-duct  may  occur  in  dogs. 
v.  Wittich  observed  a  biliary  fistula  in  man.  [A  tempurary  biliary  fistula  may  also 
be  made.  The  abdomen  is  opened  in  the  same  way  as  described  above.  A  long 
bent  glass  cannula  is  introduced  and  tied  into  the  common  bile-duct,  and  the  cystic 
duct  is  ligatured  or  clamped.  The  tube  is  brought  out  through  the  wound  in  the 
abdomen.     Necessarily  all  the  bile  must  be  discharged  by  the  tube]. 

179.  Excretion  of  Bile, 

[In  connection  with  the  excretion  of  bile,  we  must  keep  in  view  two 
distinct  mechanisms.  (1)  The  hik-secreting  mechanism  dependent  upon 
the  liver-cells,  which  are  always  in  a  greater  or  less  degree  of  activity; 
(2)  the  bile-expelling  mechanism,  which  is  specially  active  at  certain 
periods  of  digestion  (p,  360).] 


362  EXCRETION   OF   BILE. 

This  occurs — (1.)  Owing  to  the  continual  pressure  of  the  newly- 
formed  bile  within  the  interlobular  bile-ducts  forcing  onward  the  bile 
in  the  excretory  ducts. 

(2.)  Owing  to  the  interrupted  periodic  com/pression  of  the  liver  from 
above,  by  the  diaphragm,  at  every  inspiration.  Farther,  every  inspira- 
tion assists  the  flow  of  blood  in  the  hepatic  veins,  and  every  respiratory 
increase  of  pressure  within  the  abdomen  favours  the  current  in  the 
portal  vein. 

It  is  probable  that  the  diminution  of  the  secretion  of  bile,  which  occurs  after 
bilateral  division  of  the  vagi,  is  to  be  explained  in  this  way;  still  it  is  to  be 
remembered,  that  the  vagus  sends  branches  to  the  hepatic  plexus.  It  is  not  decided 
whether  the  biliary  excretion  is  diminished  after  section  of  the  phrenic  nerves  and 
paralysis  of  the  abdominal  muscles. 

(3.)  Owing  to  the  contraction  of  the  smooth  muscles  of  the  larger  bile- 
ducts  and  the  gall-bladder.  Stimulation  of  the  spinal  cord,  from  which 
the  motor  nerves  for  these  structures  pass,  causes  acceleration  of  the 
outflow,  which  is  afterwards  followed  by  a  diminished  outflow  (Heiden- 
hain,  J.  Munk).  Under  normal  conditions,  this  stimulation  seems  to 
occur  reflexly,  and  is  caused  by  the  passage  of  the  ingesta  into  the 
duodenum,  which,  at  the  same  time,  excites  movement  of  this  part  of 
the  intestine. 

(4.)  Direct  stimulation  of  the  liver  (Pfliiger),  and  reflex  stimulation 
of  the  spinal  cord  (Eohrig),  diminish  the  excretion ;  while  extirpation 
of  the  hepatic  plexus  (Pfliiger),  and  injury  to  the  floor  of  the  fourth 
ventricle  (Heidenhain)  do  not  exert  any  disturbing  influence. 

(5.)  A  relatively  small  amount  of  resistance  causes  bile  to  stagnate 
in  the  bile-ducts. 

A  manometer,  tied  into  the  gall-bladder  of  a  guinea-pig,  supports  a  column  of 
200  millimetres  of  water;  and  secretion  can  take  place  under  this  pressure 
(Heidenhain,  Friedlander,  Barisch).  If  this  pressure  be  increased,  or  too  long 
sustained,  the  watery  bile  passes  from  the  liver  into  the  blood,  even  to  the  amount 
of  four  times  the  weight  of  the  liver,  thus  causing  solution  of  the  red  blood- 
corpuscles  by  the  absorbed  bile ;  and  very  soon  thereafter,  hsemoglobin  appears  in 
the  urine. 

180.  Reabsorption  of  Bile. 

Phenomena  of  Jaundice  (Icterus;  Cholaemia). 

Absorption  Jaundice. — When  an  impediment  or  resistance  is  offered  to  the 
outflow  of  bile  into  the  intestine — e.g.,  by  a  plug  of  mucus,  or  a  gall-stone 
which  occludes  the  bile-duct,  or  where  a  tumour  or  pressure  from  without,  makes  it 
impervious — the  bile-ducts  become  filled  with  bile  and  cause  an  enlargement  of  the 
liver.  The  pressure  within  the  bile-ducts  is  increased.  As  soon  as  the  pressure 
has  reached  a  certain  amount,  which  it  soon  does  when  the  bile-duct  is  occluded 
(in  the  dog  275  mm.  of  a  column  of  bile — Afanassiew)— reabsorption  of  bile  from 
the  distended  larger  bile-ducts  takes  place  into  the  lymphatics  (not  the  blood- 


PHENOMENA    OF   JAUNDICE.  363 

vessels)  of  the  liver  (Saunders,  1795);  the  bile  acids  pass  into  the  lymphatics  of  the 
liver.  [The  lymphatics  can  be  seen  at  the  portal  fissure  filled  with  a  deep  yellow- 
coloured  lymph].  The  lymph  passes  into  the  thoracic  duct,  and  so  into  the  blood 
(Fleischl,  Kunkel,  Kufferath).  Even  when  the  pressure  is  very  low  within  the 
portal  vein,  bUe  may  pass  into  the  blood,  without  any  obstruction  to  the  bile-duct 
being  present.  This  is  the  case  in  Jctertts  neonatorum,  as  after  ligature  of  the 
umbilical  cord,  no  more  blood  passes  through  the  umbilical  vein;  farther,  in  the 
icterus  of  hunger,  as  the  portal  vein  is  relatively  emptj',  owing  to  the  feeble  absorp- 
tion from  the  intestinal  canal  (CI.  Bernard,  Voit,  Naunyn). 

II.  Chola?mia  may  also  occur,  owing  to  the  excessive  production  of  bile  (hjrper- 
cholia),  the  bile  not  being  all  excreted  into  the  intestine,  so  that  part  of  it  is 
reabsorbed.  This  takes  place  when  there  is  solution  of  a  gi'eat  number  of  blood- 
corpuscles  (§  ITS,  6),  which  yields  material  for  the  formation  of  bile.  Thick 
inspissated  bile  accumulates  in  the  bile-ducts,  so  that  stagnation,  with  subsequent 
reabsorption  of  the  bile,  takes  place  (Afanassiew).  The  transfusion  of  heterogeneous 
blood  by  dissolving  coloured  blood-corpuscles  acts  in  this  direction  (p.  201). 
Icterus  is  a  common  phenomenon  after  too  copious  transfusion  of  the  same  blood. 
The  blood-corpuscles  are  dissolved  by  the  injection  into  the  blood  of  heterogeneous 
blood-serum  (Landois),  by  the  injection  of  bile  acids  into  the  vessels  (Frerichs), 
and  by  other  salts,  by  phosphoric  acid,  water  (Herrmann),  chloral,  inhalation  of 
chloroform,  and  ether  (Nothnagel,  Bernstein);  the  injection  of  dissolved  hcemo- 
globin  into  the  arteries  (Kiihne),  or  into  a  loop  of  small  intestine,  acts  in  the  same 
way  (Naunyn). 

Icterus  Neonatonim. — When,  owing  to  compression  of  the  placenta  within 
the  uterus,  too  much  blood  is  forced  into  the  blood-vessels  of  the  newly-born 
infant,  a  part  of  the  sui'plus  blood  during  the  first  few  days  becomes  dissolved, 
whereby  the  haemoglobin  passes  into  bilirubin,  thus  causing  jaundice  (Virchow, 
Violet). 

When  the  jaundice  is  caused  by  the  absortion  of  bile  already  formed 
in  the  liver,  it  is  called  hepatogenic  or  absorption-jaundice.  The 
following  are  the  symptoms  : — 

Phenomena. — (l-)  Bile  pigments  and  bile  acids  pass  into  the  tissues  of  the 
body  ;  hence,  the  most  pronounced  external  symptom  is  the  yellowish  tint  or 
jaundice.  The  skin  and  the  sclerotic  become  deeply  coloured  yellow.  In  preg- 
nancy the  fcetus  is  also  tinged. 

(2.)  Bile  pigments  and  bile  acids  pass  into  the  urine  (not  into  the  saliva,  tears,  or 
mucus),  and  their  presence  is  ascertained  by  the  usual  tests  (§  177).  When  there 
is  much  bile  pigment,  the  urine  is  coloured  a  deep  yellowish  brown,  and  its  froth 
is  citron  yellow;  while  strips  of  gelatin  or  paper  dipped  into  it  also  become 
coloured.     Occasionally  bilirubin  ( =  hsematoidin)  crystals  occur  in  the  urine. 

(3.)  The  fffices  are  -^  clay  co/o?»-efZ "  (because  the  hydrobilirubin  of  the  bile  is 
absent  from  the  frecal  matter) — very  hard  (because  the  fluid  of  the  bile  does  not 
pass  into  the  intestine) ;  contain  much  fat  (in  globules  and  crystals),  because  the 
fat  is  not  sufficiently  digested  in  the  intestine  without  bile,  so  that  more  than 
60  p.c.  of  the  fat  taken  with  the  food  reappears  in  the  fteces  (v.  Voit)  ;  they  have 
a  very  disagreeable  odour,  because  bile  normally  greatly  limits  the  putrefaction  in 
the  intestine.  The  evacuation  of  the  faces  occurs  sloivhj,  partly  owing  to  the  hard- 
ness of  the  fiBces,  partly  because  of  the  absence  of  the  peristaltic  movements  of  the 
intestine,  owing  to  the  want  of  the  stimulating  action  of  the  bile. 

(4.)  The  heai't-beats  are  greatly  diminished,  e.g.,  to  40  per  minute.  This  is  due 
to  the  action  of  the  bile  salts,  which  at  first  stimulate  the  cardiac  ganglia,  and  then 
weaken  them.  The  injection  of  bile  salts  into  the  heart,  produces  at  first  a  tem- 
porary acceleration  of  the  pulse  (Landois),  and  afterwards  slowing  (Rohrig).     The 


364  EFFECTS   OF   DRUGS   ON   THE   SECRETION    OF  BILE. 

same  occurs  wlieii  they  are  injected  into  the  blood,  but  in  this  case,  the  stage  of 
excitement  is  very  short.  The  phenomenon  is  not  affected  by  section  of  the  vagi. 
It  is  probable,  that  when  the  action  of  the  bile  salts  is  long  continued  they  act 
upon  the  heart-muscle  (Traube).  In  addition  to  the  action  on  the  heart,  there  is 
elcufing  of  thi  rt:<XAroi'wn.  and  dminution  of  temperature. 

(5).  That  the  nervous  system,  and  perhaps  also  the  muscles,  are  affected,  either  by 
the  bile  salts  or  by  the  accumulation  of  cholesterin  in  the  blood  (Fliut,  K.  Miiller), 
is  shown  by  the  very  general  relaxation,  sensation  of  fatigue,  weakness  and 
drowsiness,  lastly  deep  coma — sometimes  there  is  sleeplessness,  itchiness  of  the 
skin,  even  mania,  and  spasms.  Lowit,  after  injecting  bile  into  animals,  observed 
phenomena  referable  to  stimulation  of  the  respiratory,  cardio-inhibitory,  and  vaso- 
motor nerve-centres. 

(6.)  In  very  pronoimced  jaundice,  there  may  be  "  yellovj  vision"  (Lucretius 
Carus),  owing  to  impregnation  of  the  retina  and  macula  lutea  with  the  bile  pig- 
ment. 

(7.)  The  bile  acids  in  the  blood  dissolve  the  red  blood-corpuscles.  The  hsemo- 
globin  is  changed  into  new  bile  pigment,  and  the  globuUn-like  body  of  the 
haemoglobin  may  form  urinary  cylinders  or  casts  in  the  urinary  tubules 
(Xothnagel),  which  are  ultimately  washed  out  of  the  tubules  by  the  urine. 

Passage  of  substances  into  tlie  Bile- —Various  substances  pass  into  the 
bile,  such  substances  being  in  the  blood,  viz. ,  the  metals  (v.  Sartoris,  Mohnheini, 
Orfila)— copper,  lead,  zinc,  nickel,  silver,  bismuth  0^'ichert),  arsenic,  antimony, 
iron  ;  these  substances  are  also  deposited  in  the  hepatic  tissues.  Potassium  iodide, 
bromide,  and  sulphocyanide  (Peiper),  and  turpentine  also  pass  into  the  bile,  and,  to 
a  less  degree,  cane-sugar  and  grape-sugar  (Mosler) ;  sodium  salicylate,  and  carbolic 
acid  (Peiper).  If  a  large  amount  of  water  be  injected  into  the  blood,  the  bile 
becomes  albuminous  (Mosler);  mercuric  and  mercurous  chlorides  cause  an  increase 
of  the  water  of  the  bile  (G.  Scott).  Sugar  has  been  found  in  the  bUe  in  diabetes  ; 
leucin  and  tyrosin  in  typhus,  lactic  acid  and  albumin  in  other  pathological 
conditions  of  this  fluid. 

Clnflnence  of  Drugs  on  tlie  Secretion  of  Bile.— Two  methods  are  adopted, 

one  by  means  of  permanent  fistula,  and  the  other  by  establishing  temporary 
tistulae.  The  latter  is  the  more  satisfactorjr  method,  and  the  experiments  are 
usually  made  on  fasting  curarised  dogs.  A  suitable  cannula  is  introduced  into  the 
common  bUe-duct,  as  described  at  p.  361,  the  animal  is  curarised,  artificial 
respiration  being  kept  up,  while  the  drug  is  injected  into  the  stomach  or  intestine. 
Piohrig  used  this  method,  which  was  improved  by  Pvutherford  and  Vignal.  Rbhrig 
found  that  some  purgatives,  croton  oil,  colocynth,  jalap,  aloes,  rhubarb,  senna, 
and  other  substances,  increased  the  secretion  of  bile.  Pvutherford  and  Vignal 
investigated  the  action  of  a  large  number  of  drugs  on  the  bile-secreting  mechanism. 
They  found  that  croton  oil  is  a  feeble  hepatic  stimulant,  while  podophyllin,  aloes, 
colchicum,  euonymin,  iridin,  sanguinartn,  ipecacuan,  colocynth,  sodium  phosphate, 
phjiiolaccin,  sodium  benzoate,  sodium  salicylate,  dilute  nitrohydrochloric  acid, 
ammonium  phosphate,  mercuric  chloride  (corrosive  sublimate),  are  aU  powerftil,  or 
very  considerable,  hepatic  stimulants.  They  found  that  some  substances  stimulate 
the  intestinal  glands,  but  not  the  liver,  e.g.,  magnesitim  sulphate,  castor  oil, 
gamboge,  ammonium  chloride,  manganese  sulphate,  calomel.  Other  substances 
stimulate  the  liver  as  well  as  the  intestinal  glsinds,  although  not  to  the  same  extent, 
e.g.,  Bcammony  (povs'erful  intestinal,  feeble  hepatic  stimulant) ;  colocynth  excites 
both  powerfully;  jalap,  sodium  sulphate,  baptisin,  act  with  considerable  power 
both  on  the  liver  and  the  intestinal  glands.  Calabar  bean  stimulates  the  liver,  and 
the  increased  secretion  caused  thereby  may  be  reduced  by  sulphate  of  atropin, 
although  the  latter  drug,  when  given  alone,  does  not  notably  affect  the  secretion 
of  bile.  The  injection  of  water  or  bile  slightly  increases  the  secretion.  In  all 
cases  where  purgation  was  produced  by  purely  intestinal  stimulants,   such  as 


FUNCTIONS   OF  THE   BiLE.  365 

magnesium  sulphate,  gamboge,  and  castor  oil,  the  secretion  of  bile  was  diminished. 
In  all  such  experiments  it  is  most  important  that  the  temperature  of  the  animal  he 
kept  up  by  covering  it  with  cotton  wool,  else  the  secretion  of  bile  diminishes. 

As  yet,  we  cannot  say  definitely  whether  these  substances  stimulate  the  secretion 
of  bile,  by  exciting  the  mucous  membrane  of  the  duodenum  or  other  part  of  the  small 
intestine,  and  thereby  inducing  reflex  excitement  of  the  liver.  Their  action  does 
not  seem  to  be  due  to  increase  of  the  blood- stream  through  the  liver.  More  pro- 
bably, as  Rutherford  suggests,  these  drugs  act  directly  on  the  hepatic  cells  or 
their  nerves.  Acetate  of  lead  directly  depresses  the  biliary  secretion,  while  some 
substances  affect  it  indirectly.] 

Cholesteraemia.— Flint  ascribes  great  importance  to  the  excretion  of  cholesterin 
by  the  bile,  with  reference  to  the  metabolism  of  the  nerv^ous  system.  Cholesterin, 
which  is  a  normal  ingredient  of  nervous-tissue,  is  excreted  by  the  bile  ;  and  if  it  be 
retained  in  the  blood,  "cholesterEemia,"  with  grave  nerv^ous  symptoms,  is  said  to 
occur.  This,  however,  is  problematical,  and  the  phenomena  described  are  probably 
referable  to  the  retention  of  the  bile  acids  in  the  blood. 

181.  Functions  of  the  Bile. 

[(1)  Bile  is  concerned  in  the  digestion  of  certain  food-stuffs; 

(2)  part  of  it  is  absorbed; 

(3)  part  is  excreted.] 

(A.)  Bile  plays  an  important  part  in  the  absorption  of  fats : — 
(1.)  It  eimdsionises  neutral  fats  (§  170,  III.),  whereby  the  fatty  granules 
pass   more  readily  through  or  between  the  cylindrical  epithelinm  of 
the  small  intestine  into  the  lacteals.     It  does  not  decompose  neutral 
fats  into  glycerine  and  a  fatty  acid,  as  the  pancreas  does. 

When,  however,  fatty  acids  are  dissolved  in  the  bile  (Lenz)  the  bile  salts  are 
decomposed,  the  bile  acids  being  set  free,  while  the  soda  of  the  decomposed  bile  salts 
readily  forms  a  soluble  soap  with  the  fatty  acids.  These  soaps  are  soluble  in  the 
bile,  and  increase  considerably  the  emulsifying  power  of  this  fluid.  Bile  can 
dissolve  directly  fatty  acids  to  form  an  acid  fluid,  which  has  high  emulsionising 
properties  (Steiner). 

(2.)  As  fluid  fat  flows  more  rapidly  through  capillary  tubes  when  they 
are  moistened  with  bile,  it  is  concluded  that  when  the  pores  of  the 
absorbing  wall  of  the  small  intestine  are  moistened  with  bile,  the 
fatty  particles  pass  more  easily  through  them. 

(3.)  Filtration  of  fat  takes  place  through  a  membrane  moistened 
with  bile  or  bile  salts  under  less  pressure  than  when  it  is  moistened 
Avith  water  or  salt  solutions  (v.  Wistinghausen). 

(4.)  As  bile,  like  a  solution  of  soap,  has  a  certain  relation  to  watery 

solutions,  as  well  as  to  fats,  it  permits  diffusion  to  take  place  between 

these  two  fluids,    as    the   membrane  is   moistened  by  both  fluids   (v. 

"Wistinghausen), 

It  is  clear,  therefore,  that  the  bile  is  of  great  importance  in  the  preparation  and 
in  the  absorption  of  fats.  This  is  forcibly  illustrated  by  experiments  on  animals, 
in  which  the  bile  is  entirely  discharged  externally  through  a  fistula.  Dogs,  under 
these  conditions,  absorbed  at  most  40  p.c.  of  the  fat  taken  with  the  food  (v.  Voit). 


366  FUNCTIONS    OF  THE   BILE. 

The  chyle  of  such  animals  is  very  poor  in  fat,  is  not  white  but  transparent;  the 
faeces,  however,  contain  much  fat,  and  are  oily.  Such  animals  are  voracious 
(Nasse);  the  tissues  cf  the  body  contain  little  fat,  even  when  the  nutrition  of  the 
animals  has  not  been  much  interfered  with.  Persons  suffering  from  disturbances 
of  the  biliary  secretion,  or  from  liver  affections,  ought,  therefore,  to  abstain  from 
fatty  food. 

(B.)  Fresh  bile  contains  a  diastatic  ferment  which  transforms  starch 
into  sugar  (Nasse,  Jacobson,  v.  Wittich),  and  also  glycogen  into  sugar 
(BufaHni). 

(C.)  Bile  excites  controxtions  of  the  muscular  coats  of  the  intestine,  and 
contributes  thereby  to  absorption. 

(1.)  The  bile  acids  act  as  a  stimulus  to  the  muscles  of  the  villi,  which  contract 
from  time  to  time,  so  that  the  contents  of  the  lymph-spaces  [origins  of  the 
lacteals]  are  emptied  towards  the  larger  lymphatics,  and  the  villi  are  thus  in  a 
position  to  absorb  more  (Schiff).  [The  villi  act  like  numerous  small  pumps,  and 
expel  their  contents,  which  are  prevented  from  returning  by  the  presence  of  valves 
in  the  larger  lymphatics.] 

(2. )  The  musculature  of  tli,e  intestine  itself  seems  to  be  excited,  perhaps  through 
the  agency  of  the  plexus  myentericus.  In  animals  with  a  biliary  fistula,  and  in 
which  the  bile-duct  is  obstructed,  the  intestinal  peristalsis  is  greatly  diminished, 
while  the  salts  of  the  bile  acids  administered  by  the  mouth  cause  diarrhoea  and 
vomiting  (Leyden,  Schiilein).  As  contraction  of  the  intestine  aids  absorption, 
bile  is  also  necessary  in  this  way  for  the  absorption  of  the  dissolved  food  stuffs. 

(D.)  The  bile  moistens  the  walls  of  the  intestine,  as  it  is  copiously 
excreted.  It  gives  to  the  faeces  their  normal  amount  of  water,  so  that 
they  can  be  readily  evacuated.  Animals  with  biliary  fistula,  or  persons 
^vith  obstruction  of  the  bile-ducts,  are  very  costive.  The  mucus  of  the 
bile  aids  the  forward  movement  of  the  ingesta  through  the  intestinal 
canal.     [Thus,  in  a  certain  sense,  bile  is  a  natural  imrgative^ 

(E.)  The  bile  diminishes  putrefactive  decomposition  of  the  intestinal 
contents  (Valentin).     [Thus,  it  is  an  antiseptic] 

(F.)  When  the  strongly  acid  contents  of  the  stomach  pass  into  the 
duodenum,  the  glycochoHc  acid  is  precipitated  by  the  gastric  acid,  and 
carries  the  pepsin  with  it  (Burkart).  Some  of  the  albumin,  which  has 
been  simply  dissolved,  but  as  yet  not  peptonised,  is  also  precipitated, 
but  it  does  not  seem  that  peptone  or  propeptone  are  precipitated  by  the 
mixture  of  the  bile  acids  (Maly  and  Emich).  The  bile  salts  are  decom- 
posed by  the  acid  of  the  gastric  juice.  When  the  mixture  is  rendered 
alkaline  by  the  pancreatic  juice  and  the  alkali  derived  from  the  decom- 
position of  the  bile  salts,  the  pancreatic  juice  acts  energetically  in  this 
alkaline  medium  (Moleschott). 

When  bile  passes  into  the  stomach,  as  in  vomiting,  the  acid  of  the  gastric  juice 
unites  with  the  bases  of  the  bile  salts;  so  that  sodium  chloride  and  free  bile  acids 
are  formed,  and  the  acid  reaction  is  thereby  somewhat  diminished.     The  bile 


FATE   OF   THE    BILE    IN    THE   INTESTINE.  3G7 

acids  are  not  effective  for  carrying  on  gastric  digestion;  the  peptone  is  precipitated 
by  them;  neutralisation  also  causes  a  precipitate  of  pepsin  and  mucin.  As 
soon,  however,  as  the  walls  of  the  stomach  secrete  new  acid,  the  pepsin  is  redis- 
solved.  The  bile  which  passes  into  the  stomach  deranges  gastric  digestion,  by 
shrivelling  the  proteids,  which  can  only  be  peptonised  when  they  are  swollen  up. 

182.  Fate  of  the  Bile  in  the  Intestine. 

Some  of  the  biliary  constituents  are  completely  evacuated  with  the 
faeces,  while  others  are  reabsorbed  by  the  intestinal  walls. 

(1.)  Mucin  passes  unchanged  into  the  fseces. 

(2.)  The  bile  pigments  are  reduced,  and  are  partly  excreted  with  the 
fseces  as  hydroUlirubin  (§  177,  3  ^),  and  partly  as  the  identical  end-product 
urobilin  by  the  urine. 

Hydrobilirubin  is  absent  from  MeCOnium,  while  bilirubin  and  biliverdin  and 
an  unknown  red  oxidation  product  of  it  are  present  (Zweifel).  Hence,  no  reduc- 
tion—but rather  oxidation — processes  occur  in  the  fostal  intestine  (Hoppe-Seyler). 

(3.)  Cholesterin  is  given  oif  with  the  faces. 

(4.)  The  bile  salts  are  for  the  most  part  reabsorbed  by  the  walls  of 
the  jejunum  and  ileum,  to  be  re-employed  in  the  animal's  economy. 
Tappeiner  found  them  in  the  chyle  of  the  thoracic  duct — minute  quan- 
tities pass  from  the  blood  into  the  urine.  Only  a  very  small  amount 
of  glycocholic  acid  appears  unchanged  in  the  faeces.  The  taurocholic 
acid,  as  far  as  it  is  not  absorbed,  is  easily  decomposed  in  the  intestine, 
by  the  putrefactive  processes,  into  cliolalic  acid  and  taurin ;  the  former 
of  these  is  found  in  the  faeces,  but  the  taurin  at  least  seems  not  to  be 
constantly  present. 

As  putrefactive  decomposition  does  not  occur  in  the  fcetal  intestine,  unchanged 
taurocholic  acid  is  found  in  meconium  (Zweifel).  The  anhydride  stage  of  cliolalic 
acid  (the  artificially  prepared  choloidinic  acid  ?),  dyslysin,  is  an  artificial  product, 
and  does  not  occur  in  the  faeces  (Hoppe-Seyler). 

(5.)  The  faeces  contain  mere  traces  of  Lecithin  (Wegscheider,  Bokay). 

The  greatest  part  of  the  most  important  biliary  constituents,  the  bile  acids, 
re-enter  the  blood,  and  thus  is  explained  why  animals  with  a  biliary  fistula, 
where  all  the  bile  is  removed  (without  the  animal  being  allowed  to  lick  the  bile), 
rapidly  lose  weight.  This  depends  partly  upon  the  digestion  of  the  fats  being 
interfered  with,  and  also  upon  the  direct  loss  of  the  bile  salts.  If  such  dogs  are 
to  maintain  their  weight,  they  must  eat  twice  as  much  food.  In  such  cases,  carbo- 
hydi-ates  most  beneficially  replace  the  fats.  If  the  digestive  apparatus  is  other- 
wise intact,  the  animals,  on  account  of  their  voracity,  may  even  increase  in  weight, 
but  the  flesh  and  not  the  fat  is  increased. 

The  fact  that  bile  is  secreted  during  the  foetal  period,  whilst  none  of 
the  other  digestive  fluids  is,  proves  that  it  is  an  excretion. 

The  cholalic  acid  which  is  reabsorbed  by  the  intestinal  walls  passes  into  the 
body,  and  seems  ultimately  to  be  burned  to  form  CO2  and  H2O.    The  glycin  (with 


368  THE   INTESTINAL  JUICE. 

hippuric  acid)  forms  urea,  as  the  urea  is  increased  after  the  injection  of  glycin 
(Horsford,  Schultzen,  Nencki).  The  fate  of  taurin  is  unknown.  When  large 
quantities  are  introduced  into  the  human  stomach,  it  reappears  in  the  urine,  as 
tauro-carbonic  acid,  along  with  a  small  quantity  of  unchanged  taurin.  When 
injected  subcutaneously  into  a  rabbit,  nearly  all  of  it  reappears  in  the  urine. 

183.  The  Intestinal  Juice. 

The  human  intestine  is  ten  times  longer  than  the  length  of  the  body,  as 
measured  from  the  vertex  to  the  anus.  It  is  longer  comparatively  than  that  of 
the  omnivora  (Hemiing).  Its  minimum  length  is  507,  its  maximum  1,149  centi- 
metres; its  capacity  is  relatively  greater  in  children  (Beneke).  In  childhood  the 
absorptive  elements,  in  adults  the  secreto-chemical  processes,  appear  to  be  most 
active  (Baginsky). 

The  succus  entericus  is  the  digestive  fluid  secreted  by  the  numerous 
glands  of  the  intestinal  mucous  membrane.  The  largest  amount  is 
produced  by  Lieberkiihn's  glands,  while  in  the  duodenum,  there  is 
added  the  scanty  secretion  of  the  small  compound  tubular  Brunner's 
glands. 

Brunner's  glands  are  small  convoluted,  branched,  tubular  glands,  lying  in 
the  sub-mucosa  of  the  duodenum.  Their  fine  ducts  run  inwards,  pierce  the 
mucous  membrane,  and  open  at  the  bases  of  the  villi.  The  acini  are  lined  by 
cylindrical  cells,  like  those  lining  the  pyloric  glands.  In  fact,  Brunner's  glands 
are  structurally  and  anatomically  identical  with  the  pyloric  glands  of  the  stomach. 
During  himger,  the  cells  are  turbid  and  small,  while  during  digestion  they  are 
large  and  clear.     The  glands  receive  nerve-fibres  from  Meissner's  plexus  (Drasch). 

I.  The  Secretion  of  Brunner's  Glands.— The  granular  contents  of  the 
secretory  cells  of  these  glands,  which  occur  singly  in  man,  but  form 
a  continuous  layer  in  the  duodenum  of  the  sheep,  besides  albuminous 
substances,  consist  of  mucin  and  a  ferment-substance  of  unknown  consti- 
tution. The  watery  extract  of  the  glands  causes: — (1)  Solution  of 
proteids  at  the  temperature  of  the  body  (Krolow).  (2)  It  also  has  a 
diastatic  (?)  action.  It  does  not  appear  to  act  upon  fats.  [Brown  and 
Heron  have  shown  that  the  secretion  of  Brunner's  glands,  more  actively 
than  any  other  glands  of  the  intestines,  converts  maltose  into  glucose.] 

On  account  of  the  smallness  of  the  objects,  such  experiments  are  only  made 
with  great  difficulty,  and,  therefore,  there  is  a  certain  amount  of  uncertainty  with 
regard  to  the  action  of  the  secretion. 

Lieberkiihn's  glands  are  simple  tubular  glands  resembling  the  finger  of  a 
glove  [or  a  test  tube],  which  lie  closely  packed,  vertically  near  each  other,  in  the 
mucous  membrane;  they  are  most  numerous  in  the  large  intestine,  owing  to  the 
absence  of  villi  in  this  region.  They  consist  of  a  structureless  membrana  propria 
lined  by  a  single  layer  of  low  cylindrical  epithelium,  between  which  numerous 
goblet-cells  occur,  the  goblet-cells  being  fewer  in  the  small  intestine  and  much 
more  numerous  in  the  large  (Fig.  146).  The  glands  of  the  small  intestine  yield  a 
thin  secretion,  while  those  of  the  large  intestine  yield  a  large  amount  of  sticky 
mucus  from  their  goblet-cells  (Klose  and  Heidenhain). 


CHARACTERS   OF  THE   INTESTINAL  JUICE. 


369 


II.  The  Secretion  of  Lieberkiihn's  glands  is,  from  the  duodenum 
onwards,  the  chief  constituent  of  the  intestinal  juice. 

Intestinal  Fistula.— The  intestinal  juice  is  obtained  by  making  a  Thiry's 
fistula  (1864).  A  loop  of  the  intestine  of  a 
dog  is  pulled  forward,  and  a  piece  about 
four  inches  in  length  is  cut  out,  so  that 
the  continuity  of  the  intestinal  tube  is  broken, 
but  the  mesentery  and  its  blood-vessels  are  not 
divided.  One  end  of  this  tube  is  closed,  and 
the  other  end  is  left  open  and  stitched  to  the 
abdominal  wall.  After  the  two  ends  of  the 
intestine,  from  which  this  piece  was  taken,  have 
been  carefully  brought  together  with  sutures, 
so  as  to  establish  the  continuitj'  of  the  intestinal 
canal,  animals  still  continue  to  live.  The  excised 
piece  of  intestine  yields  a  secretion  which 
is  uncontaminated  with  any  other  digestive 
secretion. 

[Thiry's  method  is  very  unsatisfactory,  as 
judged  from  the  action  of  the  separated  loop  in 
relation  to  medicaments,  probably  owing  to 
its  mucous  membrane  becoming  atrophied 
from  disuse,  or  injured  by  inflammation. 
Meade  Smith  has  lately  used  a  better  method, 
in  which  he  makes  a  small  opening  in  the 
intestine,  through  which  he  introduces  two 
small  hollow  and  collapsed  india-rubber  balls, 
one  above  and  the  other  below  the  opening, 
which  are  then  distended  by  inflation  until  they 
completely  block  a  certain  length  of  the 
intestine.  The  loop  thus  blocked  off  having 
been  previously  well  washed  out,  is  allowed  to 
become  filled  with  succus,  which  is  secreted  on 
the  application  of  various  stimuli.  By  means  of 
Bernard's  gastric  cannula  (p.  3.S0)  inserted  into 
the  fistula  in  the  loop,  the  secretion  can  be 
removed  when  desired.] 


Fig.  146. 

Lieberkiihn's  Gland,   from  the 

large  intestine  of  a  dog. 


The  intestinal  juice  of  such  fistulse  flows  spontaneously  in  very 
small  amount,  and  is  increased  during  digestion;  it  is  increased — 
especially  its  mucus — by  mechanical,  chemical,  and  electrical  stimuli; 
at  the  same  time,  the  mucous  membrane  becomes  red,  so  that  100  □ 
centimetres  yields  13  to  18  grammes  of  this  juice  in  an  hour  (Thiry, 
Maslofi"). 

Characters. — The  juice  is  light  yellow,  opalescent,  thin,  strongly 
alkaline,  specific  gravity  1011,  evolves  CO^  when  an  acid  is  added; 
it  contains  albumin  and  ferments ;  mucin  occui's  in  the  juice  of  the 
large  intestine.  Its  composition  is — proteids  =  0'80  p.c;  other  organic 
substances  =  073  p.c;  salts,  0-88  p.c;  amongst  these — sodium  car- 
bonate, 0-32-0-34  p.c;  water,  97-59  p.c 

24! 


370  ACTIONS    OF   THE    INTESTINAL   JUICE. 

[The  intestinal  juice  obtained  by  Meade  Smith's  method  contained  only  0'39  per 
cent,  of  organic  matter,  and  in  this  respect  agreed  closely  with  the  juice  which  A. 
Moreau  procured  by  dividing  the  mesenteric  nerves  of  a  ligatured  loop  of  intestine.] 

[The  secretion  of  t)ie  large  intestine  is  much  more  viscid  than  that  of  the  small 
intestine.] 

Actions  of  succus  entericus. — The  digestive  functions  of  the  fluid  of 
the  small  intestine  are: — 

(1.)  It  has  less  diastatic  action  than  either  the  saliva  or  the 
pancreatic  juice  (Schiff,  Busch,  Quincke,  Garland),  but  it  does  not  form 
maltose;  while  the  juice  of  the  large  intestine  is  said  to  possess  this 
property  (Eichhorst).  V.  Wittich  extracted  the  ferment  with  a 
mixture  of  glycerine  and  water. 

[The  diastatic  action  of  the  small  intestine  is  incomparably  weaker  than  that  of 
the  saliva,  or  pancreatic  juice,  and  barely  exceeds  that  of  the  tissues  and  flviids  of 
the  bodies  generally.  A  similarly  weak  diastatic  action  is  possessed  by  the 
seci'etion  of  the  colon.] 

(2.)  It  converts  maltose  into  grape-sugar.  It  seems,  therefore,  to 
continue  the  diastatic  action  of  saliva  (§  148)  and  pancreatic  juice 
(§  170)  which  usually  form  only  maltose.  Thus  maltose  seems  to  be 
transformed  into  grape-sugar  by  the  intestinal  juice. 

(3.)  Fibrin  is  slowly  (by  the  trypsin  and  pepsin — Kiihne)  peptonised 
(Thiry,  Leube);  less  easily  albumin  (Masloff),  fresh  casein,  flesh  raw  or 
cooked,  vegetable  albumin  (KoUiker,  Schiff");  probably  gelatin  also  is 
changed  by  a  special  ferment  into  a  solution  which  does  not  gelatinise 
(Eichhorst). 

[The  ferment  for  this  purpose  is  mainly  contained  in  Brunner's  glands,  and  in 
Peyer's  patches  (Brown  and  Heron).] 

(4.)  Fats  are  only  partly  emulsionised  (Schiff"),  and  afterwards 
decomposed  (Vella). 

[M.  Hay  has  never  observed  any  emulsifying  action.  The  apparent  emulsification 
in  certain  instances  is  due  to  shaking  the  alkaline  juice  vidth  a  rancid  oil,  containing 
free  fatty  acids,  when  a  certain  quantity  of  a  soap  is  at  once  formed.] 

(5.)  According  to  CI.  Bernard,  invertin  occurs  in  intestinal  juice  (this 
ferment  can  also  be  extracted  from  yeast),  whereby  cane-sugar 
(C12H22O11)  takes  up  water  (  +  H2O)  and  becomes  converted  into  invert 
sugar,  which  is  a  mixture  of  left  rotating  sugar  (Isevulose,  C6H12O6) 
and  of  grape-sugar  (dextrose,  C6H12O6).  Heat  seems  to  be  absorbed 
during  the  process  (Leube).  (See  Carbohydrates  for  the  various  kinds 
of  sugar). 

[Hoppe-Seyler  has  suggested  that  this  ferment  is  not  a  natural  product  of  the 
body,  but  is  introduced  from  Avithout  with  the  food.  Matthew  Hay  has  recently 
disproved  this  theory  by,  amongst  other  reasons,  finding  it  to  be  invariably  present 
in  the  intestine  of  the  foetus.  It  is  found  in  every  portion  of  the  small  intestine, 
but  not  in  the  large  intestine,  nor  in  any  other  part  of  the  body,  and  is  much  less 
diffusible  than  diastase.] 


FERMENTATION   PROCESSES   IN    THE   INTESTINE.  371 

Fate  of  the  Ferments.— With  regard  to  the  digestive  ferments,  Langley  is 
of  opinion  that  they  are  destroyed  in  the  intestinal  canal ;  the  diastatic  ferment 
of  saliva  is  destroyed  by  the  HCl  of  the  gastric  juice;  pepsin  and  rennet  are  acted 
upon  by  the  alkaline  salts  of  the  pancreatic  and  intestinal  juices,  and  by  trjrpsin ; 
while  the  diastatic  and  peptic  ferments  of  the  pancreas  disappear  under  the 
influence  of  the  acid  fermentation  in  the  large  intestine. 

The  action  of  the  Nervous  System  on  the  secretion  of  the  intestinal  juice  is 
not  well  determined.  Section  or  stimulation  of  the  vagi  has  no  apparent  effect; 
while  extirpation  of  the  large  sympathetic  abdominal  ganglia  causes  the  intestinal 
canal  to  be  filled  witli  a  watery  fluid,  and  gives  rise  to  diarrhcea  (Budge).  This 
may  be  explained  by  the  paralysis  of  the  vaso-motor  nerves,  and  also  by  the 
section  of  large  lymphatic  vessels  during  the  operation,  whereby  absorption  is 
interfered  with  and  transudation  is  favoured. 

Moreau's  Experiment.— A  similar  result  is  caused  by  extirpation  of  the  nerves 
which  accompany  the  blood-vessels  going  to  a  loop  of  intestine  (Moreau).  [Moreau 
placed  four  ligatures  on  a  loop  of  intestine  at  equal  distances  from  each  other. 
The  ligatures  were  tied  so  that  three  loops  of  intestine  were  shut  ofl".  The  nerves 
to  the  middle  loojJ  were  divided,  and  the  intestine  was  replaced  in  the  abdominal 
cavity.  After  a  time,  a  very  small  amount  of  secretion,  or  none  at  all,  was  found 
in  two  of  the  ligatured  compartments  of  the  gut — i.  e. ,  in  those  with  the  nerves 
and  blood-vessels  intact — but  the  compartment  whose  nerves  had  been  divided 
contained  a  watery  secretion.] 

The  secretion  of  the  intestinal  and  gastric  juices  is  diminished  in  man  in  certain 
nervous  affections  (hysteria,  hypochondriasis,  and  various  cerebral  diseases) :  while 
in  other  conditions,  these  secretions  are  increased. 

If  an  isolated  intestinal  fistula  be  made,  and  various  drugs  administered, 
experiment  shows  that  the  mucous  membrane  excretes  iodine,  bromine,  lithium, 
sulphocyanides,  but  not  potassium  ferrocyanide,  arsenious  or  boracic  acid 
(Quincke),  or  iron  salts  (Glaevecke). 

In  sucl:lin(j><,  not  unfrequently  a  large  amount  of  acid  is  formed  when  the  fungi 
in  the  intestine  (Leabe)  split  up  milk-sugar  or  grape-sugar  into  lactic  acid.  Starch 
changed  into  grape-sugar  may  undergo  the  same  abnormal  process ;  hence,  infants 
ought  not  to  be  fed  Avith  starchy  food. 

184.  Fermentation  Processes  in  the  Intestine. 

Those  processes,  which  are  to  be  regarded  as  fermentations  or  putre- 
factive processes,  are  quite  different  from  those  caused  by  the  action  of 
distinct  ferments  (Frerichs,  Hoppe-Seyler).  The  putrefactive  changes 
are  connected  with  the  presence  of  lower  organisms,  so-called  fermenta- 
tion or  putrefaction  jiroducers  (Nencki) ;  and  they  may  develop  in 
suitable  media  outside  the  body.  The  lower  organisms  which  cause 
the  intestinal  fermentation  are  swallowed  with  the  food  and  the  drink, 
and  also  with  the  saliva.  When  they  are  introduced,  fermentation  and 
putrefaction  begin,  and  gases  are  evolved. 

Intestinal  Gases. — During  the  whole  of  the  foetal  period  until  birth, 
this  fermentation  cannot  occur ;  hence,  gases  are  never  present  in  the 
intestine  of  the  newly-born  (Breslau).  The  first  air-bubbles  pass  into 
the  intestine  with  the  saliva  which  is  swallowed,  even  before  food 
has  been  taken.     The  germs  of  organisms  are  thus  introduced  into  the 


372  I'UNGI   AS   EXCITERS   OE   fERMENfATION. 

intestinal  tract,  and  give  rise  to  the  formation  of  gases.  The  evohTtion 
of  intestinal  gases  goes  hand-in-hand  with  the  fermentations.  Atmo- 
spheric air  is  also  swallowed,  and  an  exchange  of  gases  takes  place  in 
the  intestine,  so  that  the  composition  of  the  intestinal  gases  depends 
upon  various  conditions. 

Kolbe  and  Euge  collected  the  gases  from  the  anus,  of  a  man,  and 
found  in  100  vols.: — 


Food. 

CO2. 

H. 

OH4. 

N. 

H2S. 

Milk,  .     .     . 
Flesh,  .     .     . 
Peas,   .     .     . 

16-8 
12-4 
21-0 

43-3 
21 
4-0 

0-9 

27-5 
55-9 

38-3 
57-8 
18-9 

Quantity  not 
estimated. 

With  regard  to  the  formation  of  gas  and  the  processes  of  fermenta- 
tion we  note — 

1.  Air  bubbles  are  swallowed  when  food  is  taken.  The  0  thereof 
is  rapidly  absorbed  by  the  walls  of  the  intestinal  tract,  so  that  in  the 
lower  part  of  the  large  intestine,  even  traces  of  0  are  absent.  In 
exchange,  the  blood-vessels  in  the  intestinal  wall  give  off  COg  into  the 
intestine,  so  that  a  part  of  the  COg  in  the  intestine  is  derived  by 
diffusion  from  the  blood. 

2.  H  and  CO2NH3  and  CH^  are  also  formed  from  the  intestinal 
contents  by  fermentation,  which  takes  place  even  in  the  small 
intestine  (Planer). 

Fungi  as  Exciters  of  Fermentation. — The  chief  agents  in  the  production 

of  fermentations,  putrefaction  and  other  similar  decompositions  are  undoubtedly  the 
group  of  the  fungi  called  Schizomycetes.  They  are  small  unicellular  organisms  of 
various  forms,  globular  (Micrococcus),  short  rods  (Bacterium),  long  rods  (Bacillus), 
or  spiral  threads  (Vibrio,  Spirillum,  Spirochceta).  The  mode  of  reproduction  is 
by  division,  and  they  may  either  remain  single  or  unite  to  form  colonies.  Each 
organism  is  usually  capable  of  some  degree  of  motion.  They  produce  profound 
chemical  changes  in  the  fluids  or  media  in  which  they  grow  and  multiply,  and  these 
changes  depend  upon  the  vital  activity  of  their  protoplasm.  These  minute  micro- 
scopic organisms  take  certain  constituents  from  the  "nutrient  fluids"  in  which 
they  live,  and  use  them  partly  for  building  up  their  own  tissues  and  partly  for  their 
own  metabolism.  In  these  processes,  some  of  the  substances  so  absorbed  and 
assimilated  undergo  chemical  changes,  some  ferments  seem  thereby  to  be  produced, 
which  in  their  turn  may  act  upon  material  present  in  the  nutritive  fluid. 

These  fungi  consist  of  a  capsule  or  envelope  enclosing  protoplasmic  contents. 
Many  of  them  are  provided  with  excessively  delicate  cilia,  by  means  of  which  they 
move  about.  The  new  organisms  produced  by  the  division  of  pre-existing  ones, 
sometimes  form  large  colonies  visible  to  the  naked  eye,  the  individual  fungi  being 
vmited  by  a  jelly-like  mass,  the  whole  constituting  zoogloea.  In  some  fungi,  repro- 
duction takes  place  by  spores;  more  especially  when  the  nutrient  fluids  are  poor 
in  nutritive  materials.  The  bacteria  form  longer  rods  or  threads  which  are  jointed, 
and  in  each  joint  or  segment  small  (I-2/u)  highly  refractive  globules  or  spores  are 
developed  (Fig.  148,  7).   In  some  cases,  as  in  the  butyric  acid  fermentation,  the  rods 


FERMENTATION  OF  THE  CARBOHYDRATES. 


373 


become  fusiform  before  spores  are  formed.  When  the  envelope  of  the  mother-cell 
is  ruptured  or  destroyed,  the  spores  are  liberated,  and  if  they  fall  upon  or  into  a 
suitable  medium,  they  germinate  and  reproduce  organisms  similar  to  those  from 
which  they  sprung.  The  process  of  spore- production  is  illustrated  in  Fig.  147,  7,  8, 
9,  and  in  1,  2,  3,  4  is  shown  the  process  of  germination  in  the  butyric  acid  fungus. 
The  spores  are  very  tenacious  of  life;  they  may  be  dried  when  they  resist  death  for 
a  very  long  time;  some  of  them  are  not  killed  by  being  boiled.  Some  fungi  exhibit 
their  vital  activities  only  in  the  presence  of  0  [Atrohes),  while  others  require  the 
exclusion  of  O  (Anai'rohes,  Pasteur).  According  to  the  products  of  their  action, 
they  are  classified  as  follows: — Those  that  produce  fermentations  (zymogenic 
schizomycetes);  those  that  produce  pigments  (chromogenic) ;  those  that  produce 
disagreeable  odours,  as  during  putrefaction  (bromogenic);  and  those  that  when 
introduced  into  the  living  tissues  of  other  organisms  T^roduce pathological  conditions, 
and  even  death  (pat Jiogenic).     All  these  diffei'ent  kinds  occur  in  the  human  body. 


(^ 


D 


3  %(p 

J 


Fig.  147. 

A,  Bacterium  acetl  in  the  form  of— cocci  (1);  diplococci  (2);  short  rods  (3),  and 
jointed  threads  (4,  5).  B,  Bacilbis  bufyricus—(l)  isolated  spores;  (2,  3,  4) 
germinating  condition  of  the  spores ;  (5,  6)  short  and  long  rods ;  (7,  8,  9) 
formation  of  spores  within  a  cellular  fitngus. 

When  we  consider  that  numerous  fungi  are  introduced  into  the  intestinal 
canal  with  the  food  and  drink — that  the  temperature  and  other  conditions  within 
this  tube  are  specially  favourable  for  their  development;  that  there  also  they  meet 
with  sufficient  pabulum  for  their  development  and  reproduction — we  cannot 
wonder  that  a  rich  crop  of  these  organisms  is  met  with  in  the  intestine,  and  that 
they  produce  these  numerous  decompositions. 

I.  Fermentation  of  the  Carho-hydrates. — (1.)  Bacterium  lacticum 
(Cohn),  (Ferment  lactique,  Pasteur)  are  biscuit-shaped  cells,  r5-3  fx  in 
lenoth,  arranged  in  groups  or  isolated.     They  split  up  sugar  into  lactic 

acid; 

1  grape-sugar  =  C6Hi206= 2  (CgHgOa)  =  2  milk-sugar. 

Milk-sugar  (C12H02O4)  may  be  split  up  by  the  same  ferment  causing  it 
to  take  up  HoO,  and  forming  2  molecules  of  grape-sugar,  2  (CeHi.^Og), 
which  are  again  split  into  4  molecules  of  lactic  acid,  4  (CjHgOg). 


374  FERMENTATION    OF   THE   FATS. 

The  funci  wliich  occur  everywhere  in  the  atmosphere  are  the  cause  of  the  spon- 
taneous acidification,  and  subsequent  coagulation  of  milk. — See  Milk. 

(2.)  Bacillus  butyricus  (B.  amylobacter,  Van  Tieghem ;  Clostridium 
butyricum,  Vibrion  butyrique,  Pasteur),  which  in  the  presence  of  starch 
is  often  coloured  blue  by  iodine,  changes  lactic  acid  into  butyric  acid, 
together  with  CO2  and  H  (Prazmowski). 

{C4H803=  1  butyric  acid. 
2  (C02)  =  2  carbonic  acid. 
4  H  =  4  hydrogen. 

This  fungus  (Fig.  147,  B)  is  a  true  anaerobe,  and  grows  only  in  the  absence  of  0. 
The  lactic  acid  fungus  uses  O  very  largely,  and  is,  therefore,  its  natural  precursor. 
The  butyric  acid  fermentation  is  the  last  change  undergone  by  many  carbo- 
hydrates, especially  of  starch  and  inulin.     It  takes  place  constantly  in  the  faeces. 

(3.)  A  fungus,  whose  nature  is  not  yet  determined,  causes  alcohol  to 
be  formed  from  carbohydrates  (Fitz),  The  presence  of  yeast  may 
cause  the  formation  of  alcohol  in  the  intestine,  and  in  both  cases  also 
from  milk-sugar,  which  first  becomes  changed  into  dextrose  (p.  298,  I). 

(4.)  Bacterium  aceti  (Fig.  147,  A)  converts  alcohol  into  acetic  acid  outside  the 
body.  Alcohol  (C2H60)  +  0  =  C2H40  (Aldehyd) -(- HgO.  Acetic  acid  (C2H4O2) 
is  formed  from  aldehyd  by  oxidation.  According  to  Nageli,  the  same  fungus  causes 
the  formation  of  a  small  amount  of  CO2  and  HgO.  As  the  acetic  fermentation  is 
arrested  at  35°C.,  this  fermentation  cannot  occur  in  the  intestine,  and  the  acetic 
acid,  which  is  constantly  found  in  the  feeces,  must  be  derived  from  a^nother  source. 
During  putrefaction  of  the  proteids  with  exclusion  of  air,  acetic  acid  is  produced 
(Nencki). 

(5.)  Starch  and  cellulose  are  partly  dissolved  by  the  schizomycetes  of 
the  intestine.  If  cellulose  be  mixed  with  cloacal-mucus  (Hoppe- 
Seyler),  or  with  the  contents  of  the  intestine  (Tappeiner),  n  molecules, 
[n  (CgHioOs)],  take  up  n  molecules  of  water,  +  n  (H2O),  and  produce 
three  times  n  molecules  CO2,  and  three  times  w  molecules  of  marsh- 
gas  3  n  (CH4). 

(6.)  Fungi,  whose  nature  is  unknown,  can  partly  transform  starch 
(?  and  cellulose)  into  sugar,  others  excrete  invertin — e.g.,  the  Leuko- 
nostoc  mesenteriodes,  which  develops  in  the  juice  of  turnips.  Invertin 
changes  cane-sugar  into  invert-sugar  (§  183,  II,  5). 

II.  Fermentation  of  the  Fats. — In  certain  putrefactive  conditions, 
organisms  of  an  unknown  nature  can  cause  neutral  fats  to  take 
up  water  and  split  into  glycerine  and  fatty  acids.  Glycerine — C3H5 
(H0)3 — is  a  triatomic  alcohol,  and  is  capable  of  undergoing  several 
fermentations,  according  to  the  fungus  which  acts  upon  it.  With  a. 
neutral  reaction,  in  addition  to  succinic  acid,  a  number  of  fatty  acids, 
H  and  CO2,  are  formed. 

Fitz  found  under  the  influence  of  the  hay-fungus  (Bacillus  subtilis,  Fig.  148) 
alcohol  with  caproic,  butyric,  and  acetic  acids ;  in  other  cases  butylic  alcohol  is 
the  chief  product. 


FERMENTATION    OF   THE    PROTEIDS.  375 

The  fatty  acids,  especially  as  chalk  soaps,  form  an  excellent  material 
for  fermentation.  Calcium  formiate  mixed  with  cloacal-mucus  fer- 
ments and  yields  calcium  carbonate,  CO2  and  H;  calcium  acetate, 
under  the  same  conditions,  produces  calcium  carbonate,  COg  and  CH4. 
Amongst  the  oxy-acids,  we  are  acquainted  with  the  fermentations  of 
lactic,  glycerinic,  malic,  tartaric,  and  citric  acids. 


0    ^   "i  J] 
1234 


Fig.  148. 

Bacillus  subtilis — 1,  spore ;  2,  3,  4,  germiuation  of  the  spores  ;  5,  6,  short  rods ; 
7,  jointed  thread,  with  the  formation  of  spores  in  each  segment  or  cell;  8, 
short  rods,  some  of  them  containing  spores ;  9,  spores  in  single  short  rods  j 
10,  fungus  with  a  cilium. 

According  to  Fitz,  lactic  acid  (in  combination  with  chalk),  produces  propionic 
and  acetic  acids,  CO2H2O.  Other  ferments  cause  the  formation  of  valerianic 
acid.  Glycerinic  acid,  in  addition  to  alcohol  and  succinic,  yields  chiefly  acetic  acid; 
malic  acid  forms  succinic  and  acetic  acid.  The  other  acids  above  enumerated 
yield  somewhat  similar  products. 

III.  Fermentation  of  the  Proteids. — There  do  not  seem  to  be 
fungi  of  sufficient  activity  in  the  intestine  to  act  upon  undigested 
proteids  and  their  derivatives.  Many  schizomycetes,  however,  can  pro- 
duce a  peptonising  ferment. 

We  have  already  seen  that  pancreatic  digestion  (p.  341),  acts  upon 
the  proteids,  forming,  among  other  products,  amido-acids,  leucin,  tyrosin, 
and  other  bodies.  Under  normal  conditions,  this  is  the  greatest  decom- 
position produced  by  the  pancreatic  juice.  The  putrefactive  fermentation 
of  the  large  intestine  (HiifFner,  Nencki)  causes  further  and  more  profound 
decompositions.  Leucin  (CgH^gNOa)  takes  up  two  molecules  of  water 
and  yields  valerianic  acid  (C^H^qO^),  ammonia,  COo  and  2(H2)- 
glycin  behaves  in  a  similar  manner.  Tyrosin  (CgHnNOg)  is  decom- 
posed into  indol  (CgH^N),  which  is  constantly  present  in  the  intes- 
tine (Kiihne),  CO2H2ON  (Nencki).  If  0  be  present,  other  decom- 
positions take  place.  These  putrefactive  products  are  absent  from 
the  intestinal  canal  of  the  foetus  and  the  newly-born  (Senator). 
During  the  putrefactive  decomposition  of  proteids,  CO2H2S,  also  H 
and  CH4,  are  formed;  the  same  result  is  obtained  by  boiling  them  with 


376  INDOL — SKATOL — PHENOL. 

alkalies.  Gelatin,  under  the  same  conditions,  yields  much  leucin  and 
ammonia,  COo,  acetic,  butyric,  and  valerianic  acids,  and  glycin  (ISTencki). 
Mucin  and  nuclein  undergo  no  change.  Artificial  pancreatic  digestion 
experiments  rapidly  tend  to  undergo  putrefaction. 

The  substance  which  causes  the  peculiar  f seal  odour  is  produced  by  putrefaction, 
but  its  nature  is  not  known.  It  clings  so  firmly  to  indol  and  skatol  that  these  sub- 
stances were  formerly  regarded  as  the  odorous  bodies,  but  when  they  are  prepared 
pure  they  are  odourless  (Bayer).  The  above-mentioned  putrefactive  processes, 
which  also  occur  in  pancreas  undergoing  decomposition,  may  be  interrupted  by 
antiseptics  (salicylic  acid).  The  putrefactive  products  of  the  pancreas  give  a  red 
colour  or  precipitate  with  chlorine  water. 

Indol. — Amongst  the  solid  substances  in  the  large  intestine  formed 
07ily  hj  putref action  is  indol  (CgHyN),  a  substance  which  is  also  formed 
when  proteids  are  heated  with  alkalies,  or  by  overheating  them  with 
water  to  200°C.  It  is  the  stage  preceding  the  indican  in  the  urine. 
If  the  products  of  the  digestion  of  the  proteids — the  peptones — are 
rapidly  absorbed,  there  is  only  a  slight  formation  of  indol ;  but  when 
absorption  is  slight,  and  putrefaction  of  the  products  of  pancreatic 
digestion  occurs,  much  indol  is  formed,  and  indican  appears  in  the 
urine. 

Jaff^  found  much  indican  in  the  urine  in  strangulated  hernia,  and  when  the 
small  intestine  was  obstructed.  Landois  observed  the  same  after  the  transfusion 
of  heterogeneous  blood. 

A.  Bayer  prepared  indigo-blue  artificially  from  ortho-phenyl-propionic  acid,  by 
boiling  it  with  dilute  caustic  soda,  after  the  addition  of  a  little  grape-sugar.  He 
obtained  indol  and  skatol  from  indigo-blue.  Hoppe-Seyler  found  that  on  feeding 
rabbits  with  ortho-nitrophenyl-proprionic  acid,  much  indican  was  present  in  the 
urine. 

Phenol  (CgHgO)  is  formed  by  putrefaction  in  the  intestine,  and  it 
is  also  formed  when  fibrin  and  pancreatic  juice  putrefy  outside  the 
body  (Baumann),  while  Brieger  found  it  constantly  in  the  fseces.  It 
seems  to  be  increased  by  the  same  circumstances  that  increase  indol 
(Salkowski),  as  an  excess  of  indican  in  the  urine  is  accompanied  by 
an  increase  of  phenylsulphuric  acid  in  that  fluid. 

Hydrocinnamic  acid  (phenylpropionic  acid)  may  also  be  obtained  from  putre- 
fying flesh  and  fibrin.  It  is  completely  oxidised  in  the  body  into  benzoic  acid,  and 
appears  as  hippuric  acid  in  the  urine.  Thus  is  explained  the  formation  of  hippuric 
acid  from  a  purely  albuminous  diet  (E.  and  H.  Salkowski). 

Skatol  (C9H9N  =  methylindol) — (Brieger),  is  a  constant  human 
faecal  substance,  and  has  been  prepared  artificially  by  Nencki  and 
Secretan  from  egg-albumin,  by  allowing  it  to  putrefy  for  a  long  time 
under  water.  It  also  appears  in  the  urine  as  a  sulphuric  acid  com- 
pound. The  excretin  of  human  faeces,  described  by  Marcet,  is  related 
to  cholesterin,  but  its  history  and  constitution  are  unknown. 


TROCESSES   IN    THE   LARGE   INTESTINE.  377 

It  is  of  the  utmost  importance,  in  connection  with  the  processes  of 
putrefaction,  to  determine  whether  they  take  place  when  oxygen  is 
excluded  or  not  (Pasteur).  When  0  is  absent,  reductions  take  place ; 
oxy-acids  are  reduced  to  fatty  acids,  and  HCH4  and  HgS  are  formed; 
while  the  H  may  produce  further  reductions.  If  0  be  present,  the 
nascent  H  separates  the  molecule  of  free  ordinary  oxygen  {  =  0^  into 
two  atoms  of  active  oxygen  ( =  0).  Water  is  formed  on  the  one  hand, 
while  the  second  atom  of  0  is  a  powerful  oxidizing  agent  (Hoppe- 
Seyler). 

[It  is  not  improbable  that  some  substances,  as  sulphur,  are  in  part  rendered 
soluble  and  absorbed  by  the  action  of  the  nascent  hydrogen  evolved  by  the 
schizomycetes,  forming  a  soluble  hydrogen  compound  with  the  substance  (Matthew- 
Hay).] 

It  is  remarkable  that  the  putrefactive  processes,  after  the  development  of 
phenol,  indol,  skatol,  cresol,  phenylpropionic  and  phenylacetic  acids,  are  after- 
wards limited,  and  after  a  certain  concentration  is  reached  they  cease  altogether. 
The  putrefactive  process  produces  antiseptic  substances  which  kill  the  micro- 
organisms (Wernich),  so  that  we  may  assume,  that  these  substances  limit  to  a 
certain  extent  the  putrefactive  processes  in  the  intestine. 

The  reaction  of  the  intestine  immediately  below  the  stomach  is  acid, 
but  the  pancreatic  and  intestinal  juices  cause  a  neutral  and  afterwards 
an  alkaline  reaction,  which  obtains  along  the  whole  small  intestine. 
In  the  large  intestine,  the  reaction  is  generally  acid,  on  account  of  the 
acid  fermentation  and  the  decomposition  of  the  ingesta  and  the  fseces. 

185.  Processes  in  the  Large  Intestine. 

Within  the  large'  intestine,  the  fermentative  and  putrefactive  pro- 
cesses are  certainly  more  prominent  than  the  digestive  processes  proper, 
as  only  a  very  small  amount  of  the  intestinal  juice  is  found  in  it 
(Kiihne).  The  absorptive  function  of  the  large  intestine  is  greater  than 
its  secretory  function,  as  at  the  beginning  of  the  colon,  its  contents  are 
thin  and  watery,  but  in  the  further  course  of  the  intestine  they  become 
more  solid.  Water  and  the  products  of  digestion  in  solution  are  not 
the  only  substances  absorbed,  but  under  certain  circumstances,  un- 
changed fluid  egg-albumin  (Voit  and  Bauer,  Czerny  and  Latschen- 
berger),  milk  and  its  proteids  (Eichhorst),  flesh- juice,  solution  of 
gelatin,  myosin  with  common  salt,  may  also  be  absorbed.  Experi- 
ments with  acid-albumin,  syntonin,  or  blood-serum  gave  no  result. 
Toxic  substances  are  absorbed  more  rapidly  than  from  the  stomach 
(Savory).  The  fsecal  matters  are  formed  or  rather  shaped  in  the  lower 
part  of  the  gut.  The  csecum  of  many  animals,  e.g.,  rabbit,  is  of  con- 
siderable size,  and  in  it  fermentation  seems  to  occur  with  considerable 
energy,  giving  rise  to  an  acid  reaction.     In  man,  the  chief  function  of 


378  CHARACTERS    OF   THE   F^.CES. 

the  caecum  is  absorption,  as  is  shown  by  the  great  number  of  lymphatics 
in  its  walls.  From  the  lower  part  of  the  small  intestine  and  the  caecum 
onwards,  the  ingesta  assume  the  faecal  odour. 

The  amount  of  faeces  is  about  170  grms.  (60-250  grms.)  in  24 
hours ;  but  if  much  indigestible  food  be  taken,  it  may  be  as  much  as 
500  grms.  The  amount  is  less,  and  the  absolute  amount  of  solids  is 
less,  after  a  diet  of  flesh  and  albumin,  than  after  a  vegetable  diet.  The 
faeces  are  rendered  lighter  by  the  evolution  of  gases,  and  hence  they 
float  on  water. 

The  consistence  of  the  fasces  depends  on  the  amount  of  water  pre- 
sent— it  is  usually  about  75  per  cent.  The  amount  of  water  depends 
partly  on  the  food — pure  flesh  diet  causes  relatively  dry  faeces,  while 
substances  rich  in  sugar  yield  faeces  with  a  relatively  large  amount  of 
water.  The  quantity  of  Avater  taken  has  no  efi'ect  upon  the  amount  of 
water  in  the  faeces.  But  the  energy  of  the  peristalsis  has  this  effect, 
that  the  more  energetic  it  is,  the  more  watery  the  faeces  are,  because 
sufficient  time  is  not  allowed  for  absorption  of  the  fluid  from  the 
ingesta.  Paralysis  of  the  blood-  and  lymph-vessels,  after  section  of  the 
nerves,  leads  to  a  watery  condition  of  the  faeces  (p.  371). 

The  reaction  is  often  acid  in  consequence  of  lactic  acid  being 
developed  from  the  carbo-hydrates  of  the  food.  Numerous  other  acids 
produced  by  putrefaction  are  also  present  (§  184).  If  much  ammonia 
be  formed  in  the  lower  part  of  the  intestine,  a  neutral  or  even  alkaline, 
reaction  may  obtain.  A  copious  secretion  of  mucus  favours  the 
occurrence  of  a  neutral  reaction. 

The  odour,  which  is  stronger  after  a  flesh  diet  than  after  a  vegetable 
diet,  is  caused  by  some  faecal  products  of  putrefaction,  which  have  not 
yet  been  isolated;  also  by  volatUe  fatty  acids  and  by  sulphuretted 
hydrogen,  when  it  is  j)resent. 

The  colour  of  the  faeces  depends  upon  the  amount  of  altered  bile- 
pigments  mixed  Avith  them,  whereby  a  bright  yellow  to  a  dark-brown 
colour  is  obtained. 

The  coloiir  of  the  food  is  also  of  importance.  If  much  blood  be  present  in  the 
food,  the  fseces  are  ahnost  brownish-black  from  htematin  ;  green  vegetables  = 
brownish  green  from  chlorophyll ;  bones  (dog)  =  white  from  the  amount  of  lime  ; 
preparations  of  iron  =  black  from  the  formation  of  sulphide  of  iron.  [The 
pigment  of  claret  tinges  the  faeces.] 

The  fseces  contain — 

(1.)  The  unchanged  residue  of  animal  or  vegetable  tissues  used  as 
food ;  hairs,  horny  and  elastic  tissues ;  most  of  the  cellulose,  woody 
fibres,  spiral  vessels  of  vegetable  cells,  giun. 

(2.)  Portions  of  digestible  substances,  especially  when  these  have 
been  taken  in  too  large  amount,  or  when  they  have  not  been  sufficiently 


COMPOSITION    OF   THE    l-VECES.  379 

broken  up    by   chewing.     Portions  of  muscular  fibres,  ham,    tendon, 

cartilage,  particles  of  fat,  coagulated  albumin — vegetable    cells   from 

potatoes  and  vegetables,  raw  starch,  &c. 

All  food  yields  a  certain  amount  of  residue — white  bread,  3'7  p.c. ;  rice,  4*1  p.c. ; 
flesh,  4"7  p.c;  potatoes,  9"4p.c.;  cabbage,  14*9  p.c;  black  bread,  15  p.c;  yellow 
turuij),  20 '7  p.c.  (Rubner). 

(3.)  The  decomposition  products  of  the  bile-pigments,  which  do  not 
now  give  the  Gmelin-Heintz  reaction ;  as  well  as  the  altered  bile-acids 
(§177,  2).  This  reaction,  however,  may  be  obtained  in  pathological 
stools,  especially  in  those  of  a  green  colour ;  unaltered  bilirubin,  bili- 
verdin,  glycocholic,  and  taurocholic  acids  occur  in  meconium  (Zweifel, 
Hoppe-Seyler). 

(4.)  Unchanged  mucin  and  nuclein — the  latter  occasionally  after  a 
diet  of  bread,  together  with  cylindrical  epithelium  in  a  state  of  partial 
solution,  from  the  intestinal  canal,  and  occasional  drops  of  oil. 
Cholesterin  is  very  rare.  The  less  the  mucus  is  mixed  with  the  faeces, 
the  lower  the  part  of  the  intestine  from  which  it  was  derived 
(Xothnagel). 

(5.)  After  a  milk  diet  and  also  after  a  fatty  diet,  crystalhne  needles 
of  lime,  combined  with  fatty  acids,  chalk-soaps,  constantly  occur,  even 
in  sucklings  (Wegscheider).  Even  unchanged  masses  of  casein  and 
fat  occur  during  the  milk-cure.  Compounds  of  ammonia,  with  the 
acids  mentioned  at  p.  375,  the  residt  of  putrefaction,  belong  to  the 
faecal  matters  (Brieger). 

(6.)  Amongst  inorganic  residues,  soluble  salts  rarely  occur  in  the 
faeces  because  they  diffuse  readily — e.g.,  common  salt,  and  the  other 
alkaline  chlorides,  the  compounds  of  phosphoric  acid,  and  some  of  those 
of  sulphuric  acid.  The  insoluble  compounds,  of  which  ammoniaco- 
magnesic  or  triple  phosphate,  neutral  calcic  phosphate,  yellow  coloured 
lime  salts,  calcium  carbonate,  and  magnesium  phosphate  are  the  chief, 
form  70  p.c.  of  the  ash.  Some  of  these  insoluble  substances  are  derived 
from  the  food,  as  lime  from  bones,  and  in  part  they  are  excreted  after 
the  food  has  been  digested,  as  ashes  are  eliminated  from  food  which 
has  been  burned. 

The  excretion  of  inorganic  substances  is  sometimes  so  great,  that 
they  form  incrustations  around  other  fsecal  matters.  Usually 
ammoniaco-magnesic  phosphate  occurs  in  large  crystals  by  itself,  or  it 
may  be  mixed  with  magnesium  phosphate. 

(7.)  A  considerable  portion  of  normal  fsecal  matter  consists  of 
micrococci  and  microbacteria  (Bacterium  termo — Woodward,  Noth- 
nagel).  Bacillus  subtilis  is  not  very  plentiful,  while  yeast  is  seldom 
absent  (Frerichs,  Nothnagel).  In  stools  that  contain  much  starch,  the 
bacillus  amylobacter,  which  is  tinged  blue  with  iodine,  occurs  (p.  374), 


380  PATHOLOGICAL   VARIATIONS   OF   DIGESTION. 

and  other  small  globular  or  rod-like  fungi,  which  give  a  similar  reaction 
(Nothnagel,  Uffelmann).  Bienstock,  who  has  devoted  attention  to  the 
microbes  of  the  fseces,  finds  two  kinds  of  bacteria  in  all  fseces ;  both 
resemble  B.  subtilis  (Fig.  148)  very  closely,  but  they  are  distinguished 
from  it  by  their  mode  of  development.  They  do  not  cause  any 
fermentative  action.  There  are  several  other  forms  found  in  the  fgecal 
evacuations,  under  different  circumstances. 

The  changes  of  the  intestinal  contents  have  been  studied  on  persons  with  an 
accidental  intestinal  fistula,  or  an  artificial  anus. 

186.  Pathological  Variations. 

A.  The  taking  of  food  may  be  interfered  with  by  spasm  of  the  muscles  of 
mastication  (usually  accompanied  by  general  spasms),  stricture  of  the  oeso- 
phagus, by  cicatrices  after  swallowing  caustic  fluids  {e.g.,  caustic  potash,  mineral 
acids),  or  by  the  presence  of  a  tumour,  such  as  cancer.  Inflammation  of  all  kinds 
in  the  mouth  or  pharynx  interferes  with  the  taking  of  food.  Impossibility  of 
swallowing  occurs  as  part  of  the  general  phenomena  in  disease  of  the  medulla 
oblongata,  in  consequence  of  paralysis  of  the  motor  centre  (superior  olives)  for  the 
facial,  vagus,  and  hypoglossal  nerves,  and  also  for  the  aff'erent  or  sensory  fibres  of 
the  gloss-pharyngeal,  vagus,  and  trigeminus.  Stimulation  or  abnormal  excitation 
of  these  parts  causes  spasmodic  swallowing,  and  the  disagreeable  feeling  of  a 
constriction  in  the  neck  (globus  hystericus). 

B.  The  secretion  of  saliva  is  diminished  during  inflammation  of  the  salivary 
glands;  occlusion  of  their  ducts  by  concretions  (salivary  calculi);  also  by  the  use  of 
atropin,  daturin,  and  during  fever,  whereby  the  secretory  (not  the  vaso-motor) 
fibres  of  the  chorda  appear  to  be  paralysed  (p.  287).  When  the  fever  is  very  high,  no 
saliva  is  secreted.  The  saliva  secreted  during  moderate  fever  is  turbid  and  thick, 
and  usually  acid.  As  the  fever  increases,  the  diastatic  action  of  the  saliva 
diminishes  (Ufl'elmann).  The  secretion  is  increased,  by  stimulation  of  the  buccal 
nerves  (inflammation,  ulceration,  trigeminal  neuralgia),  so  that  the  saliva  is 
secreted  in  great  quantity.  Mercury  and  jaborandi  cause  secretion  of  saliva,  the 
former  causing  stomatitis,  which  excites  the  secretion  of  saliva  reflexly.  Even 
diseases  of  the  stomach  accompanied  by  vomiting,  cause  secretion  of  saliva.  A 
very  thick  tenacious  sjnnpathetic  saliva  occurs  when  there  is  violent  stimulation 
of  the  vascular  system  during  sexual  excitement,  and  also  during  certain  psychical 
conditions.  The  reaction  of  the  saliva  is  acid  in  catarrh  of  the  mouth,  in  fever 
in  consequence  of  decomposition  of  the  buccal  epithelium,  and  in  diabetes  mellitus 
in  consequence  of  acid  fermentation  of  the  saliva  which  contains  sugar.  Hence, 
diabetic  persons  often  suffer  from  carious  teeth.  Unless  the  mouth  of  an  infant 
be  kept  scrupulously  clean,  the  saliva  is  apt  to  become  acid. 

C.  Disturbances  in  the  activity  of  the  mUSCUlature  of  the  Stomach  may  be  due 
to  paralysis  of  the  muscxilar  layers,  whereby  the  stomach  becomes  distended,  and 
the  ingesta  remain  a  long  time  in  it.  A  special  form  of  paralysis  of  the  stomach  is 
due  to  non-closure  of  the  pylorus  (Ebstein).  This  may  be  due  to  disturbances  of 
innervation  of  a  central  or  peripheral  nature,  or  there  may  be  actual  paralysis  of 
the  pyloric  sphincter,  or  ansesthesia  of  the  pyloric  mucous  membrane,  which  acts 
reflexly  upon  the  sphincter  muscle ;  and  lastly,  it  may  be  due  to  the  reflex 
impulse  not  being  transferred  to  the  efi"erent  fibre  within  the  nerve  centre. 
Abnormal  activity  of  the  gastric  musculature  hastens  the  passage  of  the  ingesta 
into  the  intestine ;  vomiting  often  occurs. 


DIGESTION   DURING  FEVER  AND  ANAEMIA.  38 1 

Gastric  digestion  is  delayed  by  violent  bodily  or  mental  exercise,  and  some- 
times it  is  arrested  altogether.  Sudden  mental  excitement  may  have  the  same 
effect.  These  effects  are  very  probably  caused  through  the  vaso-motor  nerves  of 
the  stomach.  Feeble  and  imperfect  digestion  may  be  of  a  purely  nervous  nature 
(Dyspepsia  nervosa— Leube  ;  Neurasthenia  gastrica — Burkart).  [According  to 
J.  W.  Fraser,  all  infused  beverages,  tea,  coffee,  cocoa,  retard  the  peptic  digestion 
of  proteids,  with  few  exceptions.  The  retarding  action  is  less  with  coffee  than 
with  tea.  The  tannic  acid  and  volatile  oil  seem  to  be  the  retarding  ingredients  in 
teas.] 

Inflammatory  or  catarrhal  afi"ections  of  the  stomach,  as  well  as  ulceration 

and  new  formations,  interfere  with  digestion,  and  the  same  result  is  caused  by 
eating  too  much  food  which  is  difficult  of  digestion,  or  taking  too  much  highly 
spiced  sauces  or  alcohol.  In  the  case  of  a  dog  suffering  from  chronic  gastric  catarrh, 
Griitzner  observed  that  the  secretion  took  place  continuously,  and  that  the  gastric 
juice  contained  little  pepsin,  was  turbid,  sticky,  feebly  acid,  and  even  alkaline. 
The  introduction  of  food  did  not  alter  the  secretion,  so  that  in  this  condition  the 
stomach  really  obtains  no  rest.  The  chief  cells  of  the  gastric  glands  were  turbid. 
Hence,  in  gastric  catarrh,  we  ought  to  eat  frequently,  but  take  little  at  a  time, 
while  at  the  same  time  dilute  (O'-ip.c.)  hydrochloric  acid  ought  to  be  adminis- 
tered. Small  doses  of  common  salt  seem  to  aid  digestion.  [In  cases  of  carcinoma 
of  the  stomach,  the  acid  reaction  of  the  gastric  juice  is  almost  invariably  absent.] 

Feeble  digestion  may  be  caused  either  by  imperfect  formation  of  acid  or 
pepsin,  so  that  both  substances  may  be  administered  in  such  a  condition.  [It 
may  also  be  due  to  deficient  muscular  power  in  the  wall  of  the  stomach.]  In 
other  cases,  lactic,  butyi'ic,  and  acetic  acids  are  formed,  owing  to  the  presence  of 
lowly  organisms.  In  such  cases,  small  doses  of  salicylic  acid  are  useful  (Hoppe- 
Seyler),  together  with  some  hydrochloric  acid.  Pepsin  need  not  be  given  often, 
as  it  is  rarely  absent,  even  from  the  diseased  gastric  mucous  membrane.  Albumin 
has  been  found  in  the  gastric  juice  in  cases  of  gastric  catarrh  and  cholera. 

D.  Digestion  dnring  Fever  and  Anaemia.— Beaumont  found  that  in  the 

case  of  Alexis  St.  Martin,  when  fever  occurred,  a  small  amount  of  gastric  juice 
was  secreted  ;  the  mucous  membrane  was  dry,  red,  and  irritable.  Dogs  suffering 
from  septicasmic  fever,  or  rendered  anemic  by  great  loss  of  blood,  secrete  gastric  juice 
of  feeble  digestive  power  and  containing  little  acid  (Manassein).  Hoppe-Seyler 
investigated  the  gastric  juice  of  a  typhus  patient,  in  which  Von  der  Velden  found 
no  free  acid,  and  he  found  the  same  in  gastric  catarrh,  fever,  and  in  cancer  of  the 
stomach.  The  gastric  juice  of  the  tj^phus  patient  did  not  digest  artificially,  even 
after  the  addition  of  hydrochloric  acid.  The  diminution  of  acid,  under  these  cir- 
cumstances, favours  the  occm-rence  of  a  neutral  reaction,  so  that,  on  the  one  hand, 
digestion  cannot  proceed,  and,  on  the  other,  fermentative  processes  (lactic  and 
butyric  acid  fermentations  with  the  evolution  of  gases)  occur.  These  results  are 
associated  with  the  presence  of  micro-organisms  and  Sarcina  ventricidl  (Goodsir). 
He  ad%T.ses  the  administration  of  hydrochloric  acid  and  pepsin,  and  when  there 
are  symptoms  of  fermentation,  small  doses  of  salicylic  acid.  Uffelmann  found  the 
secretion  of  a  peptone-forming  gastric  juice  ceased  in  fever,  when  the  fever  is 
severe  at  the  outset,  when  a  feeble  condition  occiu's,  or  when  the  temperature  is 
very  high.  The  amount  of  juice  secreted  is  certainly  diminished  during  fever. 
The  excitability  of  the  mucous  membrane  is  increased,  so  that  vomiting  readily 
occurs.  The  increased  excitability  of  the  vaso-motor  nerves  during  fever  (Heiden- 
hain)  is  disadvantageous  for  the  secretion  of  the  digestive  fluids.  Beaumont 
observed  that  fluids  are  rapidly  absorbed  jfrom  the  stomach  during  fever,  but  the 
absorption  of  peptones  is  diminished  on  account  of  the  accompanying  catarrhal 
condition  of  the  stomach,  and  the  altered  functional  activity  of  the  muscularia 
mucosa  (Leube). 
Many  salts  when  given  in  large  amount  disturb  gastric  digestion — e.g.,  the 


382  CONSTIPATION   AND    DIARRHCEA. 

sulphates.  While  the  alkaloids,  morphia,  strychnia,  digitalin,  narcotin,  veratria 
have  a  similar  action  ;  quinine  favours  it  (Wolberg).  In  some  nervous  individuals 
a  "  peristaltic  un-rest  of  the  stomach,"  conjoined  with  a  dyspeptic  condition,  occurs 
(Kussmaul). 

E.  In  acute  diseases,  the  secretion  of  bile  is  affected  ;  it  becomes  less  in  amount 
and  more  watery,  i.e.,  it  contains  less  specific  constituents.  If  the  liver  undergoes 
great  structural  change,  the  secretion  may  be  arrested. 

F.  Gallstones- — When  decomposition  of  the  bile  occurs,  gallstones  are  formed 
in  the  gaU-hladder  or  in  the  bile-ducts.  Some  are  white,  and  consist  almost  entirely 
of  stratified  layers  of  crystals  of  cholesterin.  The  brown  forms  consist  of  bilirubin- 
lime  and  calcium  carbonate,  often  mixed  with  iron,  copper,  and  manganese.  The 
gallstones  in  the  gall-bladder  become  facetted  by  rubbing  against  each  other.  The 
nucleus  of  the  white  stones  often  consists  of  chalk  and  bile  colouring  matters, 
together  with  nitrogenous  residues,  derived  from  shed  epithelium,  mucin,  bile  salts 
and  fats.  Gallstones  may  occlude  the  bile-duct  and  cause  cholaemia.  When  a 
small  stone  becomes  impacted  in  a  duct,  it  gives  rise  to  excessive  pain  constituting 
hepatic  colic,  and  may  even  cause  rupture  of  the  bile-duct  with  its  sharp  edges. 

G.  Nothing  certain  has  been  determined  regarding  the  pancreatic  secretion 
in  disease,  but  in  fever,  it  appears  to  be  diminished  in  amount  and  digestive 
activity.  The  suppression  of  the  pancreatic  secretion  [as  by  a  cancerous  tumour 
of  the  head  of  the  pancreas]  is  often  accompanied  by  the  appearance  of  fat  in  the 
form  of  globules  or  groups  of  crystals  in  the  fseces. 

H.  Constipation  is  a  most  important  derangement  of  the  digestive  tract.  It 
may  be  caused  by — 1.  Conditions  which  obstruct  the  normal  chaniiel,  e.g.,  con- 
striction of  the  gut  from  stricture — in  the  large  gut  after  dysentery,  tumours, 
rotation  on  its  axis  of  a  loop  of  intestine  (volvulus),  or  invagination,  occlusion 
of  a  coil  of  gut  in  a  hernial  sac,  or  by  the  pressure  of  tumours  or  exudations 
from  without,  or  congenital  absence  of  the  anus.  2.  Too  great  dryness  of 
the  contents,  caused  by  too  little  water  in  the  articles  of  diet,  diminution 
of  the  amount  of  the  digestive  secretions,  e.g.,  of  bile  in  icterus;  or  in 
consequence  of  much  fluid  being  given  off  by  other  organs,  as  after  copious 
secretion  of  saliva,  milk,  or  in  fever.  3.  Variations  in  the  functional  activity  of 
the  muscles  and  motor-nervous  apparatus  of  the  gut  may  cause  constipation,  owing 
to  imperfect  peristalsis.  This  condition  occurs  in  inflammations,  degenerations, 
chronic  catarrh,  diaphragmatic  inflammation.  Affections  of  the  spinal  cord,  and 
sometimes  also  of  the  brain,  are  usually  accompanied  bj'  slow  evacuation  of  the 
intestine.  Whether  diminished  mental  activity  and  hypochondrias  are  the  cause 
of  or  are  caused  by  constipation  is  not  proved.  Spasmodic  contraction  of  a  part  of 
the  intestine  may  cause  temporary  retention  of  the  intestinal  contents,  and,  at  the 
same  time,  give  rise  to  great  pain  or  colic ;  the  same  is  true  of  spasm  of  the  anal 
sphincter,  which  may  be  excited  reflexly  from  the  lower  part  of  the  gut.  The 
fsecal  masses  in  constipation  are  usually  hard  and  dry,  owing  to  the  water  being 
absorbed ;  hence  they  form  large  masses  or  scyhala  within  the  large  intestine,  and 
these  again  give  rise  to  new  resistance. 

Amongst  the  reagents  which  prevent  evacuation  of  the  bowels,  some  paralyse  the 
motor  apparatus  temporarily,  e.g.,  opium,  morphia;  some  diminish  the  secretion  of 
the  intestinal  mucous  membrane,  and  cause  constriction  of  the  blood-vessels,  as 
tannic  acid,  vegetal)les  containing  tannin,  alum,  chalk,  lead  acetate,  silver  nitrate, 
bismuth  nitrate. 

I.  Increased  evacuation  of  the  intestinal  contents  is  usually  accompanied  by  a 
watery  condition  of  tlie  fteces,  constituting  diarrhoea- 

The  causes  are  : — 

1.  A  too  rapid  movement  of  the  contents  through  the  intestine,  chiefly  through 
the  large  intestine,  so  that  there  is  not  time  for  the  normal  amount  of  absorption 
to  take  place.     The  increased  peristalsis  depends  upon  stimulation  of  the  motor- 


COMPARATIVE   PHYSIOLOGY   OF   DIGESTION.  383 

nervous  apparatus  of  the  intestine,  usually  of  a,  reflex  nature.  Rapid  transit  of  the 
contents  through  the  intestine  causes  the  evacuation  of  certain  substances,  which 
cannot  be  digested  in  so  short  a  time. 

2.  The  stools  become  thinner  from  the  presence  of  much  water,  mucus,  and  the 
admixture  Avith  fat,  and  by  eating  fruit  and  vegetables.  In  rare  cases,  when  the 
evacuations  contain  much  mucin,  Charcot's  crystals  (Fig.  115,  c)  occur.  In  ulcera- 
tion of  the  intestine,  leucocytes  (pus)  are  present  ^Nothnagel). 

3.  Diarrhoea  may  occur  as  a  consequence  of  disturbance  of  the  diffusion-processes 
through  the  iutestinal  walls,  as  in  affections  of  the  epithelium,  when  it  becomes 
swollen  in  inflammatory  or  catarrhal  conditions  of  the  intestinal  mucous  membrane. 
[Irritation  over  the  abdomen,  as  from  the  subcutaneous  injection  of  small  quan- 
tities of  saline  solutions,  causes  diarrhoea  (M.  Hay).] 

4.  It  may  also  be  due  to  increased  secretion  into  the  intestine,  as  in  capillary 
diffusion,  when  magnesium  sulphate  in  the  intestine  attracts  water  from  the 
blood. 

The  same  occurs  in  cholera,  when  the  stools  are  copious  and  of  a  rice-water 
character,  and  are  loaded  with  epithelial  cells  fi'om  the  villi.  The  transudation 
into  the  intestine  is  so  great  that  the  blood  in  the  arteries  becomes  very  thick, 
and  may  even  on  this  account  cease  to  circulate. 

Transudation  into  the  intestine  also  takes  place  as  a  consequence  of  paralysis  of 
the  vaso-motor  nerves  of  the  intestine.  This  is  perhaps  the  case  in  diarrhcea 
following  upon  a  cold.  Certain  substances  seem  directly  to  excite  the  secretory 
organs  of  the  intestines  or  their  nerves,  such  as  the  drastic  purgatives  (p.  :j()4). 
Pilocarpin  injected  into  the  blood  causes  great  secretion  (Masloff). 

During  febrile  conditions,  the  secretion  of  the  mtestinal  glands  seems  to  be 
altered  quantitatively  and  qualitatively,  with  simultaneous  alteration  of  the 
functional  activity  of  the  musculature  and  the  organs  of  a1)sorption,  while  the 
excitability  of  the  mucous  membrane  is  increased  (Utfehnann).  It  is  important  to 
note  that  in  many  acute  febrile  diseases,  the  amount  of  ommon  salt  in  the  urine 
diminishes,  and  increases  again  as  the  fever  subsides. 

187.  Comparative. 

Salivary  Glands. — Amongst  Mammals  the  herbivora  have  larger  salivaiy 
glands  than  the  caruivora ;  while  midway  between  both  are  the  omnivora.  The 
whale  has  no  salivary  glands.  The  pinnipedia  have  a  small  parotid,  which  is 
absent  in  the  echidna.  The  dog  and  many  carnivora  have  a  special  gland  lying 
in  the  orbit,  the  orbital  or  zygomatic  gland.  In  Birds  the  salivary  glands  open  at 
the  angle  of  the  mouth,  in  them  the  parotid  is  absent.  Amongst  Reptiles  the 
parotid  of  some  species  is  so  changed  as  to  form  poison  glands ;  the  tortoise  has 
sublingual  glands  ;  reptiles  have  labial  glands.  The  Amphibia  and  FisheS  have 
merely  small  glands  scattered  over  the  mouth.  The  salivary  glands  are  large  in 
Insects  ;  some  of  them  secrete  formic  acid.  The  salivary  glands  are  well  de- 
veloped in  molluscs,  and  the  saliva  of  dolium  galea  contains  more  than  3  p.c.  of 
free  sulphuric  acid  (?)     The  cephalopods  have  double  glands. 

A  Crop  is  not  present  m  any  mammal ;  the  stomach  is  either  simple,  as  in  man, 
or,  as  in  many  rodents,  it  is  divided  into  two  halves,  into  a  cardiac  and  a  pyloric 
portion.  The  stomach  of  ruminants  is  compound,  and  consists  of  four  cavities. 
The  intestine  is  shorb  in  flesh-eating  animals  and  long  in  herbivora.  The  cfficum  is 
a  very  large  and  important  digestive  organ  in  herbivora,  and  in  most  rodents; 
it  is  small  in  man,  and  absent  in  carnivora.  The  oesophagus  in  grain-eating 
Birds  not  unfrequently  has  a  blind  diverticulum  or  crop  for  softening  the  food. 
In  the  crop  of  pigeons  during  the  breeding  season,  there  is  formed  a  peculiar 
secretion — "pigeon's  milk,"  which  is  used  to  feed  the  young  (J.  Hunter).     The 


384  HISTORICAL  ACCOUNT  OF  DIGESTION. 

stomach  consists  of  a  glandular  proventriculus  and  a  strong  muscular  stomach 
which  is  covered  with  horny  epithelium  and  triturates  the  food.  There  are 
usually  two  fluid  diverticula  on  the  small  intestine  near  where  it  joins  the  large 
gut.  In  Fishies  the  intestinal  canal  is  usually  simple ;  the  stomach  is  merely  a 
dilatation  of  the  tube ;  and  at  the  pylorus  there  may  be  one,  but  usually  many, 
bliud  glandular  appendages  (the  appendices  pyloricas).  There  are  usually  longi- 
tudLual  folds  in  the  intestinal  mucous  membrane,  but  in  some  fishes,  e.g.,  the  shark, 
there  is  a  spb-al  valve.  [It  is  curious  to  find  that  the  ruversive  (cane-sugar)  fer- 
ment is  wanting  ia  the  herbivora,  as  the  cow,  horse,  and  sheep,  but  is  present  in 
the  carnivora,  as  the  dog  and  cat.  It  is  also  met  with  in  birds  and  reptiles,  and 
in  many  of  the  invertebrates,  as  the  ordinary  earth-worm  (Matthew  Hay).] 

In  AmpMbia  and  Reptiles  the  stomach  is  a  simple  dilatation;  the  gut  is  larger 
in  vegetable  feeders  than  in  flesh  feeders.  The  liver  is  never  absent  in  vertebrates, 
although  the  gaU-bladder  frequently  is.     The  pancreas  is  absent  in  some  fishes. 

Digestion  in  Plants. — The  observations  on  the  albumin-digesting  power  of 
some  plants  (Canby,  1869;  Ch.  Darwin,  1875)  are  extremely  interesting.  The 
sundew  or  drosera  has  a  series  of  tentacles  on  the  surface  of  its  leaves,  and  the 
tentacles  are  provided  with  glands.  As  soon  as  an  insect  alights  upon  a  leaf  it  is 
suddenly  seized  by  the  tentacles,  the  glands  pour  out  an  acid  juice  over  the  prey, 
which  is  gradually  digested ;  all  except  the  chitinous  structures.  The  secretion,  as 
well  as  the  subsequent  absorption  of  the  products  of  digestion,  are  accomplished  by 
the  activity  of  the  protoplasm  of  the  cells  of  the  leaves.  The  digestive  juice  con- 
tains a  pepsin-like  ferment  and  formic  acid.  Similar  phenomena  are  manifested 
by  the  Venus  flytrap  (Dionaea),  by  pinguicula,  as  well  as  by  the  cavity  of  the 
altered  leaves  of  nepenthes.  About  fifteen  species  of  these  "  insectivorous"  or 
carnivorous  plants  are  known. 

188.  Historical. 

Digestion  in  the  Mouth.  — The  Hippocratic  school  was  acquamted  with  the 
vessels  of  the  teeth ;  Aristotle  ascribed  an  uninterrupted  growth  to  these  organs,  and 
he  farther  noticed  that  animals  that  were  provided  with  horns,  and  had  cloven 
hoofs,  had  an  imperfect  set  of  teeth — the  upper  incisors  were  absent.  It  is  curious 
to  note  that  in  some  cases  where  men  have  had  an  excessive  formation  of  hairy 
appendages,  the  incisor  teeth  have  been  found  to  be  badly  developed.  The  muscles 
of  mastication  were  known  at  an  early  period ;  Vidius  (+1567)  described  the  tempero- 
maxillary  articulation  with  its  meniscus.  The  older  observers  regarded  the  saliva 
as  a  solvent,  and  in  addition,  many  bad  qualities,  especially  in  starving  animals, 
were  ascribed  to  it.  This  arose  from  the  knowledge  of  the  saliva  of  mad  animals, 
and  the  parotid  saliva  of  poisonous  snakes.  Human  saliva,  without  organisms,  is 
poisonous  to  birds  (Gautier).  The  salivary  glands  have  been  known  for  a  long 
time.  Galen  (131-203  a.d.)  was  acquainted  with  Wharton's  duct,  and  Aetius 
(270  A.D. )  with  the  sub-maxUlary  and  sub-lingual  glands.  Hapel  de  la  Chenaye  (1780) 
obtained  large  quantities  of  saliva  from  a  horse,  in  which  he  was  the  first  to  make  a 
salivary  fistula.  Spallanzani  (1786)  asserted  that  food  mixed  with  saliva  was 
more  easily  digested  than  food  moistened  with  water.  Hamberger  and  Siebold 
investigated  the  reaction,  consistence,  and  specific  gravity  of  saliva,  and  found  in 
it  mucus,  albumin,  common  salt,  calcium,  and  sodium  phosphates.  Berzelius 
gave  the  name  ptyalin  to  the  characteristic  organic  constituent  of  saliva,  but 
Leuchs  (1S31)  was  the  first  to  detect  its  diastatic  action. 

Gastric  Digestion. — Digestion  was  formerly  compared  to  boiling,  whereby 
solution  was  effected.  According  to  Galen,  only  substances  that  have  been  dis- 
solved passed  through  the  pylorus  into  the  intestine.  He  described  the  move- 
ments of  the  stomach  and  the  peristalsis  of  the  intestines.     Aelian  gave  names  to 


HISTORICAL.  385 

the  four  stomachs  of  the  ruminants.  Vidius  (t  1567)  noticed  the  numerous  small 
apertures  of  the  gastric  glands.  Van  Helmont  (t  1644)  expressly  notices  the 
acidity  of  the  stomach.  Eeaumur  (1752)  knew  that  a  juice  was  secreted  by  the 
stomach,  which  eEFected  solution,  and  with  which  he  and  Spallanzani  performed 
experiments  on  digestion  outside  the  body.  Carminati  (1785)  found  that  the 
stomachs  of  carnivora  during  digestion  secreted  a  very  acid  juice.  Prout  (1824) 
discovered  the  hydrochloric  acid  of  the  gastric  juice,  Sprott  and  Boyd  (1836)  the 
glands  of  the  gastric  mucous  membrane,  while  Wasmann  and  Bischoff  noted  the  two 
kinds  of  gastric  glands.  After  Beaumont  (1834)  had  made  his  observations  upon 
Alexis  St.  Martin,  who  had  a  gastric  fistula,  caused  by  a  gunshot  wound,  Bassow 
(1842)  and  Blondlot  (1843)  made  the  first  artificial  gastric  fistulse  upon  animals. 
Eberle  (1834)  prepared  artificial  gastric  juice.  Mialhe  called  albumin,  when 
altered  by  gastric  digestion,  albuminose;  Lehmann,  who  investigated  this  sub- 
stance more  carefully,  gave  it  the  name  j>eptone.  Schwann  isolated  pepsin  (1836), 
and  established  the  fact  of  its  activity  in  the  presence  of  hydrochloric  acid. 

Pancreas,  Bile,  Intestinal  Digestion.— The  pancreas  was  known  to  the 

Hippocratic  School;  Maur.  Hoffmann  (1642)  demonstrated  its  duct  (fowl),  and 
Wirsung  described  it  in  man.  Regner  de  Graaf  (1664)  collected  the  pancreatic 
juice  from  a  fistula,  and  Tiedmann  and  Gmelin  found  it  to  be  alkaline,  while 
Leuret  and  Lassaigne  found  that  it  resembled  saliva.  Valentin  discovered  its 
diastatic  action,  Eberle  its  emulsionising  power,  and  CI.  Bernard  (1846)  its  tryptic 
and  fat-splitting  properties.  The  last-mentioned  function  was  referred  to  by 
Purkinje  and  Pappenheim  (1836). 

Aristotle  characterised  the  bile  as  a  useless  excretion;  according  to  Erasistratua 
(304  B.C.),  fine  invisible  channels  conduct  the  bile  from  the  liver  into  the  gall- 
bladder. Aretaeus  ascribed  icterus  to  obstruction  of  the  bile-duct.  Benedetti 
(1493)  described  gall-stones.  According  to  Jasolinus  (1573),  the  gall-bladder  is 
emptied  by  its  own  contractions.  Sylvius  de  la  Boe  noticed  the  lymphatics  of  the 
liver  (1640);  Walaeus,  the  connective-tissue  of  the  so-called  capsule  of  Glisson 
(1641).     Haller  indicated  the  uses  of  bile  in  the  digestion  of  fats. 

The  liver-cells  were  described  by  Henle,  Purkinje,  and  Dutrochet  (1838). 
Heynsius  discovered  the  urea,  and  CI.  Bernard  (1853)  the  sugar  in  the  liver,  and  he 
and  Hensen  (1857)  found  glycogen  in  the  liver.  Kiernan  gave  a  more  exact  descrip- 
tion of  the  hepatic  blood-vessels  (1834).  Beale  injected  the  lymphatics,  and  Gerlach 
the  finest  bile-ducts.  Schwann  (1844)  made  the  first  biliary  fistula;  Demarcay 
particularly  referred  to  the  combination  of  the  bile  acids  with  soda  (1838);  Strecker 
discovered  the  soda  compounds  of  both  acids,  and  isolated  them. 

Corn.  Celsus  mentions  nutrient  enemata  (3-5  a.d.)  Fallopius  (1561)  described 
the  valvulas  conniventes  and  villi  of  the  intestinal  mucous  membrane,  and  the 
nervous  plexus  of  the  mesentery.  The  agminated  glands  or  patches  of  Peyer  were 
known  to  Severinus  (1645). 


25 


Physiology  of  Absorption. 


189.  The  Organs  of  Absorption. 

The  mucous  membrane  of  the  whole  intestinal  tract,  as  far  as  it  is 
covered  by  a  single  layer  of  columnar  epithelium — i.e.,  from  the 
cardiac  orifice  of  the  stomach  to  the  anus — is  adapted  for  absorption. 
The  mouth  and  oesophagus,  lined  as  they  are  by  stratified  squamous 
epithelium,  are  much  less  adapted  for  this  purpose.  Still,  poisoning  is 
caused  by  placing  potassium  cyanide  in  the  mouth. 

The  channels  of  absorption  in  the  intestinal  tract  are — (1)  the 
capillary  blood-vessels;  and  (2)  the  ladeals  of  the  mucous  membrane. 
Almost  the  whole  of  the  substances  absorbed  by  the  former  pass  into 
the  rootlets  of  the  portal  vein,  and  traverse  the  liver,  while  those 
that  enter  the  lacteals  really  pass  into  lymj)hatics,  so  that  the  chyle 
passes  through  the  thoracic  duct,  and  is  poured  by  it  into  the  blood, 
where  the  thoracic  duct  joins  the  subclavian  vein. 

Watery  solutions  of  salts — e.g.,  potassium  iodide  (in  yq-I^  hours), 
grape-sugar,  poisons,  peptones,  and  in  a  still  higher  degree,  alcoholic 
solutions  of  poisons  are  absorbed  from  the  stomach. 

The  greatest  area  of  absorption  is  undoubtedly  the  small  intestine, 
especially  its  upper  half  (Landois  and  L6pine). 

190.  Structure  of  the  Small  and  Large  Intestines. 

[The  wall  of  the  small  intestine  consists  of  four  coats ;  which  from 
without  inwards  are  named  serous,  muscular,  sub-mucous,  and  mucous. 

The  serous  coat  has  the  same  structure  as  the  peritoneum — i.e.,  a  thin  basis  of 
fibrous  tissue  covered  on  its  outer  surface  by  endothelium. 

The  musCTllar  coat  consists  of  a  thin  outer  longitudinal  and  an  inner  thicker 
circular  layer  of  non-striped  muscular  fibres. 

The  sub-mncous  coat  consists  of  loose  connective-tissue  containing  large  blood- 
vessels and  nerves,  and  it  connects  the  muscular  with  the  mucous  coat.] 

The  mucous  coat  is  the  most  internal  coat,  and  its  absorbing  surface  is  largely 
increased  by  the  presence  of  the  valvulse  conniventes  and  villi.  [The  valmil(B 
conniventes  are  permanent  folds  of  the  mucous  membrane  of  the  small  intes- 
tine, arranged  across  the  long  axis  of  the  gut.  They  jjass  round  a  half 
or  more  of    the    inner    surface    of   the    gut.      They  begin  a  little  below  the 


STRUCTURE   OF  THE   SMALL   INTESTINE. 


387 


commencement  of  the  duodenum,  and  are  large  and  well  marked  in  the 
duodenum,  and  remain  so  as  far  as  'the  upper  half  of  the  jejunum,  where 
they  begin  to  become  smaller,  and  finally  disappear  about  the  lower  part 
of  the  ileum.]  The  villi 
are  characteristic  of  the 
small  intestine,  and  are 
confined  to  it ;  they  occur 
everywhere  as  closely-set 
projections  over  and  be- 
tween the  valvulffi  conni- 
ventes  (Fig.  149).  When 
the  inner  surface  of  the 
mucous  membrane  is 
examiaed  in  water,  it 
has  a  velvety  appearance 
owing  to  their  presence. 
[They  vary  in  length 
from  ^  to  aV  of  an  inch, 
are  most  numerous  and 
largest  in  the  upper  part 
of  the  intestine,  duo- 
denum, and  jejunum, 
where  absorption  is  most 
active,  but  they  are  less 
abundant  in  the  ileum. 
Their  total  number  has 
been  calculated  at  four 
millions  by  Krause.] 
Each  ^^llus  is  a  projection 
of  the  entire  mucous 
membrane,  so  that  it 
contains  mthin  itself 
representatives  of  all  the 
tissue  elements  of  the 
mucosa.  The  orifices  of 
the  glands  of  Lieberkiihn  open  between  the  bases  of  villi  (Fig,  151). 

Each  villus,  be  it  cylindrical  or  conical  in  shape,  is  covered  by  a  single  layer 
of  columnar  epithelium,  whose  protoplasm  is  reticulated,  and  contains  a  well- 
defined  nucleus  with  an  intranuclear  plexus  of  fibrils.  The  ends  of  the  epithelial 
cells  directed  towards  the  gut  are  polygonal,  and  present  the  appearance  of  a 
mosaic  (Fig.  150,  D).  When  looked  at  from  the  side,  their  free  surface  is  seen  to  be 
covered  ^^ith  a  clear,  highly  refractive  disc  or  "  cuticula,"  which  is  marked  with 
Vertical  stria;.  These  striae  were  supposed  by  Kolliker  to  represent  pores  for  the 
absorption  of  fatty  particles,  but  this  has  not  been  confirmed,  while  Brettauer  and 
Steinach  regarded  them  as  produced  by  prisms  placed  side  by  side. 

According  to  some  observers  (v.  Thanhoffer),  however,  this  clear  disc  is  the 
optical  expression  of  a  thinning  of  the  cell  membrane,  comparable  to  the  thickened 
flange  around  the  bottom  of  a  vessel,  such  as  is  used  for  collecting  gases.  On  this 
supposition,  the  upper  end  of  each  cell  is  open,  and  from  it  there  projects  pseudo- 
podia-like  bundles  of  protoplasmic  processes  (Fig.  150,  B).  These  processes  are 
supposed  to  be  extended  beyond  the  margin  of  the  cell  and  again  rapidly  retracted, 
and  in  so  acting  they  are  said  to  carry  the  fatty  particles  into  the  interior  of  the 
cells,  much  as  the  pseudopodia  of  an  amoeba  entangles  its  food.  [This  view  has 
not  been  confirmed  by  a  sufiicient  number  of  observers.]  Between  the  epithelial 
ceils  are  the  so-called  goblet-cells  (Fig.  150,  C).     [Each  goblet-cell  is  more  or  less 


Fig.  149. 
^Mucous  membrane  of  the  small  intestine  of  the  dog; 
the  lacteals  are  black  and  the  blood-vessels  lighter — 
a,  artery;  b,  lymphatic;  c,  plexus  of  capillaries  in 
the  villi ;  d,  lacteal ;  e,  Lieberkiihn's  glands. 


388 


STRUdTURE   OF  A   VlLLltS* 


like  a  chalicie,  narrower  above  and  below,  and  broad  in  the  middle,  witt  a  tapering 
fixed  extremity.  The  outer  part  of  each  cell  is  filled  with  a  clear  substance  or 
mucigen,  which,  on  the  addition  of  water,  yields  mucus.  The  mucigen  lies  in  the 
intervals  of  a  fine  net-work  of  fibrils,  which  pervades  the  cell  protoplasm.  The 
protoplasm,  containing  a  globular  or  triangular  nucleus,  is  pushed  into  the  lower  part 


Scheme  of  an  intestinal  villus — A,  Transverse  section  of  part  of  a  villus ;  a, 
columnar  epithelium  with,  i,  clear  disc ;  c,  goblet-cell ;  i,  i,  adenoid  reti- 
culum ;  d,  d,  spaces  within  the  same  and  containing  leucocytes,  e,  e;  /,  section 
of  the  central  lacteal ;  B,  scheme  of  a  cell  with  processes  supposed  to  be 
projected  from  its  interior ;  C,  columnar  epithelium  after  the  absorption  of 
fatty  granules ;  D,  the  columnar  epithelium  of  a  villus  seen  from  above  with 
a  goblet-cell  in  the  centre. 


of  the  cell.  These  goblet-cells  are  simply  altered  columnar  epithelial  cells,  which 
secrete  mucus  in  their  interior.  They  are  more  numerous  under  certain  conditions. 
Not  unfrequently  in  sections  of  the  mucous  membrane  of  the  gut,  after  it  is  stained 
with  logwood,  we  may  see  a  deep  blue  plug  of  mucus  partly  exuded  from  these 
cells.  When  looked  at  from  above  they  give  the  appearance  seen  in  Fig.  150,  D.] 
The  epithelial  cells  are  shed  in  enormous  numbers  in  cholera,  and  ia  poisoning 
with  arsenic  and  muscarin  (Bohm). 

[The  epithelial  cells  covering  the  villus  are  placed  upon  a  layer  of  squamous 
epithelium  (basement  membrane)— the  sub-epithelial  membrane  of  D^bove.  This 
basement  membrane  is  said  to  be  connected  by  processes  with  the  so-called 
branched  cells  of  the  adenoid  tissue  of  the  villus,  while  it  also  sends  up  processes 
between  the  epithelial  covering.] 

The  villus  itself  consists  of  a  basis  of  adenoid  tissue,  containing  in  its  centre  one 


STRUCTURE   OF   A   VILLUS, 


389 


or  more  lacteals,  closely  invested  with  a  few  longitudinal  smooth  muscular  fibres, 
derived  from  the  muscularis  mucosae,  and  a  plexus  of  blood-vessels. 

The  adenoid  tissue  of  the  villus  consists  of  a  reticulum  of  fibrils  with  endothelial 
plates  at  its  nodes.  The  spaces  of  the  adenoid  tissue  form  a  spongy  net-work  of 
inter-communicating  channels  containing  stroma-cells  or  leucocytes  (Fig.  150,  A,  e,  e). 
These  leucocytes  or  lymph- corpuscles  have  been  seen  to  contain  fatty  granules, 
and  they  may,  perhaps,  play  an  important  part  in  the  absorption  of  fatty  particles. 

The  lymphatic  or  lacteal  lies  in  the  axis  of  the  villus  (Fig.  149,  d).  By  some 
observers,  the  lacteal  is  regarded  merely  as  a  space  in  the  centre  of  the  villus, 
but  more  probably  it  has  a  distinct  wall  composed  of  endothelial  cells,  with 
apertures  or  stomata  here  and  there  between  the  cell-plates.  These  stomata 
place  the  interior  of  the  lacteal  in  direct  commimication  with  the  spaces  of  the 
adenoid  tissue.  It  is  very  probable  that  white  blood-corpuscles  wander  out 
of  the  blood-vessels  of  the  villi  into  the  spaces  of  the  adenoid  tissue,  where 
they  become  loaded  with  fatty  granules,  and  pass  into  the  central  lacteal. 
Zuwarykin  and  Wiedersheim  suppose  that  the  leucocytes  pass  from  the  par- 
enchyma of  the  villus  towards  the  epithelial  layer,  and  even  between  the 
epithelial  cells,  from  which  they  return  towards  the  axis  of  the  villus,  laden 
with  substances  which  they  have  taken  into  their  interior  (p.  399). 

A  small  artery  placed  eccentrically  passes  into  each  villus.  In  man  it  begins  to 
divide  about  the  middle  of  the  villus,  but  in  animals  it  usually  runs  to  the  apex 
before  it  divides.  The  capillaries  resulting  from  the  division  of  the  artery  form  a 
fine  dense  net-work  placed  superficially,  immediately  under  the  epithelium  of  the 
Burface.     The  blood  is  carried  out  of  a  villus  by  one  or  two  veins  (Fig.  149,  a,  c). 


Fig.  151. 

.Section  of  the  mucous  membrane  of  the  small  intestine,  showing  Lieberkiihn's 
glands — a,  with  irregular  epithelium;  6,  villi,  cut  short;  c,  muscularis  mucosae; 
(2,  sub-mucous  tissue. 


390 


brunner's  glands  and  solitary  follicles. 


Non-striped  muscular  fibres  are  present  in  villi  (Henle).  Some  are  arranged 
longitudinally  from  base  to  apex,  immediately  outside  the  central  lacteal.  When 
they  contract  they  tend  to  empty  the  lacteal  (Briicke).  A  few  muscular  fibres  are 
placed  more  superficially,  and  run  in  a  more  transverse  direction.  [The  muscular 
fibres  of  the  villi  are  direct  prolongations  of  the  muscularis  mucosae]. 

Nerves  pass  into  the  villi  from  Meissner's  plexus  lying  in  the  sub-mucous  coat. 
The  nerves  to  the  villi  are  said  to  have  small  granular  ganglionic  cells  in  their 
course,  and  they  terminate  partly  in  the  muscular  fibres  and  partly  in  the  arteries 
of  the  villi. 

[On  making  a  vertical  section  of  the  muCOUS  niemliraiie  of  the  small  intestine, 
it  is  seen  to  consist  of  a  net-work  of  adenoid  tissue  loaded  with  leucocytes.  This 
tissue  forms  its  basis,  and  in  it  are  placed  vertically  side  by  side,  like  test-tubes  in 
a  stand,  immense  numbers  of  simple  tubular  glands— the  CryptS  of  Lieberktilm 
(Fig.  151).  They  open  above  at  the  bases  of  the  villi,  while  their  lower  extremity 
reaches  almost  to  the  muscularis  mucosae.  Each  tube  consists  of  a  basement  mem- 
brane lined  by  a  single  layer  of  columnar  epithelium,  leaving  a  wide  lumen,  the 
cells  lining  them  being  continuous  with  those  that  cover  the  mucous  membrane. 
Some  goblet-cells  are  often  found  between  the  columnar  epithelium.  Immediately 
below  the  bases  of  the  follicles  of  Lieberkiihn  is  the  muscularis  mucosce,  consisting  of 
two  or  three  narrow  layers  of  non-striped  muscular  fibres  arranged  circularly  and 
longitudinally.  It  is  continuous  with  the  muscularis  mucosse  of  the  stomach,  and 
extends  throughout  the  whole  intestine.     It  sends  fibres  upwards  into  the  ^^lli.] 

[Brunner's  glands  are  compound  tubular  glands  lying  in  and  confined  to  the 
sub-mucous  coat  of  the  duodenum.  Their  ducts  perforate  the  muscularis  mucosas 
to  open  on  the  surface.  They  seem  to  be  the  homologues  of  the  pyloric  glands  of 
the  stomach  (p.  368).] 

[Solitary  follicles  are  small  round  or  oval  white  masses  of  adenoid  tissue, 
with  their  deeper  parts  embedded  in  the  sub-mucosa,  and  their  apices  pro- 
jecting into  the  mucosa  of  the  intestine.     They  begin  at  the  pyloric  end  of  the 


Section  of  a  solitary  follicle  of  the  small  intestine  (human),  showing — a,  lymph- 
follicle  covered  with  epithelium  (6)  which  has  fallen  from  the  villi,  c ;  d, 
Jjieberkilhn's  follicle  ;  e,  muscularis  mucosas ;  /,  sub-mucous  tissue. 


STRUCTURE   OF  PEYER's  GLANDS. 


391 


stomach  and  are  found  thi-oughout  the  whole  intestine.  They  consist  of  small 
masses  of  adenoid  tissue  loaded  with  leucocytes  (Fig.  152).  They  are  well  supplied 
with  blood-vessels  (p.  406),  although  no  lymphatic  vessels  enter  them.  They  are 
surrounded  by  lymphatics,  and,  in  fact,  they  may  be  said  to  hang  into  a  lymph- 
stream.] 


un,r\f\ff^i 


Diagram  of  a  vertical  section  of  the  mucous  membrane  of  the  small  intestine  of  a 
dog,  showing  the  closed  follicles,  aa  :  b,  muscularis  mucosae. 

[Peyer's  glands,  or  agminated  glands,  consist  of  groups  of  lymph-follicles  like 
the  foregoing  (Fig.  153).  The  masses  are  often  more  or  less  fused  together,  their 
bases  lie  in  the  sub-mucosa,  while  their  summits  project  into  the  mucosa,  where 
they  are  covered  merely  by  the  columnar  epithelium  of  the  intestine.  The 
lymph-corpuscles  often  project  betMeen  the  epithelium.  The  patches  so  formed 
have  their  long  axis  in  the  axis  of  the  intestine,  and  they  are  always  placed 
opposite  the  attachment  of  the  mesentery.  Like  the  solitary  glands,  they  are 
well  supplied  with  blood-vessels,  while  around  them  is  a  dense  plexus  of  lymphatics 
or  lacteals.  They  are  most  abundant  in  the  lower  part  of  the  ileum.  These 
glands  are  specially  affected  in  typhoid  fever.] 


Auerbach's  plexus  shown  in  section  (human) — a,  ganglionic  cells ;  b,  nerve  fibres ; . 
c,  section  of  the  circular  muscular  fibres ;  d,  longitudinal  muscular  fibres. 


392 


STRUCTURE    OF    THE   LARGE   INTESTINE. 


Nerves  of  the  Intestine. — Thoughout  the  whole  mtestinal  tract,  there  exists 
the  plexus  myentericus  of  Auerhach  (Fig.  154),  lying  between  the  longitudinal 
and  circular  muscular  coats.     This  plexus  consists  of  non-medullated  nerves  with 

groups  of  ganglionic  cells  at  the  nodes.    Fibres 
are  given  off  by  it  to  the  muscular  coats. 

Connected  by  branches  with  the  foregoing  and 
lying  in  the  sub-mucosa,  is  the  plexus  ofMeissner, 
which  is  much  finer,  the  meshes  being  .wider,  the 
nodes  smaller,  but  also  provided  with  ganglionic 
cells.  It  supplies  the  muscular  fibres  and  arteries 
of  the  mucosa,  including  those  of  the  viUi.  It 
also  supplies  branches  to  Lieberkiihn's  glands 
(Drasch).— Compare  Figs.  131  and  132. 

[Structure  of  the  Large  Intestine.— It  has 

four  coats  like  those  of  the  small  intestine.  The 
serous  coat  has  the  same  structure  as  that  of 
the  small  intestine.  The  muscular  coat  has 
external  longitudinal  fibres  occurring  all  round  the 
gut,  but  they  form  three  flat  ribband-like  longi- 
tudinal bands  in  the  caecum  and  colon.  Inside 
this  coat  are  the  circular  fibres.  The  sub- 
mUCOSa  is  practically  the  same  as  that  of  the 
small  intestine.  The  mUCOsa  is  characterised 
by  negative  characters.  It  has  no  villi  and 
no  Peyer's  patches,  but  otherwise  it  resembles 
structurally  the  small  intestine,  consisting  of  a 
basis  of  adenoid  with  the  simple  tubular  glands 
of  Lieherkiiltn  (Fig.  155).  These  glands  are  very 
numerous  and  somewhat  longer  than  those  of  the 
small  intestine,  and  they  always  contain  far 
more  goblet-cells.  The  cells  lining  them  are 
devoid  of  a  clear  disc.  Solitary  glands  occur 
throughout  the  entire  length  of  the  large  intes- 
tine. At  the  bases  of  Lieberkiihn's  glands  is 
the  muscularis  mucosce.  The  blood-vessels  and 
Lieberkiihn's  gland  from  the  nerves  have  a  similar  arrangement  to  those  in 
large  intestine  (dog).  the  stomach.] 


191.  Absorption  of  the  Digested  Food. 

The  physical  forces  concerned  are  endosmosis,  diffusion,  and  filtration. 

All  the  constituents  of  the  food,  with  the  exception  of  the  fats,  which  in  part 
are  changed  into  a  fine  emulsion,  are  brought  into  a  state  of  solution  by  the  digestive 
processes.  These  substances  pass  through  the  walls  of  the  intestinal  tract,  either 
into  the  blood-vessels  of  the  mucous  membrane  or  into  the  beginning  of  the 
lymphatics.  In  this  passage  of  the  fluids  two  physical  processes  come  into  play — 
endosmosis  and  diffusion  as  well  as  filtration. 

I.  Endosmosis  and  diffusion  occur  between  two  fluids  which  are  capable  of 
forming  an  intimate  mixture  with  each  other,  e.g.,  hydrochloric  acid  and  water, 
but  never  between  two  fluids  which  do  not  form  a  perfect  mixture,  such  as  oil  and 
water.  If  two  fluids  capable  of  mixing  with  each  other,  but  of  different  com- 
positions, be  separated  from  each  other  by  means  of  a  septum  with  physical  pores, 
(which  occur  even  in  a  homogeneous  membrane),  an  exchange  of  the  constituents  in 


FORCES   CONCERNED  IN   ABSORPTION. 


393 


the  fluids  occurs  until  both  fluids  have  the  same  composition.     This  exchange  of 
fluids  is  termed  endosmosis  or  diosmosis. 

If  we  remember  that  within  the  intestinal  tract,  there  are  relatively  concen- 
trated solutions  of  those  substances  which  have  been  brought  into  solution  by 
the  digestive  juices— peptone,  sugar,  soaps,  and  solutions  of  the  salts — while 
separated  from  these  by  the  porous  mucous  membrane  and  the  walls  of  the  blood- 
and  lymph-capillaries  is  the  blood,  which  contains  relatively  less  of  these  sub- 
stances, it  is  clear  that  an  endosmotic  current  must  set  in  towards  the  blood  and 
lymph-vessels. 

Biffasion. — If  the  two  mixible  fluids  are  placed  in  a  vessel,  the  one  fluid  over 
the  other,  but  without  being  separated  by  a  porous  septum,  an  exchange  of  the 
particles  of  the  fluids  also  occurs,  until  the  whole  mixture  is  of  uniform  composi- 
tion.    This  process  is  called  Diffusion. 

Conditions  Influencing  Diffusion. — Graham's  investigations  showed  that  the 
rapidity  of  difli.ision  is  influenced  by  a  variety  of  conditions: — (1)  The  nature  of 
the  fluids  themselves  is  of  importance;  acids  diff"use  most  rapidly;  the  alkaline 
salts  more  slowly;  and  most  slowly,  fluid  albumin,  gelatin,  gum,  dextrin.  These 
last  do  not  crystallise,  and  perhaps  do  not  form  true  solutions.  (2)  The  more 
concentrated  the  solutions,  the  greater  the  diffrision.  (3)  Heat  accelerates,  while 
cold  retards,  the  process.  (4)  If  a  solution  of  a  body  which  difiuses  with  difficulty 
be  mixed  with  an  easily  difi"usible  one,  the  former  diffuses  with  still  greater 
difficulty.  (5)  Dilute  solutions  of  several  substances  diffuse  into  each  other 
without  any  difficulty,  but  if  concentrated  solutions  are  employed,  the  process  is 
retarded.  (6)  Double  salts,  one  constituent  of  which  difi'uses 
more  readily  than  the  other,  may  be  chemically  separated  by 
diffusion. 

The  exchange  of  the  fluid  particles  takes  place  independent! u 
of  the  hydrostatic  pressure.  Fig.  156  represents  an  endosmo- 
meter.  A  glass  cylinder  is  filled  with  distilled  water,  and 
into  this  is  placed  a  flask,  J,  without  a  bottom,  instead 
of  which  a  membrane,  m,  is  tied  on.  A  glass  tube,  R,  is  fixed 
firmly  by  means  of  a  cork  into  the  neck  of  the  flask.  The 
flask  is  filled  up  to  the  lower  end  of  the  tube  with  a  concen- 
trated salt  solution,  and  is  then  placed  in  the  cylindrical 
vessel  until  both  fluids  are  on  the  same  level,  x.  The  fluid 
in  the  tube,  R,  soon  begins  to  rise,  because  water  passes 
through  the  membrane  into  the  concentrated  solution  in  the 
flask,  and  this  independently  of  the  hydrostatic  pressure. 
Particles  of  the  concentrated  salt  solution  pass  into  the 
cylinder  and  mix  with  the  water,  F.  These  outgoing  and 
ingoing  currents  continue  until  the  fluids  without  and  within 
J  are  of  uniform  composition,  whereby  the  fluid  in  R  always 
stands  higher  (e.g.,  at  y),  while  it  is  lowered  in  the  cylinder. 
The  circumstance  of  the  level  of  the  fluid  within  the  tube 
being  so  high  and  remaining  so,  is  due  to  the  fact  that  the 
pores  in  the  membrane  are  too  fine  to  allow  the  hydrostatic 
pressure  to  act  through  them. 

Endosmotic  Equivalent.— Experiment  has  shown,  that 
equal  weights  of  different  soluble  substances  attract  different 
amounts  of  distilled  water  through  the  membrane — i.e.,  a 
known  weight  of  a  soluble  substance  (in  the  flask)  can  be 
exchanged  by  endosmosis  for  a  definite  weight  of  water.  The  term  endosmotic 
equivalent  indicates  the  weight  of  distilled  water  that  passes  into  the  flask  of 
the  endosmometer,  in  exchange  for  a  known  weight  of  the  soluble  substance  (Jolly). 
For  1  gram,  alcohol  4-2  grams,  water  were  exchanged;  while  for  I  gram.  NaCl,  4-3 


Fig.  156. 

Endosmometer  for 

Diffusion. 


394 


ENDOSMOSIS   AND   FILTRATION. 


crams,  water  passed  into  the  endosmometer.     The  following  numbers  give  the 
endosmotic  equivalent  of 


Acid  Potassium  Sulphate,  .  =2*3 
Common  Salt,  .  .  .  =  4*3 
Sugar,  .....=  7'1 
Sodium  Sulphate,   .         .         .      =11 '6 


Magnesium  Sulphate,  .  .  =  11'7 

Potassium        ,,  .  .  =   12*0 

Sulphuric  Acid,    .  .  .  =     0-39 

Potassium  Hydrate,  .  .  =:215"0 


The  amount  of  the  substance  which  passes  through  the  membrane  into  the  water 
of  the  cylinder  is  proportional  to  the  concentration  of  the  solution  (Vierordt).  If 
the  water  in  the  cylinder,  therefore,  be  repeatedly  renewed,  the  endosmosis  takes 
place  more  rapidly,  and  the  process  of  equilibration  is  accelerated.  The  larger  the 
pores  of  the  membrane,  and  the  smaller  the  molecules  of  the  substance  in  solution, 
the  more  rapid  is  the  endosmosis.  Hence,  the  rapidity  of  endosmosis  of  different 
substances  varies — thus,  the  rapidity  of  sugar,  sodiiim  sulphate,  common  salt,  and 
urea  is  in  the  ratio  of  1: 1*1:  5:  9-5  (Eckhard,  Hoffmann). 

The  endosmotic  equivalent  is  not  constant  for  each  substance.  It  is  influenced 
by — (1)  The  temperature,  which  as  it  increases,  generally  increases  the  endosmotic 
equivalent.  (2)  It  also  varies  with  the  degree  of  concentration  of  the  osmotic 
solutions,  being  greater  for  dilute  solutions  of  the  substances  (C.  Ludwig  and 
Cloetta). 

If  a  substance  other  than  water  be  placed  in  the  cylinder,  an  endosmotic  current 
occurs  on  both  sides  until  complete  equality  is  obtained.  In  this  case,  the  currents 
in  opposite  directions  disturb  each  other.  If  two  substances  be  dissolved  in  the 
water  in  the  flask  at  the  same  time,  they  diffuse  into  water  vsdthout  affecting  each 
other.  (3)  It  also  varies  with  membranes  of  varying  porosity.  Common  salt, 
which  gives  an  endosmotic  equivalent  with  a  pig's  bladder =4*3,  gives  6  "4  when 
an  ox  bladder  is  used;  2'9  with  a  swimming  bladder;  and  20*2  with  a  collodion 
membrane  (Harzer). 

Colloids. — There  is  a  number  of  fluid  substances  which,  on  account  of  the  great 
size  of  their  molecules,  do  not  pass,  or  pass  only  with  difficulty,  through  the  pores 
of  a  membrane  impregnated  with  gelatinous  bodies,  which  diffuse  slowly.  These 
substances  are  not  actually  in  a  true  state  of  solution,  but  exist  in  a  very  dilute 
condition  of  imbibition.  Such  substances  are  the  fluid  proteids,  starches,  dextrin, 
gum,  and  gelatin.  These  diffuse  when  no  septum  is  present,  but  diffuse  with 
difficulty  or  not  at  all  through  a  porous  septum.  Graham  called  these  substances 
Colloids,  because  when  concentrated,  they  present  a  glue-like  or  gelatinous  appear- 
ance; farther,  they  do  not  crystallise,  whUe  those  substances  which  diffuse  readily 
are  crystalline,  and  are  called  Crystalloids.  Crystallisable  substances  may  be 
separated  from  non-crystallisable  by  this  process,  which  Graham  called  Dialysis. 
Mineral  salts  favour  the  passage  of  colloids  through  membranes  (Baranetzky). 

That  Endosmosis  takes  place  in  the  intestinal  canal  tract,  through  the 
mucous  membrane  and  the  delicate  membranes  of  the  blood-  and 
lymph-capillaries,  cannot  be  denied.  On  the  one  side  of  the  membrane, 
within  the  intestine,  are  the  highly  diffusible  peptones,  sugar,  and  soaps, 
and  within  the  blood-vessels  are  the  colloids  which  are  scarcely  diffusible,. 
e.g.,  the  proteids  of  blood  and  lymph. 

II.  Filtration  is  the  passage  of  fluids  through  the  coarse  intermolecular  pores  of 
a  membrane  owing  to  pressure.  The  greater  the  pressure,  and  the  larger  and  more 
numerous  the  pores,  the  more  rapidly  does  the  fluid  pass  through  the  membrane  ;' 
increase  of  temperature  also  accelerates  it.  Those  substances  which  are  imbibed 
by  the  membrane  filter  most  rapidly,  so  that  the  same  substance  filters  through. 


ABSORPTION  OF  WATER  AND  SOLUBLE  SALTS.        395 

different  membranes  with  varying  rapidity.  The  filtration  is  usually  slower,  the 
greater  the  concentration  of  the  fluid.  The  filter  has  the  property  of  retaining 
some  of  the  substances  from  the  solution  passing  through  it,  ejj.,  colloid  sub- 
stances— or  water  (in  dilute  solutions  of  nitre).  In  the  former  case,  the  filtrate  is 
more  dilute,  in  the  latter,  more  concentrated  than  before  filtration.  Other  sub- 
stances filter  without  undergoing  any  change  of  concentration.  Many  membranes 
behave  difi"erently,  according  to  which  surface  is  placed  next  the  fluid;  thus  the 
shell-membrane  of  an  egg  permits  filtration  only  from  without  inwards ;  [and  the 
same  is  true  to  a  much  less  extent  with  an  ordinary  filter  paper — the  smooth  side 
of  the  filter  paper  ought  always  to  be  placed  next  the  fluid  to  be  filtered].  There 
is  a  similar  difference  with  the  gastric  and  intestinal  mucous  membrane. 

Filtration  of  the  soluble  substance  may  take  place  from  the  canal  of 
the  digestive  tract  when: — (1)  The  intestine  contracts  and  thus  exerts 
pressure  upon  its  contents.  This  is  possible  when  the  tube  is  narrowed 
at  two  points,  and  the  musculature  between  these  two  points  contracts 
upon  the  fluid  contents.  (2)  Filtration,  under  negative  pressure,  may  be 
caused  by  the  villi  (Briicke).  When  the  villi  contract  energetically, 
they  empty  their  contents  towards  the  blood-  and  lymph-vessels.  The 
lymph-vessels  remain  empty,  as  the  chyle  is  prevented  from  passing 
backwards  into  the  origin  of  the  lacteal  within  the  villi,  owing  to  the 
presence  of  numerous  valves  in  the  lymphatics.  When  the  villi  pass 
again  into  the  relaxed  condition,  they  again  become  filled  with  the 
fluids  of  the  intestinal  contents. 

192.  Absorptive  Activity  of  the  Wall  of  the 
Intestine. 

The  process  of  digestion  produces  from  the  food,  partly  solutions  and 
partly  finely  divided  emulsions,  whose  fine  particles  are  surrounded  by 
an  albuminous  envelope,  the  haptogen  membrane  [of  Ascherson],  where- 
by these  particles  become  more  stable.  Unchanged  colloid  substances 
may  also  be  present  in  the  intestinal  tract. 

I.  Aljsorption  of  Solutions. — True  solutions  undoubtedly  pass  by 
endosmosis  into  the  blood-vessels  and  lymphatics  of  the  intestinal  walls, 
but  numerous  facts  indicate,  that  the  protoplasm  of  the  cells  of  the  tube 
take  an  active  part  in  the  process  of  absorption.  The  forces  concerned 
have  not  as  yet  been  referred  simply  to  physical  and  chemical 
processes. 

(1.)  The  Inorganic  Su"bstances. — Water  and  the  soluble  salts  neces- 
sary for  nutrition  are  easily  absorbed.  When  saline  solutions  pass  by 
endosmosis  into  the  vessels,  water  must  pass  from  the  intestinal  vessels 
into  the  intestine.  The  amount  of  water,  however,  is  small,  owing  to 
the  small  endosmotic  equivalent  of  the  salts  to  be  absorbed.  More 
salts  are  absorbed  from  concentrated  than  from  dilute  solutions  (Funke). 


396  ABSORPTION   OF  SOLUBLE  CARBOHYDRATES. 

If  large  quantities  of  salts,  with  a  high  endosmotic  equivalent,  are  intro- 
duced into  the  intestine,  e.g.,  magnesium  or  sodium  sulphate,  these  salts 
retain  the  water  necessary  for  their  solution,  and  thus  diarrhcea  is 
caused  (Poiseuille,  Buchheim).  Conversely,  when  these  substances  are 
injected  into  the  blood  a  large  quantity  of  water  passes  from  the  intes- 
tine into  the  blood,  so  that  constipation  occurs,  owing  to  dryness  of  the 
intestinal  contents  (Aubert).  [M.  Hay  concludes  from  his  experi- 
ments (p,  320),  that  salts,  when  placed  in  the  intestines,  do  not 
abstract  water  from  the  blood,  or  are  themselves  absorbed,  in  virtue  of 
an  endosmotic  relation  being  established  between  the  blood  and  the 
saline  solution  in  the  intestines.  Absorption  is  probably  due  to 
filtration  and  diffusion,  or  processes  of  imbibition  other  than  en- 
dosmosis,  as  yet  little  understood.  The  result  obtained  by  Aubert, 
which  is  not  constant,  is  mostly  caused  by  the  great  diuresis  which 
the  injected  salt  excites.] 

Numerous  inorganic  substances,  whicli  do  not  occur  in  the  body,  are  absorbed  by 
endosmosis  from  the  intestine,  e.g.,  dilute  sulphuric  acid,  potassium  iodide, 
chlorate,  and  bromide  and  many  other  salts. 

(2.)  The  soluble  carbohydrates,  such  as  the  sugars  of  which  the 
chief  representative  is  grape-sugar,  with  a  relatively  high  endosmotic 
equivalent.  Cane-sugar  is  changed  by  a  special  ferment  into  invert 
sugar,  which  is  a  mixture  of  grape-sugar  and  Isevulose  (p.  370). 
Perhaps  a  very  small  proportion  of  the  cellulose  is  changed  into 
grape-sugar.  The  absorption  appears  to  take  place  somewhat  slowly, 
as  only  very  small  quantities  of  grape-sugar  are  found  in  the  chyle- 
vessels  or  the  portal  vein  at  any  time.  According  to  v.  Mering,  the 
sugar  passes  from  the  intestine  into  the  rootlets  of  the  portal  vein ; 
dextrin  also  occurs  in  the  portal  vein.  When  the  blood  of  the  portal 
vein  is  boiled  with  dilute  sulphuric  acid,  the  amount  of  sugar  is  in- 
creased (Naunyn).  The  amount  of  sugar  absorbed  depends  upon 
the  concentration  of  its  solution  in  the  intestine;  hence,  the  amount 
of  sugar  in  the  blood  is  increased,  after  a  diet  containing  much 
of  this  substance  (C.  Schmidt  and  v.  Becker),  so  that  it  may  appear 
in  the  urine,  in  which  case,  the  blood  must  contain  at  least  0'6  per 
cent,  of  sugar  (Lehmann  and  Uhle).  A  small  amount  of  cane-sugar 
has  also  been  found  in  the  blood  (CI.  Bernard,  Hoppe-Seyler).  The 
sugar  is  used  up  in  the  bodily  metabolism ;  some  of  it  is  perhaps 
oxidised  in  the  muscles  (Zimmer). 

(3.)  The  peptones  have  a  small  endosmotic  equivalent  (Funke),  a  2-9 
per  cent,  solution  =  7-10.  Owing  to  their  great  diffusibility,  they  are 
readily  absorbed,  and  they  are  the  chief  representatives  of  the  proteids 
which  are  absorbed.     The  amount  absorbed  depends  upon  the  concen- 


ABSORPTION  OF  PEPTONES  AND  PROTEIDS.  39? 

tratlon  of  their  solution  in  the  intestine.  They  pass  into  the  blood- 
vessels (Schmidt-Miilheim).  When  animals  are  fed  on  peptones  (with 
the  necessary  fat  or  sugar),  they  serve  to  maintain  the  body-weight 
(Maly,  Plosz,  and  Gyorgyai).  Only  minute  quantities  of  peptone  have 
as  yet  been  found  in  the  blood  (DrosdorfF) ;  hence,  it  is  assumed,  either 
that  they  are  rapidly  converted  into  true  albuminous  bodies,  or  that  in 
part  at  least,  they  undergo  further  decompositions,  with  which  we  are 
as  yet  unacquainted.  As,  however,  they  can  compensate  for  the  total 
metabolism  of  the  proteids  within  the  body,  we  must  assume  that  they 
are  converted  into  proteids. 

Schmidt-Mijlheim  has  recently  found  that,  four  hours  after  feeding  a  pig  with 
librin,  a  large  quantity  of  crystalline  propeptone  (p.  331)  can  be  obtained  from 
the  blood.  When  5  c.c.  of  a  20  per  cent,  solution  of  peptone  in  0*6  per  cent. 
NaCl  solution,  for  every  kilo,  of  a  dog,  are  injected  into  the  blood,  death  is  pro- 
duced owing  to  paralysis  of  the  blood-vessels  (compare  28,  11,/).  Fano  is  of 
opinion  that  the  red  blood-corpuscles  take  up  the  peptone,  and  subject  it  to  further 
changes. 

(4.)  Unchanged  true  proteids  filter  with  great  difficulty,  and  much 
albumin  remains  upon  the  filter.  On  account  of  their  high  endosmotic 
equivalent  they  pass  with  extreme  difficulty,  and  only  in  traces  through 
membranes.  Nevertheless,  it  has  been  conclusively  proved  that  un- 
changed proteids  can  be  absorbed  (Briicke),  e.g.,  casein,  soluble  myosin, 
alkali-albuminate,  albumin  mixed  with  common  salt,  gelatin  (Voit, 
Bauer,  Eichhorst).  They  are  absorbed  even  from  the  large  intestine 
(Czerny  and  Latschenberger),  although  the  human  large  intestine 
cannot  absorb  more  than  6  grms.  daily.  But  the  amount  of  unchanged 
proteids  absorbed  is  always  very  much  less  than  the  amount  of 
peptone. 

Egg-albumin  without  common  salt,  syntonin,  serum-albumin,  and  fibrin  are  not 
absorbed  (Eichhorst).  Landois  observed  in  the  case  of  a  young  man  who  took  the 
whites  of  14-20  eggs  along  with  NaCl,  that  albumin  was  given  off  by  the  urine  for 
4-10  hours  thereafter.  The  amount  of  albumin  given  off  rose  until  the  third  day 
and  ceased  on  the  fifth  day.  The  more  albumin  that  was  taken  the  sooner  the 
albuminuria  appeared  and  the  longer  it  lasted.  The  unchanged  egg-albumin 
reappeared  in  the  urine.  If  egg-albumin  be  injected  into  the  blood,  part  of  it 
reappears  in  the  urine  (§  41,  2)  (Stokvis,  Lehmann). 

(5.)  The  soluble  fat-soaps  represent  only  a  fraction  of  the  fats  of 
the  food  which  are  absorbed ;  the  greater  part  of  the  neutral  fats  being 
absorbed  in  the  form  of  very  fine  particles — as  an  emulsion.  The 
absorbed  soaps  have  been  found  in  the  chyle,  and  as  the  blood  of  the 
portal  vein  contains  more  soaps  during  digestion  than  during  hunger, 
it  has  been  assumed  that  the  soaps  pass  into  the  intestinal  blood- 
capillaries.  The  investigations  of  Lenz,  Bidder,  and  Schmidt  render 
it  probable  that  the  organism  can  absorb  only  a  limited  amount  of  fat 
within  a  given  period ;  the  amount  perhaps  bears  a  relation  to  the 


398  ABSORPTION  OF  FATTY  PARTICLES. 

amount  of  bile  and  pancreatic  juice.     The  maximum  per  1  kilo,  (cat) 
was  0"6  grms.  of  fat  per  hour. 

It  appears  as  if  the  soaps  reunite  with  glycerine  in  the  parenchyma 
of  the  villi,  to  form  neutral  fats,  as  Perewoznikoff  and  Will  found,  after 
injecting  these  two  ingredients  into  the  intestinal  canal.  C.  A.  Ewald 
found  that  fat  was  formed  when  soaps  and  glycerine  were  brought  into 
contact  with  the  fresh  intestinal  mucous  membrane.  Perhaps  this  is 
the  explanation  of  the  observation  of  Bruch,  who  found  fatty  particles 
within  the  blood-vessels  of  the  villi. 

Absorption  of  other  Substances. — Of  soluble  substances  which  are  intro- 
duced into  the  intestinal  canal,  some  are  absorbed  and  others  are  not.  The 
following  are  absorbed — alcohol,  part  of  which  appears  in  the  urine  (not  in  the 
expired  air),  viz. ,  that  part  which  is  not  changed  into  CO2  and  H2  0,  within  the 
body ;  tartaric,  citric,  mahc,  and  lactic  acids ;  glycerine,  inulin  (Komanos) ;  gum 
and  vegetable  mucin,  which  give  rise  to  the  formation  of  glycogen  in  the  liver. 

Amongst  colouring  matters  alizarin  (from  madder),  alkannet,  indigo-sulphuric 
acid,  and  its  soda  salt  are  absorbed ;  liEematin  is  partly  absorbed,  whUe  chlorophyll 
is  not.  Metallic  salts  seem  to  be  kept  in  solution  by  proteids,  are  perhaps 
absorbed  along  with  them,  and  are  partly  carried  by  the  blood  of  the  portal  vein 
to  the  liver  (ferric  sulphate  has  been  found  in  chyle).  Numerous  poisons  are  very 
rapidly  absorbed,  e.g.,  hydrocyanic  acid  after  a  few  seconds;  potassium  cyanide 
has  been  found  in  the  chyle. 

II.  Absorption  of  the  smallest  particles.: — The  largest  amount  of  the 
fats  is  absorbed  in  the  form  of  a  milk-like  emulsion  formed  by  the 
action  of  the  bile  and  the  pancreatic  juice,  and  consisting  of  excessively 
small  granules  of  uniform  size  (v.  Frey).  The  fats  themselves  are  not 
qhemically  changed,  but  remain  as  undecomposed  neutral  fats.  The 
particles  seem  to  be  surrounded  by  a  delicate  albuminous  envelope,  or 
haptogen  membrane,  partly  derived  from  the  pancreatic  juice  [probably 
from  its  alkali-albuminate].  The  villi  of  the  small  intestine  are  the 
chief  organs  concerned  in  the  absorption  of  the  fatty  emulsion,  but  the 
epithelium  of  the  stomach  and  that  of  the  large  intestine  also  take  a 
part.  The  fatty  granules  are  recognised  in  the  villi — (1)  Within  the 
delicate  canals?  (p.  387)  in  the  clear  band  of  the  epithelium  (Kolliker). 
[It  is  highly  doubtful  if  the  vertical  lines  seen  in  the  clear  disc  of  the 
epithelium  of  the  intestine  are  due  to  pores.]  (2)  The  protoplasm  of 
the  epithelial  cells  is  loaded  with  fatty  granules  of  various  sizes  during 
the  time  of  absorption,  while  the  nuclei  of  the  cells  remain  free,  although, 
from  the  amount  of  fat  within  the  cells,  it  is  often  difficult  to  distinguish 
them.  (3)  The  granules  pass  into  the  spaces  of  the  parenchyma  of  the 
villi ;  these  spaces  communicate  freely  with  each  other.  (4)  The 
origin  of  the  lacteal  in  the  axis  of  the  villus  is  found  to  be  filled  with 
fatty  granules. 

The  amount  of  fat  in  the  chyle  of  a  dog,  after  a  fatty  meal,  is  8-10 
per  cent.,  while  the  fat  disappears  from  the  blood  within  thirty  hours. 


ABSORPTION  OF  FATTY  PARTICLES.  399 

With    regard    to    the    forces  concerned   in   the   absorption  of  fats, 
V.  Wistinghausen  proved,  that  when  a  porous  membrane  is  moistened 
with  bile,  the  passage  of  fatty  particles  through  it  is  thereby  facilitated, 
but  this  fact  alone  does  not  explain  the  copious  and  rapid  absorption 
of  fats.     It  appears  probable,  that  the  protoplasm  of  the  epithelial  cells 
is  actively  concerned  in  the  process,  and  that  it  takes  the  particles  into 
its  interior.     Perhaps  a  fine  protoplasmic  process  is  thrown  out  by 
these  cells,  just  as  pseudopodia  are  thrown  out  and  retracted  by  lower 
organisms.     It  is  possible  that  absorption  may  take  place  through  the 
open  mouths  of  the  goblet-cells.     The  protoplasm  of  the  epithelial  cells 
is  in  direct  communication  with  the  numerous  protoplasmic  lymph-cells 
within  the  reticulum  of  the  villi,  so  that  the  particles  may  pass  into 
these,  and  from  them  through  the  stomata  (1)  between  the  endothelial 
cells  into  the  central  lacteal  of  the  villus.     According  to  this  view,  the 
absorption  of  fatty  particles,  and  perhaps  also  the  absorption  of  true 
proteids,  is  due  to  an  active  vital  process,  as  indicated  by  the  observa- 
tions of  Briicke  and  v.  Thanhoffer.     This  view  is  supported  by  the 
observation  of  Griinhagen,  that  the  absorption  of  fatty  particles  in  the 
frog  is  most  active  at  the  temperature  at  which  the  motor  phenomena 
of  protoplasm  are  most  lively.     That  it  is  due  to  simple  filtration  alone 
is  not  a  satisfactory  explanation,  for  the  amount  of  fatty  particles  in  the 
chyle  is  independent  of  the  amount  of  water  in  it.      If  absorption  was 
chiefly  due  to  filtration,  we  would   expect  that    there    would   most 
probably  be  a  direct  relation  between  the  amount  of  water  and  the  fat 
(Ludwig  and  Zawilsky).     [The  observations  of  Watney  have  led  him 
to    suppose   that  the   fatty  particles    do  not    pass   through    the   cell 
protoplasm  to  reach  the  lacteal,  but  that  they  pass  through  the  cement- 
substance  between  the  epithelial  cells  covering  a  villus.     If  this  view 
be  correct,  the  absorbing  surface  is  thereby  greatly  diminished.] 

[Schafer  suggests  that  the  leucocytes,  which  have  been  observed 
between  the  columnar  ceUs  of  the  villi  of  the  small  intestine,  are  carriers 
of  at  least  part  of  the  fat  from  the  lumen  of  the  gut  to  the  lacteal ;  they 
also,  perhaps,  alter  it  for  further  use  in  the  economy  (p.  389)]. 

The  activity  of  the  cells  of  the  intestine  with  pseuclopodial  processes  may  be 
studied  in  the  intestinal  canal  of  Distomum  hepaticum.  Sommer  has  figured  these 
pseudopodial  processes  actively  engaged  in  the  absorption  of  particles  from  the 
intestine. 

Spina  observed  that  the  intestinal  epithelium  of  the  larvaj  of  flies  shortened 
when  they  were  stimulated  with  electricity,  and  absorbed  fluid  from  the  intestinal 
canal.     The  cells  of  the  villi  of  the  frog  also  react  to  electrical  stimulation. 

The  increase  in  the  size  of  the  cells  occurs  simultaneously  with  the  contraction 
of  the  intestine.  Spina  also  supports  the  view  that  the  cells,  in  virtue  of  their 
activity,  possess  the  property  of  absorbing  fluid  from  the  intestinal  contents  and 
again  giving  it  up.   An  exchange  of  fluids  in  the  opposite  direction  never  takes  place. 

The  statements  of  former  observers  that  particles  of  charcoal,  pigments,  and 


400  INFLtrENCE   OF  NERVES   ON  ABSORPTION. 

eveu  mammalian .  blood-corpuscles  (in  the  frog)  were  absorbed  by  the  epitheKal 
cells  of  the  intestine,  and  passed  into  the  blood,  are  erroneous.  Even  for  the 
absorption  of  completely  fluid  substances,  endosmosis  and  filtration  seem  to  be 
scarcely  sufficient.  An  active  participation  of  the  protoplasm  of  the  cells  seems 
here  also — in  part  at  least — to  be  necessary,  else  it  is  difficult  to  explain  how  very 
slight  disturbances  in  the  activity  of  these  cells — e.g.,  from  intestinal  catarrh — 
cause  sudden  variations  of  absorption,  and  even  the  passage  of  fluids  into  the 
intestine. 

If  absorption  was  due  to  diffusion  alone,  when  alcohol  is  injected  into  the 
intestiae,  water  ought  to  pass  into  the  intestine,  but  this  does  not  occur,  Brieger 
found  that  the  injection  of  a  O'5-l  per  cent,  solution  of  salts  into  a  ligatured  loop 
of  intestine  did  not  cause  water  to  pass  into  the  intestine;  but  it  appeared  when 
a  20  per  cent,  solution  was  injected. 

193.  Influence  of  the  Nervous  System. 

With  regard  to  the  influence  of  the  nervous  system  upon  intestinal 
absorption  we  know  very  little.  After  extirpation  of  the  semi-lunar 
ganglion  (Budge),  as  well  as  after  section  of  the  mesenteric  nerves 
(Moreau),  the  intestinal  contents  become  more  fluid,  and  are  increased 
in  amount.  This  may  be  partly  due  to  diminished  absorption,  v. 
Thanhofier  states,  that  he  observed  the  protrusion  of  threads  from  the 
epithelial  cells  of  the  small  intestine  only  after  the  spinal  cord,  or  the 
dorsal  nerves,  had  been  divided  for  some  time. 

[Matthew  Hay  injected  saline  solutions  directly  into  the  exposed  intestine.  He 
found  that  a  20  per  cent,  solution  of  sulphate  of  soda  always  excites  a  profuse 
secretion,  but  that  a  10  per  cent,  solution  only  does  so,  or  rather,  that  it  only 
increases  in  bulk,  when  injected  in  sufficient  quantity — a  certain  weight  of  salt 
failing  to  increase  the  bulk  of  the  fluid  secretion  when  dissolved  as  a  10  per  cent, 
solution,  but  exciting  a  profuse  secretion  when  forming  a  20  per  cent,  solution.  Se- 
cretion, he  has  reason  to  believe,  is  active  in  both — perhaps,  almost  equally  active — 
but  absorption  is  greatly  impeded  in  the'case  of  the  concentrated  salt,  by  its  injurious 
action  on  the  absorptive  mechanism  of  the  mucous  membrane.  Moreau  has  recently 
maintained  that,  under  such  circumstances,  there  is  actually  no  absorption,  but 
Hay  has  disproved  this,  by  observing  that  strychnia  injected  into  a  loop  of  intestine, 
containing  the  concentrated  salt,  still  causes  death,  although  after  an  interval  three 
times  longer  than  when  the  loop  contains  a  10  per  cent,  solution  of  the  salt. 

Hay  has  also  observed  that  the  local  effect  of  a  ligature  applied  to  the  intestine 
is  to  excite  secretion  from  the  mucous  membrane  in  its  immediate  vicinity,  and 
therefore  add  to  the  bulk  of  the  saline  solution ;  whereas  the  reflex  effect  of  a 
ligature,  as  exercised  through  the  nervous  system,  is  to  diminish  the  quantity  of 
the  secreted  fluid  in  a  remote  portion  of  the  intestine,  probably  by  stimulating  and 
accelerating  absorption.  Division  of  the  vagi  does  not  affect  the  nature  or  the 
quantity  of  the  secretion]. 

194.  Feeding  with  ''Nutrient  Enemata." 

In  cases  where  food  cannot  be  taken  by  the  mouth — e.g.,  in  stricture  of  the 
oesophagus,  continued  vomiting,  &c.,  food  is  given  per  rectum  (Celsus,  3-5  a.d.). 
As  the  digestive  activity  of  the  large  intestine  is  very  slight,  fluid  food  ought  to 
be  given  in  a  condition  ready  to  be  absorbed,  and  this  ia  beat  done  by  introducing 


LACTEALS  AND   LYMI'IIATICS.  401 

it  into  the  rectum  through  a  tube  with  a  funnel  attached,  and  allowing  the  food 
to  pass  in  slowly  by  its  own  weight.  The  patient  must  endeavour  to  retain  the 
enema  as  long  as  possible.  When  the  fluid  is  slowly  and  gradually  introduced,  it 
may  pass  above  the  ileo-ca3cal  valve. 

Solutions  of  grape-sugar,  and  perhaps  a  small  amount  of  soap  solution,  are 
useful;  and  amongst  nitrogenous  substances  the  commercial  flesh,  bread,  or  milk 
peptones  of  Sanders-Ezn,  Adamkiewicz,  in  Germany,  and  Darby's  fluid  meat  in 
this  country,  are  to  be  recommended.  The  amount  of  peptone  rec^uired  is  I'll 
grms.  per  kilo,  of  body- weight  (Catillon);  less  useful  are  butter-milk,  egg-albumiu 
with  common  salt.  Leube  uses  a  mixture  of  150  grms.  flesh,  with  50  grms. 
pancreas  and  100  grms.  water,  which  he  injects  into  the  rectum  where  the  proteids 
are  peptonised  and  absorbed.  The  method  of  nutrient  enemata  only  permits 
imperfect  nutrition,  and  at  most  only  5  of  the  proteids  necessary  for  maintaining 
the  metabolism  of  the  body  is  absorbed  (v.  Voit,  Bauer). 


195.  Chyle-Vessels  and  Lymphatics. 

Within  the  tissues  of  the  body,  and  even  in  those  tissues  which  do 
not  contain  blood-vessels — e.g.,  the  cornea,  or  in  those  which  contain 
few  blood-vessels,  there  exists  a  system  of  vessels  or  channels  which 
contain  the  juices  of  the  tissues,  and  within  these  vessels  the  fluid 
always  moves  in  a  centripetal  direction.  These  canals  arise  within 
the  tissues  in  a  variety  of  ways,  and  unite  in  their  course  to  form 
delicate  and  afterwards  thicker  tubes,  which  ultimately  terminate  in 
two  large  trunks  which  open  at  the  junction  of  the  jugular  and  sub- 
clavian veins ;  that  on  the  left  side  is  the  thoracic  duct,  and  that  on 
the  right,  the  right  lymphatic  trunk. 

Lymphatics. — With  regard  to  the  lymj^h  and  its  movements  in 
different  organs,  it  is  to  be  noticed  that  this  occurs  in  diff"erent  ways 
in  different  places.  (1)  In  many  tissues,  the  lymphatics  represent  the 
nutrient  channels,  by  which  the  fluid  which  transudes  through  the 
neighbouring  vessels  is  distributed,  as  in  the  cornea  and  in  many 
connective  tissues.  (2)  In  many  tissues,  as  in  glands — e.g.,  the  sali- 
vary glands  (Gianuzzi)  and  the  testis,  the  lymph-spaces  are  the  first 
reservoirs  for  fluid,  from  which  the  cells  during  the  act  of  secretion 
derive  the  fluid  necessary  for  that  process.  (3)  The  lymphatics  have 
the  general  function  of  collecting  the  fluid  which  saturates  the  tissues, 
and  carrying  it  back  again  to  the  blood.  The  capillary  blood-system 
may  be  regarded  as  an  irrigation  system,  which  supplies  the  tissues  with 
nutrient  fluids,  while  the  lymphatic  system  may  be  regarded  as  a 
drainage  apjjaratus,  which  conducts  away  the  fluids  that  have  trans- 
uded through  the  capillary  walls.  Some  of  the  decomposition  pro- 
ducts of  the  tissues,  proofs  of  their  retrogressive  metabolism,  become 
mixed  with  the  lymph-stream,  so  that  the  lymphatics  are  at  the  same 
time  absm'bing  vessels.  Substances  introduced  into  the  parenchyma  of 
the  tissues  in  other  ways,  e.g.,  by  subcutaneous  injection,  are  partly 

26 


402  ORIGIN    OF   THE   LYMPHATICS. 

absorbed  by  the  lymphatics.  A  study  of  these  conditions  shows,  that 
the  lymphatic  system  represents  an  appendix  to  the  Uood-vascular 
system,  and  further,  that  there  can  be  no  lymph  system  when  the 
blood-stream  is  completely  arrested;  it  acts  only  as  a  part  of  the 
whole,  and  with  the  whole. 

Lacteals. — When  we  speak  of  the  lymphatics  proper  as  against 
the  chyle-vessels  or  lacteals,  we  do  so  from  anatomical  reasons,  because 
the  important  and  considerable  lymphatic  channels  coming  from  the 
whole  of  the  intestinal  tract  are,  in  a  certain  sense,  a  fairly  independent 
province  of  the  lymphatic  vascular  area,  and  are  endowed  with  a 
high  absorptive  activity,  which,  from  ancient  times,  has  attracted  the 
notice  of  observers.  The  contents  of  the  chyle- vessels  or  lacteals  are 
mixed  with  a  large  amount  of  fatty  granules,  giving  the  chyle  a  white 
colour,  which  distinguishes  them  at  once  from  the  clear  watery  con- 
tents of  the  true  lymphatics.  From  a  physiological  point  of  view, 
however,  the  lacteals  must  be  classified  with  the  lymphatics,  for,  as 
regards  their  structure  and  function,  they  are  true  lymphatics,  and 
their  contents  consist  of  true  lymph  mixed  with  a  large  amount  of 
absorbed  substances,  chiefly  fatty  granules.  [The  contents  of  the 
lacteals  are  white  only  during  digestion,  at  other  times  they  are  clear 
like  lymph]. 

196.  Origin  of  the  Lymphatics. 

The  mode  of  origin  of  the  lymphatics  varies  within  the  different 
tissues.     The  following  modes  are  known  : — 

1.  Origin  in  Spaces. — Within  the  connective-tissues  (connective-tissue  proper, 
bone),  are  numerous  stellate,  irregular,  or  branched,  spaces  which  communicate  with 
each  other  by  numerous  tubular  processes  (Fig.  157,  s) ;  in  these  communicating 
spaces  lie  the  cellular  elements  of  these  tissues.  These  spaces,  however,  are  not 
completely  filled  by  the  cells,  but  an  interval  exists  between  the  body  of  the  cell 
and  the  wall  of  the  space,  which  is  greater  or  less  according  to  the  condition  of 
movement  of  the  protoplasmic  cell.  These  spaces  are  the  so-called  ^'juice-canals  " 
or  " saftca-ncilchen,"  and  they  represent  the  origin  of  the  lymphatic  vessels  (v. 
Recklinghausen).  As  they  communicate  with  neighbouring  spaces,  the  movement 
of  the  lymph  is  provided  for.  The  cells  which  lie  in  the  spaces,  and  which  were 
formerly  but  erroneously  regarded  by  Virchow  as  the  origins  of  the  lymphatics, 
exhibit  amoeboid  movements.  Some  of  these  cells  remaiu  permanently,  each  in  its 
own  space,  within  which,  however,  it  may  change  its  form — these  are  the  so-called 
''fixed  "  connective-tissue  corpuscles,  and  bone-corpuscles— while  others  merely 
wander  or  pass  into  these  spaces,  andare  called  "  wandering  cells,"  or  "leucocytes;" 
but  the  latter  are  merely  lymph-corpuscles,  or  colourless  blood-corpuscles  which 
have  passed  out  of  the  blood-vessels  into  the  origin  of  the  lymphatics.  These  cells 
exhibit  amoeboid  movements.  These  spaces  conununicate  with  the  small  tubular 
lymphatics — the  so-called  lymph-capillaries  (L).  The  spaces  lie  close  together 
where  they  pass  into  a  lymph- capillary  (a).  The  lymph-capiUary,  which  is 
usually  of  greater  diameter  than  the  blood  capillary,  generally  lies  in  the  middle 


ORIGIN    OF  THE   LYMPHATICS. 


403 


Fig.  157. 

Origin  of  lymphatics — From  the  central  tendon  of  the  diaphragm  of  a  rabbit 
(semi-diagrammatic)  ;  s,  the  juice-canals,  '» communicating  at  x  with  the 
lymphatics;  a,  origin  of  the  lymphatics  by  the  confluence  of  several  juice- 
canals.     The  tissue  has  been  stained  with  nitrate  of  silver. 


Fig.  15S. 

Central  tendon  of  the  diaphragm  of  the  rabbit  stained  with  silver  nitrate  and 
viewed  from  the  pleural  side— L,  lymphatic  with  its  sinuous  endothelium; 
c,  cells  of  the  connective-tissue  brought  into  view  by  the  silver  nitrate. 


404  ORIGIN    OF  THE   LYMPHAtMS. 

of  the  space  within  the  capillary  arch  (B).  The  finest  lymphatics  are  lined  by  a 
layer  of  delicate,  nucleated  endothelial  cells  (e,e),  with  characteristic  sinuous 
margins,  whose  characters  are  easily  revealed  by  the  action  of  silver  nitrate 
(Fig.  158,  L).  This  substance  blackens  the  cement  substance  which  holds  the 
endothelial  cells  together.  Between  the  endothelial  cells  are  small  holes,  or 
stomata,  by  means  of  which  the  lymph-capillaries  communicate  (at  x)  with  the 
juice  canals. 

It  is  assumed  that  the  blood-vessels  communicate  with  the  juice 
canals  (J.  Arnold,  Thoma,  UskofF),  and  that  fluid  passes  out  of  the 
thin-walled  capillaries  through  their  stomata  (p.  122)  into  these  spaces. 
This  fluid  nourishes  the  tissues,  the  tissues  take  up  the  substances 
appropriate  to  each,  while  the  eff"ete  materials  pass  back  into  the 
spaces,  and  from  these  reach  the  lymphatics,  which  ultimately  discharge 
them  into  the  venous  blood. 

Whether  the  cells  within  these  spaces  are  actively  concerned  in  the  pouring 
out  of  the  blood-plasma,  or  take  part  in  its  movement,  is  matter  for  con- 
jecture. We  can  imagine  that  by  contracting  their  body,  after  it  has  been 
impregnated  with  iiuid,  this  fluid  may  be  propelled  from  space  to  space  towards 
the  lymphatics.  The  leucocytes  wander  through  these  spaces  until  they  pass  into 
the  lymphatics.  Fine  particles  which  are  contained  in  these  spaces — e.g.,  after 
tattooing  the  skin  and  even  fatty  particles  after  inunction — are  absorbed  by  the 
leucocytes,  and  carried  by  them  to  other  parts  of  the  body.  [The  pigment 
l^articles  used  to  tattoo  the  finger  are  usually  found  within  the  first  lymphatic 
gland  at  the  elbow.] 

After  what  has  been  said  regarding  the  passage  of  colourless  blood- 
corpuscles  through  the  stomata  of  the  blood-capillaries,  or  through  the 
walls  of  the  smaller  blood-vessels  (§  95),  the  passage  of  cellular 
elements  from  the  blood-vessels  into  the  origin  of  the  lymphatics  is  to 
be  considered  as  a  normal  process  (E.  Hering).  Granular  colouring 
matter  passes  from  the  blood  into  the  protoplasmic  body  of  the  cells 
within  the  lymph-spaces ;  and  only  when  the  granular  pigment  is  in 
large  amount,  does  it  appear  as  a  gi?anular  injection  in  the  branches  of 
the  juice-spaces  (Uskofi"). 

(2.)  The  origin  of  lymphatics  within  villi — i.e.,  of  the  chyle  vessel  ov  lacteal — 
has  been  described  at  p.  389.  The  central  lacteal  communicates  with  the  lacunar 
interstitial  spaces  in  the  adenoid  tissue  of  the  villus,  and  this  again  with  the 
fjrotoplasmic  body  of  the  epithelial  cells.  It  is  assumed  that  the  lymph-corpiiscles, 
which  lie  in  the  meshes  of  the  adenoid  tissue,  pass  into  the  central  lacteal  (His), 
while  new  cells  are  continually  passing  out  of  the  blood-capillaries  of  the  villi  into 
the  tissue,  where  they  perhaps  undergo  increase  through  division. 

(.3.)  Origin  of  lymphatics  in  perivascular  spaces  (Fig.  159). — The  smallest  blood- 
vessels of  bone,  the  central  nervous  system,  retina,  and  the  liver,  are  completely 
surrounded  by  wide  lymphatic  tubes,  so  that  the  blood-vessels  are  completely 
bathed  by  a  lymph-stream.  In  the  brain,  these  lymphatics  are  partly  composed  of 
delicate  connective-tissue  fibres,  which  traverse  the  lymph-space  and  become 
attached  to  the  wall  of  the  included  blood-vessel  (Roth).  Fig.  159,  B,  represents  a 
transverse  section  of  a  small  blood-vessel,  B,  from  the  brain;  p  is  the  divided 
perivascular  sjjace.     This  space  is  called  the  perivascular  space  of  His,  but  in 


PERIVASCULAR   SPACES   AND   STOMATA. 


405 


adtlitioii  to  it,  the  blood-vessels  of  the  brain  have  a  lymph-space  within  the 
adventitia  of  the  blood-vessels  (  Virchoiv-Rohiii's  space).  It  is  partly  lined  by  well- 
defined  endothelium.     Where  the  blood-vessels  begin  to  increase  considerably  in 


Fig,  159. 
Perivascular   lymjihatics — A,  aorta 
of  tortoise ;  B,   artery  from  the 
brain. 


Fig.  160. 
Stomata  from  the  great  lymph-sac  of  a 
frog — a,  stoma  open;  h,  half-closed; 
c,  closed. 


diameter,  they  pass  through  the  wall  of  the  lymphatics,  and  the  two  vessels 
afterwards  take  separate  courses.  In  all  cases,  where  there  is  a  perivascular  space, 
the  passage  of  lymph-  and  blood-corpuscles  into  the  lymphatics  is  greatly  facili- 
tated. In  the  tortoise,  the  large  blood-vessels  are  often  surrounded  with  peri- 
vascular lymphatics.  Fig.  159,  A,  gives  a  representation  of  the  aorta  sur- 
rounded by  a  perivascular  space  (Gegenbaur)  which  is  visible  to  the  unaided  eye. 
In  mammals,  the  perivascular  spaces  are  microscopic. 

(4.)  Origin  in  the  form  of  interstitial  slits  within  organs. — Within  the  testis,  the 
lymphatics  begin  simply  in  the  form  of  numerous  slits,  which  occur  between  the 
coils  and  twists  of  the  seminal  tubules.  They  take  the  form  of  elongated  spaces 
bounded  by  the  curved  cylindrical  surfaces  of  the  tubules.  The  surfaces,  however, 
are  covered  with  endothelium.  The  lymphatics  of  the  testis  get  independent 
walls  after  they  leave  the  parenchyma  of  the  organ.  In  many  other  glands,  tlie 
gland-substance  is  similarly  surrounded  by  a  lymph-space.  The  blood-vessels 
poiir  the  lymph  into  these  spaces  and  from  them  the  secreting  cells  obtain  the 
materials  necessary  for  the  formation  of  their  secretion. 

(5.)  Origin  by  means  oi  free  stomata  on  the  walls  of  the  larger  sei'ous  cavities 
(Fig.  160,  a). — The  investigations  of  v.  Recklinghausen,  Ludwig,  Dybkowsky, 
Schweigger-Seidel,  Dogiel,  and  others  have  shown,  that  the  old  view  of  Mascagni, 
that  the  serous  cavities  freely  communicate  with  the  lymphatics,  is  correct.  The 
investigation  of  the  serous  surfaces,  most  easily  accomplished  on  the  septum  of 
the  great  abdominal  lymph-sac  of  the  frog,  by  means  of  silver  nitrate,  reveals 
the  presence  of  relatively  large  free  openings  or  stomata  lying  between  the 
endothelium.  Each  stoma  is  bounded  by  several  cells,  which  have  a  granular 
appearance,  and  are  capable  of  undergoing  a  change  of  shaj^e,  so  that  the  size 
of  the  stoma  depends  upon  the  degree  of  contraction  of  these  cells;  thus  the 
stoma  may  be  open  (a),  half  open  (b),  or  completely  closed  (c).  These  stomata 
are  the  origin  of  the  lymphatics.  The  serous  cavities  belong  therefore  to  the 
lymphatic  system,  and  fluids  placed  in  the  serovis  cavities  readily  pass  into  the 


406 


LYMPH-FOLLICLES. 


lymphatics.  The  cavities  of  th  peritoneum,  pleura,  pericardium,  tunica  vaginalis 
testis,  arachnoid  space,  aqueous  chambers  of  the  eye  (Schwalbe),  and  the 
labjrrinth  of  the  ear,  are  true  lymph-cavities,  and  the  fluid  they  contain  is  to 
be  regarded  as  lymph. 

(6.)  Free  open  pores  have  been  observed  on  some  mucous  membranes,  which  are 
regarded  as  the  origin  of  lymphatics,  e.g.,  in  the  bronchi  (Klein) — the  nasal 
mucous  membrane  (Hjalmar-Heiberg),  in  the  trachea  and  larynx. 

The  larger  lymphatics  resemble  in  structure  the  veins  of  corresponding  size. 
The  valves  are  particularly  numerous  in  the  lymphatics,  so  that  a  distended 
lymphatic  resembles  a  chain  of  pearls.  [Lymphatics  have  dilations  here  and  there 
in  their  course  (Fig.  158).] 


197.  The  Lymph-Glands. 

The  so-called  lymphatic  glands  belong  to  the  lymph  apparatus. 
They  are  incorrectly  termed  glands,  as  they  are  much  branched 
lacunar  labyrinthine  spaces  merely  composed  of  adenoid  tissue,  and 
intercalated  in  the  course  of  the  lymphatic  vessels. 

There  are  simple  and  compound  lymph-glands. 

(1. )  The  simple  lymph-glands,  or,  more  correctly,  lymph-follicleS,  are  small 
rounded  bodies,  about  the  size  of  a  pin-head.  They  consist  of  a  mass  of  adenoid 
tissue  (Fig.  161,  A),  i.e.,  of  a  very  delicate  net-work  of  fine  reticular  fibres  with 
nuclei  at  their  points  of  intersection,  and  in  the  spaces  of  the  mesh- work  lie  the 
lymph  and  the  lymph-corpuscles.  Near  the  surface,  the  tissue  is  somewhat  denser, 
where  it  forms  a  capsule,  which  is  not  however  a  true  capsule,  as  it  is  permeated 
with  numerous  small  sponge-like  spaces.  Small  lymphatics  come  directly  into 
contact  with  these  lymph-follicles,  and  often  cover  their  surface  in  the  form  of  a 


Fig.  161. 

Two  lymph-follicles — A,  a  small  follicle  highly  magnified,  showing  the  adenoid 
reticulum ;  B,  a  follicle  less  highly  magnified,  showing  injected  blood-vessels. 

close  net-work.  The  surface  of  the  lymph-follicles  is  not  unfrequently  placed  in 
the  wall  of  a  lymph-vessel,  so  that  it  is  directly  bathed  by  the  lymph-stream. 
Although  no  direct  canal-like  opening  leads  from  the  follicle  into  the  lymphatic 
stream,  in  relation  with  it  a  communication  must  exist,  and  this  is  obtained  by  the 
numerous  spaces  in  the  follicle  itself,  so  that  a  lymph-follicle  is  a  true  lymphatic 
apparatus  (Brlicke)  whose  juices  and  lymph-corpuscles  can  pass  into  the  nearest 
lymphatic.     The  follicles  are  surrounded  by  a  net-work  of  blood-vessels  which 


LYMPHATIC   GLANDS. 


407 


sends  loops  of  capillaries  into  their  interior  (Fig.  161,  B).  We  may  assume  that 
lymph-corpuscles  pass  from  these  capillaries  into  the  follicle. 

In  connection  with  these  follicles,  including  those  of  the  back  of  the  tongue, 
the  solitary  glands  of  the  intestine  and  the  adenoid  tissue  in  the  bronchial  tract, 
the  tonsils,  Peyer's  patches,  it  is  important  to  rememl^er  that  enormous  numbers 
of  leucocytes  pass  out  between  the  epithelial  cells  covering  these  follicles.  The 
extruded  leucocytes  undergo  disintegration  subsequently  (Ph.  Stbhr). 

(2. )  The  compound  lymph-glands — the  so-called  lymphatic  glands — represent 
a  collection  of  lymph-follicles,  whose  form  is  somewhat  altered.  Every  Ijrmph- 
gland  is  covered  externally  with  a  connective- tissue  capsule  (Fig.  1G2,  c),  which  con- 
tains numerous  non-striped  muscular  fibres  (0.  Heyfelder).  From  its  inner  surface, 
numerous  sejyta  and  trabecule  (<?•)  pass  into  the  interior  of  the  gland,  so  that  the 
gland-substance  is  divided  into  a  large  number  of  compartments.  These  com- 
partments in  the  cortical  portion  of  the  gland  have  a  somewhat  rounded  form,  and 
constitute  the  alveoli,  while  in  the  medullary  portion  they  have  a  more  elongated 
and  irregular  form.  [On  making  a  section  of  a  lymph-gland  we  can  readily  dis- 
tinguish the  cortical  from  the  medullary  portion  of  the  gland.]  All  the  compart- 
ments are  of  equal  dignity,  and  they  all  communicate  with  each  other  by  means 
of  openings,  so  that  the  septa  bound  a  rich  net-work  of  spaces  within  the  gland, 
which  communicate  on  all  sides  with,  each  other. 


Fig.  162. 

Diagrammatic  section  of  a  lymphatic  gland — a,  I,  afferent ;  e,  I,  efferent  lymphatics ; 
C,  cortical  substance;  M,  reticular  cords  of  medulla;  I,  s,  lymph-sinus;  c, 
capsule,  with  trabeculse,  tr. 

These  spaces  are  traversed  by  the  follicular  threads  (Fig.  163,/,  /).  These  repre- 
sent the  contents  of  the  spaces,  but  they  are  smaller  than  the  spaces  in  which  they 
lie,  and  do  not  come  into  contact  anywhere  with  the  walls  of  the  spaces.  If  we 
imagine  the  spaces  to  be  injected  with  a  mass,  which  ultimately  shrinks  to  one-half 
of  its  original  volume,  we  obtain  a  conception  of  the  relation  of  these  follicular 
threads  to  the  spaces  of  the  gland.  The  blood-vessels  of  the  gland  (6)  lie  within 
these  follicular  threads.  They  are  surrounded  by  a  tolerably  thick  crust  of  adenoid 
tissue,  with  very  fine  meshes  (x,  x)  filled  with  lymph-corpuscles,  and  with  its  surface 
(o,  o)  covered  by  the  cells  of  the  adenoid  reticulum,  in  such  a  way  as  to  leave 
free  communications  through  the  narrow  meshes. 


408 


LYMPHATIC   GLAND. 


Between  the  surface  of  the  follicular  threads  and  the  inner  wall  of  all  the  spaces 
of  the  gland,  lies  the  lymph- channel  or  lymph-ijath  (B,  B),  which  is  traversed  by  a 
reticulum  of  adenoid  tissue,  containing  relatively  few  lymph-corpuscles.  It  is  very 
probable  that  these  lymph-paths  are  lined  by  endothelium  (v.  Reckliughausen). 


Part  of  a  lymjfhatic  gland— A,  Vas  afferens  ;  B,  B,  lymph-spaces  within  the  gland; 
a,  a,  septa  or  trabeculce  seen  on  edge  ;  /,/,  follicular  strand  from  the  medulla; 
X,  X,  its  adenoid  reticulum  ;  h,  its  blood-vessels ;  o,  o,  narrow  meshed  part 
limiting  the  follicular  strands  from  the  lymph-space. 

The  vasa  afferentia  (Fig.  162,  a,  I),  of  which  there  areiisually  several,  expand  upon 
the  surface  of  the  gland,  perforate  the  outer  capsule,  and  pour  their  contents  into  the 
lymph-x^aths  (C)  of  the  gland.  The  vasa  ejferejitia,  which  are  less  numerous  than 
the  afferentia,  and  come  out  at  the  hilum,  form  large,  wide,  almost  cavernous 
flilatations,  and  they  anastomose  near  the  gland  (e,  I).  Through  them  the  lymph 
passes  out  at  the  opposite  surface  of  the  gland.  The  lymph  percolates  through  the 
gland,  and  passes  along  the  lymph-paths,  which  represent  a  kind  of  rete  mirabile 
interposed  between  the  afferent  and  efferent  lymph-vessels. 

During  its  passage  through  this  complicated  branched  system  of  spaces,  the 
movement  of  the  lymph  through  the  gland  is  retarded,  and,  owing  to  the 
numerous  resistances  which  occur  in  its  path,  it  has  very  little  propulsive 
energy.  The  lymph-corpuscles  which  lie  in  the  meshes  of  the  adenoid  reticulum 
are  washed  out  of  the  gland  by  the  lymph-stream  (Brticke).  The  lymph-cor- 
puscles lying  within  the  follicular  threads,  pass  through  the  narrow  meshes  (0) 


PROPERTIES   OF   CHYLE   AND   LYMPH.  409 

into  the  lymph-paths.  The  formation  of  lymph-corpuscles  occurs  either  locally, 
from  division  of  the  pre-existing  cells,  or  new  leucocytes  wander  out  into  the 
follicular  threads.  The  movement  of  the  lymph  through  the  gland  is  favoured  Ijy 
the  muscular  action  of  the  capsule.  When  the  capsule  contracts  energetically,  it 
must  compress  the  gland  like  a  sponge,  and  the  direction  in  which  the  fluid  moves 
is  regulated  by  the  position  and  arrangement  of  the  valves. 

The  researches  of  Teichmann,  His,  Frey,  Brilcke,  and  v.  Recklinghausen  have 
chiefly  contributed  to  the  elucidation  of  the  morphological  and  physiological 
relations  of  the  lymph-glands. 

In  addition  to  the  constituents  of  lymph,  the  following  chemical  substances 
have  been  found  in  lymphatic  glands : — Leucin  (Frerichs  and  Stiideler)  and 
Xanthin. 


198.  Properties  of  Chyle  and  Lymph. 

(1.)  Both  fluids  are  albuminous,  colourless,  clear  juices,  containing 
hjmjjh-corpusdes  (§  9),  which  are  identical  with  the  colourless  blood- 
corpuscles.  In  some  places,  e.g.,  in  the  lymphatics  of  the  spleen,  especially 
in  starving  animals  (Nasse),  and  in  the  thoracic  duct,  a  few  coloured 
blood-corpuscles  have  been  found.  The  lymph-corpuscles  are  supplied  to 
the  lymph  and  chyle,  from  the  lymphatic  glands  and  the  adenoid 
tissue.  They  also  pass  out  of  the  blood-vessels  and  wander  into  the 
lymphatics,  and  as  coloured  blood-corpuscles  have  also  been  seen  to  pass 
out  of  the  blood-vessels  (Strieker,  J.  Arnold),  this  explains  the  occa- 
sional presence  of  these  corpuscles  in  some  lymphatics ;  but  when  the 
pressure  within  the  veins  is  high  near  the  orifice  of  the  thoracic  duct, 
red  blood-corpuscles  may  pass  into  the  thoracic  duct.  In  addition,  the 
chyle  contains  numerous  fatty  granules  each  surrounded  with  an 
albuminous  envelope.  [Thus  the  chyle,  in  addition  to  the  constituents 
of  the  lymph,  contains,  especially  during  digestion,  a  very  large  amount 
of  fat  in  the  form  of  the  finely  emulsionised  fat  of  the  food,  which 
gives  it  its  characteristic  white  or  milky  appearance.  During  hunger, 
the  fluid  in  the  lacteals  resembles  ordinary  lymph.  The  fine  fat 
granules  constitute  the  so-called  "  molecular  basis  "  of  the  chyle.] 

Composition  of  Lymph.— The  lymph  consists  of  a  plasma  with  lijmph- 
corpusdes  suspended  in  it.  The  corpuscles — for  the  most  part  investi- 
gated in  the  form  of  pus-cdls — consist  of  swollen-up  lyroteid  and  soliibh 
paraglohulin,  together  with  lecithin,  cerehrin,  cholesterin,  and  fat,  while  their 
nuclei  yield  midein.  Nuclein  contains  P,  and  is  prepared  by  the 
artificial  digestion  of  pus,  as  it  alone  remains  undigested ;  it  is  soluble 
in  alkalies,  and  is  precipitated  from  this  solution  by  acids.  It  gives  a 
feeble  xanthoproteic  reaction.  When  subjected  to  the  prolonged  action 
of  alkalies  and  acids,  it  yields  substances  allied  to  albumin  and 
syntonin.  Miescher  found  glycogen  in  the  lymph-corpuscles  of  serous 
fluids.       The    lymph-plasma   contains    the    three    fibrin-factors   (§   29), 


410  COMPOSITION   OF   CHYLE. 

derived  very  probably  from  the  breaking  up  of  lymph-corpuscles.  When 
lymph  is  withdrawn  from  the  body,  these  substances  cause  it  to  coagulate. 
Coagulation  occurs  slowly,  owing  to  the  formation  of  a  soft  jelly- 
like, small  "lymph-clot,^'  which  contains  most  of  the  lymph-corpuscles. 
The  exuded  fluid  or  lymph-serum  contains  alJculi-albuminate  (precipitated 
by  acids),  serum-albumin  (coagulated  by  heat),  a,nd  paraglohulin — the  two 
latter  occurring  in  the  same  proportion  as  in  blood-serum;  37  per  cent, 
of  the  coagulable  proteids  is  paraglobulin  (Salvioli).  Peptone  has  been 
found  in  chyle  (?  and  perhaps  also  in  lymph) ;  also  tirea  (Wurtz),  leucin 
and  sugar. 

(2.)  Chyle,  which  occurs  within  the  lacteals  of  the  intestinal  tract 
can  only  be  obtained  in  very  small  amount  before  it  is  mixed  with 
lymph,  and  hence  the  difficulty  of  investigating  it.  A  few  lymph- 
corpuscles  occur  even  in  the  origin  of  lacteals  within  the  villi,  but 
their  number  increases  in  the  vessels  beyond  the  intestine,  more 
especially  after  the  chyle  has  passed  through  the  mesenteric  glands. 
The  amount  of  solids,  which  undergoes  a  great  increase  during  diges- 
tion, on  the  contrary,  diminishes  when  chyle  mixes  with  lymph. 
After  a  diet  rich  in  fatty  matters,  the  chyle  contains  innumerable  fatty 
granules  (2-4  /j,  in  size).  [This  is  the  so-called  "molecular  basis" 
of  the  chyle.]  The  amount  of  fibrin-factors  increases  with  the 
increase  of  lymph-corpuscles,  as  they  are  formed  from  the  breaking-up 
of  the  lymph-corpuscles.  Groh6  found  a  diastatic  ferment  in  chyle, 
which  was  probably  absorbed  from  the  intestine,  occasionally  sugar,  to 
2  per  cent.  (Colin),  and  after  much  starchy  food,  lactates  have  been 
found  (Lehmann), 

The  Chyle  of  a  person  who  was  executed  contained : — 

Water,        .        .        .        90*5  per  cent. 
SoUds,         ...  9-5       „ 

Fibrin trace. 

Albumin, 7'1 

Fats, 0-9 

Extractives,        .         .         .         .  1*0 

Salts, 0-4 

CI.  Schmidt  found  the  following  inorganic  substances  in  1000  parts  of  chyle 
(horse) : — 

Sodic  Chloride, 5*84: 

Soda, 1-17 

Potash 0-13 

Sulphuric  Acid, 0'05 

Phosphoric  ,,  .         .         .         .         .         .         •  0"05 

Calcic  Phosphate, 0-20 

Magnesic      ,, 0*05 

Iron, trace. 


COMPOSITION    OF   LYMPH. 


411 


(3.)  The  Lymph  obtained  from  the  beginning  of  the  lymphatic 
system  also  contains  very  few  lymph-corpuscles ;  it  is  clear,  transparent, 
and  colourless,  and  closely  resembles  the  fluids  of  serous  cavities.  That 
the  lymph  coming  from  different  tissues  varies  somewhat,  is  highly 
probable,  but  this  has  not  been  proved.  After  lymph  has  passed 
through  lymphatic  glands,  it  contains  more  corpuscles,  and  also  more 
solids,  especially  albumin  and  fat.  Ritter  counted  8,200  lymph- 
corpuscles  in  1  cubic  centimetre  of  the  lymph  of  a  dog. 

Hensen  and  Dahnhardt  obtained  pure  lymph  in  considerable  quantity 
from  a  lymphatic  iistula,  in  the  leg  of  a  man.  It  had  an  alkaline 
reaction,  and  a  saline  taste.  It  had  the  following  composition,  which 
may  be  compared  mth  the  composition  of  serous  transudations : — 


Pure  Lympli 
(Hensen  &  Dahnhardt). 

Ceretrospinal  Fluid 
(Hoppe-Seyler). 

Pericardial  Fluid 
(v.  Qorup-Besanez). 

Water,    .         .         .  9S-63 

98-74 

95-51 

Solids,    . 

1-37 

1-25 

4-48 

Fibrin,    . 

Oil 

0-08 

Albumin, 

0-14 

016 

2-46 

A 1  kali-albuininate, 

0  09 

Extractives,    . 

1-26 

Urea,  Leucin, 

1-05 

Salts,      . 

0-SS 

The  cerebrospinal  fluid, 

70  vol.   per  cent,   of  ab- 

and    abdominal  -  lymph 

sorbed  COg,  50"/^  of  which 

contain  a  kind  of   sugar 

could  be  pvunped  out,  and 

(without  the  property  of 

20%  by  the  addition  of  an 

rotating  polarised  light — 

acid. 

Hoppe-Seyler). 

100  parts  of  the  Ash  of  lymph  contained  the  following  substances:— 


Sodium  chloride,     . 

.       74-48 

Phosphoric  acid, 

Soda,       . 

.       10-36 

Sulphuric  acid. 

Potash,   . 

3-26 

Carbonic  acid, 

Lime, 

0-98 

Iron  oxide. 

Magnesia, 

0-27 

109 
1-28 
8-21 
0-06 


Just  as  in  blood,  potash  and  phosplioric  acid  are  most  abundant  in  the 
corpuscles,  while  soda  (chiefly  sodium  chloride)  is  most  abundant  in  the 
lymph-serum.  The  potash  and  phosphoric  acid  compounds  are  most 
abundant  in  cerebro-spinal  fluid,  according  to  C.  Schmidt.  The 
amount  of  water  in  the  lymph  rises  and  falls  with  that  of  the  blood. 
Dog's  lymph  contains  much  CO2 — more  than  40  vols,  per  cent.,  of 
which  17  per  cent,  can  be  pumped  out,  and  23  per  cent,  expelled  by 
acids,  while  there  are  only  traces  of  0  and  1  -2  vols,  per  cent.  N  (Ludwig, 
Hammersten). 


412  QUANTITY  OF  LYMPH  AND  CHYLE. 

The  observation  that  when  lymph  is  collected  from  large  vessels  and  exposed  to 
the  air  it  becomes  red  (Funke)  is  as  yet  unexplained ;  but  it  is  certainly  not  due  to 
the  formation  of  coloured  corpuscles  from  colourless  ones,  owing  to  contact  with 
the  0  of  the  air. 

199.  Quantity  of  Lymph  and  Chyle. 

When  it  is  stated  that  the  total  amount  of  the  lymph  and  chyle 
passing  through  the  large  vessels  in  24  hours  is  equal  to  the  amount  of 
the  blood  (Bidder  and  C.  Schmidt),  it  must  be  remembered  that  this  is 
merely  a  conjecture.  Of  this  amount  one-half  may  be  lymph  and  the 
other  half  chyle.  The  formation  of  lymph  in  the  tissues  takes  place 
continually,  and  without  interruption.  Nearly  6  kilos,  of  lymph  were 
collected  in  24  hours  from  a  lymphatic  fistula  in  the  arm  of  a  woman, 
by  Gubler  and  Quevenne;  70  to  100  grms.  were  collected  in  1|-  to  2 
hours  from  the  large  lymph-trunk  in  the  neck  of  a  young  horse. 

The  following  conditions  aifect  the  amount  of  chyle  and  lymph: — 

(1.)  The  amount  of  chyle  undergoes  very  considerable  increase  during 
digestion,  more  especially  after  a  full  meal,  so  that  the  lacteals  of  the 
mesentery  and  intestine  are  distended  with  white  or  milky  chyle. 
During  hunger,  the  lymph-vessels  are  collapsed,  so  that  it  is  difficult  to 
see  the  large  trunks. 

(2.)  The  amount  of  lymph  increases  with  the  activity  of  the  organ  from 
which  it  proceeds.  Active  or  passive  muscular  movements  greatly 
increase  its  amount.  Lesser  obtained  in  this  way  300  cubic  centi- 
metres lymph  from  a  fasting  dog,  whereby  its  blood  became  so 
inspissated  as  to  cause  death. 

(3.)  All  conditions  which  increase  the  pressure  upon  the  juices  of 
the  tissues  increase  the  amount  of  lymph,  and  vice  versa.  These  con- 
ditions are : — 

(a. )  An  increase  of  the  hlood-'presBure,  not  only  in  the  whole  vascular  system,  but 
also  in  the  vessels  of  the  corresponding  organ,  augments  the  amount  of  lymph  and 
vice  versa  (Ludwig,  Tomsa).  This  however  is  doubtful,  as  has  been  shown  by 
Paschutin  and  Emminghaus.  [In  order  to  increase  the  amount  of  lymph  depend- 
ing upon  pressure  within  the  vessels,  what  must  happen  is  increased  pressure 
within  the  capillaries  and  veins]. 

(6.)  Ligature  or  obstruction  of  the  efferent  veiyis  greatly  increases  the  amount  of 
lymph  which  flows  from  the  corresponding  parts  (Bidder,  Emminghaus).  It  may 
be  doubled  in  amount  (Weiss).  Tight  bandages  cause  a  swelling  of  the  parts  on 
the  peripheral  side  of  the  bandage,  owing  to  a  copious  effusion  of  lymph  into  the 
tissue  (congestive  cedema). 

(c.)  An  increased  supply  of  arterial  blood  acts  in  the  same  way,  biit  to  a  less 
degree.  Paralysis  of  the  vaso-motor  nerves  (Ludwig),  or  stimulation  of  vaso- 
dilator fibres  (Gianuzzi),  by  increasing  the  supply  of  blood  increases  the  amount  of 
lymph  ;  while  diminution  of  the  blood  supply,  owing  to  stimulation  of  vaso-motor 
fibres  or  other  causes,  diminishes  the  amount.  Even  after  ligature  of  both  carotids, 
as  the  head  is  still  supplied  with  blood  by  the  vertebrals,  the  lymph-stream  in 
the  large  cervical  lymphatic,  does  not  cease  (W,  Krause). 


ORIGIN   OF   LYMPH.  •ilS 

(4.)  When  the  total  amount  of  the  blood  is  increased,  by  the  injec- 
tion of  blood,  serum,  or  milk  into  the  arteries,  much  fluid  passes  into 
the  tissues  and  increases  the  formation  of  lymph. 

(5.)  The  formation  of  lymph  still  goes  on  for  a  short  time  after 
death,  and  after  complete  cessation  of  the  action  of  the  heart,  but  only 
to  a  slidit  extent.  If  fresh  blood  be  caused  to  circulate  in  the  body  of 
an  animal,  while  it  is  still  warm,  more  lymph  floAVS  from  the  lymphatics 
(Genersich).  It  appears  as  if  the  tissues  obtained  plasma  from  the 
blood  for  a  time  after  the  stoppage  of  the  circulation.  This  perhaps 
explains  the  circumstance  that  some  tissues,  e.g.,  connective-tissues,  con- 
tain more  fluid  after  death  than  during  life,  whilst  the  blood-vessels 
have  given  out  a  considerable  amount  of  their  plasma  after  death. 

(6.)  The  amount  of  lymph  is  increased  under  the  influence  of  airara 
(Lesser,  Paschutin),  and  so  is  the  amount  of  solids  in  the  lymph.  A 
large  amount  of  lymph  collects  in  the  lymph-sacs  [especially  the  sub- 
lingual] of  frogs  poisoned  with  curara,  which  is  partly  explained  by 
the  fact  that  the  lymph-hearts  are  paralysed  by  curara  (Bidder).  The 
amount  of  lymph  is  also  increased  in  inflamed  parts  (Lassar). 

200.  Origin  of  Lymph. 

(1.)  Origin  of  the  Lymph-Plasma. — The  lymph-plasma  may  be  re- 
garded as  fluid  which  has  been  pressed  through  the  walls  of  the  blood- 
vessels by  the  blood-pressure,  i.e.,  by  fdtration,  into  the  tissues.  The 
salts  which  pass  most  readily  through  membranes,  go  through  nearly 
in  the  same  proportion  as  they  exist  in  blood-plasma — the  fibrin-factors 
to  about  two-thirds,  and  albumin  to  about  one-half  of  that  in  the 
blood.  As  in  the  case  of  other  filtration  processes,  the  amount  of 
lymph  must  increase  with  increasing  pressure.  This  was  proved  by 
Lud^vig  and  Tomsa,  who  found  that  when  they  passed  blood-serum 
under  varying  pressures  through  the  blood-vessels  of  an  excised  testis, 
the  amount  of  transuded  fluid  which  flowed  from  the  lymphatics  varied 
with  the  pressure.  This  "  artificial  lymph  "  had  a  composition  similar  to 
that  of  the  natural  lymph.  Even  the  amount  of  albumin  increased 
with  increasing  pressure.  The  lymph-plasma  is  mixed  in  the  difierent 
tissues  with  the  decomposition  products,  the  results  of  the  metabolism 
of  the  tissues. 

When  the  muscles  are  in  action,  not  only  is  the  lymph  poured  out 
more  rapidly,  but  more  lymph  is  formed.  The  tendons  and  fascise  of 
the  muscles  of  the  skeleton  which  are  provided  with  numerous  small 
stomata,  absorb  the  lymph  from  the  muscles.  By  the  alternate  contrac- 
tion and  relaxation  of  these  fibrous  structures,  they  act  like  suction- 
pumps,  whereby  the  lymphatics  are  alternately  filled,  and  emptied,  while 


414  ORIGIN    OF   THE   LYMPH-CORPUSCLES. 

the  lymph  is  propelled  onwards.  Even  passive  movements  act  in  the 
same  way.  If  solutions  be  injected  under  the  fascia  lata,  they  may  be 
propelled  onwards  to  the  thoracic  duct  by  passive  movements  of  the 
limb  (Ludwig,  Schweigger-Seidel,  and  Genersich). 

(2.)  The  Origin  of  the  Lymph-Corpuscles  varies — 1.  A  very  con- 
siderable number  of  the  lymph-corpuscles  are  derived  from  the  lynvphatic 
glands;  they  are  washed  out  of  these  glands  into  the  vas  efferens 
by  the  lymph-stream,  hence,  the  lymph  always  contains  more  cor- 
puscles after  it  has  passed  through  a  lymph-gland.  Small  isolated 
lymph-follicles  permit  corpuscles  to  pass  through  their  limiting  layer 
into  the  lymph-stream.  2.  A  second  source  is  those  organs  whose 
basis  consists  of  adenoid  tissue,  and  in  whose  meshes  numerous  lymph- 
corpuscles  occur — e.g.,  the  mucous  membrane  of  the  entire  intestinal 
tract,  red  marrow  of  bone,  the  spleen.  In  these  cases,  the  cells  reach 
the  origin  of  the  lymph-stream  by  their  own  amoeboid  movements. 
3.  As  lymph-corpuscles  are  returned  to  the  blood-stream,  where  they 
appear  as  colourless  blood-corpuscles,  so  they  again  pass  out  of  the 
Mood-capillaries  into  the  tissues,  partly  owing  to  their  amoeboid  move- 
ments (Cohnheim),  and  they  are  partly  expelled  by  the  blood-pressure 
(Hering).  In  rare  cases,  lymph-corpuscles  wander  from  lymphatic 
spaces  back  again  into  the  blood-vessels  (v.  Recklinghausen). 

Fine  particles  of  cuinabar  or  milk-globules  introduced  into  the  blood  soon  pass 
into  the  lymphatics,  and  the  vaso-motor  nerves  do  not  affect  the  process.  The 
extrusion  of  particles  is  greater  during  venous  congestion,  just  as  with  diapedesis 
(p.  189),  than  when  the  circulation  is  undisturbed;  inflammatory  affections  of  the 
vascular  wall  also  favour  their  passage.  The  vessels  of  the  portal  system  are 
especially  pervious  (Klitimeyer). 

(4.)  By  increase  of  the  lymph-corpuscles  by  division,  and  also  by 
proliferation  of  the  fixed  connective-tissue  corpuscles  (His),  This  process 
certainly  occurs  during  inflammation  of  many  organs.  This  has  been 
proved  for  the  excised  cornea  kept  in  a  moist  chamber  (v.  Reckling- 
hausen, Hoffmann) ;  the  nuclei  of  the  cornea-corpuscles  proliferate  also 
(Strieker,  Norris).  That  the  connective-tissue  corpuscles  proliferate  is 
shown  by  the  enormous  production  of  lymph-corpuscles  in  acute  in- 
flammations (with  the  formation  of  pus) — e.g.,  in  extensive  erysipelas, 
and  inflammatory  purulent  effusions  into  serous  cavities,  where  the 
number  of  corpuscles  is  too  great  to  be  explained,  by  the  wandering 
of  blood-corpuscles  out  of  the  blood-vessels. 

Decay  of  Lymph-Corpuscles. — The  lymph-corpuscles  disappear  partly 
where  the  lymphatics  arise.  The  occurrence  of  the  fibrin-factors  in 
the  lymph — formed  as  they  are  from  the  breaking-up  of  lymph- 
corpuscles — would  seem  to  indicate  this.  In  inflammation  of  con- 
nective-tissue, in  addition  to  the  formation  of  numerous  new  Ijonph- 


MOVEMENT  OF  CHYLE  AND  LYMPH.  415 

corpuscles,   a  considerable  number  seems  to  be  dissolved;  hence  the 
lymph,  and  also  the  blood,  in  this  case  contains  more  fibrin. 

Lymph-corpuscles  are  also  dissolved  within  the  blood-stream,  and 
help  to  form  the  fibrin-factors. 

201.  Movement  of  Chyle  and  Lymph. 

The  ultimate  cause  of  the  movement  of  the  chyle  and  lymph 
depends  upon  the  difference  of  the  pressure  at  the  origin  of  the 
lymphatics,  and  the  pressure  where  the  thoracic  duct  opens  into  the 
venous  system. 

(1.)  The  forces  which  are  active  at  the  origin  of  the  lymphatics  a,ve 
concerned  in  moving  the  lymph,  but  these  must  vary  according  to  the 
place  of  origin — (a)  The  ladeals  receive  the  first  impulse  towards  the 
movements  of  their  contents — the  chyle — ^from  the  contraction  of  the 
muscular  fibres  of  the  villi  (p.  390).  When  these  contract  and  shorten,  the 
axial  lacteal  is  compressed,  and  its  contents  forced  in  a  centripetal  direc- 
tion towards  the  large  lymphatic  trunks.  When  the  villi  relax  the 
numerous  valves  prevent  the  return  of  the  chyle  into  the  villi. 
{h)  Within  those  lymphatics  which  take  the  form  of  peri-vascular 
spaces,  every  time  the  contained  blood-vessel  is  dilated  the  surrounding 
lymph  will  be  pressed  onwards,  (c)  In  the  case  of  the  pleural 
lymphatics  with  open  mouths,  every  inspiratory  movement  acts  like  a 
suction-pump  upon  the  lymph  (Dybkowsky),  and  the  same  is  the  case 
with  the  openings  (stomata)  of  the  lymphatics  on  the  abdominal  side 
of  the  diaphragm  (Ludwig,  Schweigger-Seidel).  {d)  la  the  case  of 
those  vessels  which  begin  by  means  of  fine  juice-canals,  the  movement 
of  the  lymph  must  largely  depend  upon  the  tension  of  the  juices  of  the 
parenchyma,  and  this  again  must  depend  upon  the  tension  or  ptressure  in 
the  blood-capillaries,  so  that  the  blood-pressure  acts  like  a  vis  a  tergo  in 
the  rootlets  of  the  lymphatics. 

[In  some  organs  peculiar  pumping  arrangements  are  brought  into 
action.  As  already  mentioned,  the  abdominal  surface  of  the  central 
tendon  of  the  diaphragm  is  provided  with  stomata,  or  open  communi- 
cations between  the  peritoneal  cavity  and  the  lymphatics  in  the  sub- 
stance of  the  tendon,  v.  Recklinghausen  found  that  milk  put  upon 
the  peritoneal  surface  of  the  central  tendon  showed  httle  eddies  caused 
by  the  milk-globules  passing  through  the  stomata  and  entering  the 
lymphatics.  The  central  tendon  consists  of  two  layers  of  fibrous  tissue 
arranged  in  different  directions.  When  the  diaphragm  moves  during 
respiration,  these  layers  are  alternately  pressed  together  and  pulled 
apart.  Thus  the  spaces  are  alternately  dilated  and  contracted,  lymph 
being  drawn  into  the  lymphatics  (Fig.  164,  h)  through  the  stomata]. 


416 


MOVEMENT   OE  THE  LYMPH. 


[Lud wig's  Experiment- — Tie  a  respiration  cannula  in  the  trachea  of  a  dead 
rabbit;  cut  across  the  body  of  the  animal  immediately  below  the  diaphragm; 
remove  the  viscera,  and  ligature  the  vessels  passing  between  the  thorax  and 
abdomen;  tie  the  thorax  to  a  ring,  and  hang  it  up  with  the  head  downwards; 


Fig.  164. 

Section  of  central  tendon  of  diaphragm — The  injected  lymph  spaces,  h  and  h,  are 
black.  At /the  walls  of  the  space  are  collapsed  (Brunton,  after  Ludwig  and 
Schweigger-Seidel ) . 

pour  a  solution  of  Berlin  blue  upon  the  peritoneal  surface  of  the  diaphragm; 
connect  the  respiration  cannula  either  with  a  pair  of  bellows  or  an  apparatus  for 
artificial  respiration,  and  imitate  the  respiratory  movements.  After  a  few  minutes, 
the  lymphatics  are  filled  with  a  blue  injection  showing  a  beautiful  plexus.] 

[The  same  kind  of  pumping  mechanism  exists  over  the  costal  pleura 
(p.  224).]    _ 

[The  fascia  covering  the  muscles  is  another  similar  mechanism.  The 
fascia  consists  of  two  layers  of  fibrous  tissue,  with  intervening 
lymphatics  (Fig.  165).     When  a  muscle  contracts,  lymph  is  forced  out 


Fig.  165. 

Injected  lymph  spaces  from  the  fascia  lata  of  the  dog — The  iujected  spaces  are 
black  in  the  figure  (Brunton,  after  Ludwig  and  Schweigger-Seidel). 

from  between  the  layers  of  the  fascia,  while  when  it  relaxes,  the 
lymph  from  the  muscle,  carrying  with  it  some  of  the  waste  products 
of  muscular  action,  passes  out  of  the  muscle  into  the  fascia,  between  the 
now  partially  separated  layers.] 

(2.)  Within  the  lymph-trunks  themselves,  the  independent  contraction 
of  their  muscular  fibres  partly  aids  the  lymph-stream.  Heller  observed 
in  the  mesentery  of  the  guinea-pig,  that  the  peristaltic  movement  of 


MOVEMENT  OF  THE  LYMPH.  417 

the  lymphatic  wall  passed  in  a  centripetal  direction.  The  numerous 
valves  prevent  any  reflux.  The  contraction  of  the  surrounding  muscles, 
and  every  pressure  upon  the  vessels  and  the  tissues  aid  the  current 
(Lud^vig,  Noll),  If  the  outflow  of  blood  from  the  veins  is  interfered 
with,  lymph  flows  copiously  from  the  corresponding  tissues  (Nasse, 
Tomsa),  [If  a  cannula  be  tied  in  a  lymphatic  of  a  dog,  a  few  drops 
of  lymph  flow  out  at  long  intervals.  But  if  even  passive  movements 
of  the  limb  be  made,  e.g.,  simply  flexing  and  extending  the  limb,  the 
outflow  becomes  very  considerable  and  continuous.] 

(3,)  The  lymph-glands,  which  occur  in  the  course  of  the  lymphatics, 
offer  very  considerable  resistance  to  the  lymph-stream,  which  must  pass 
through  the  lymph-paths,  whose  spaces  are  traversed  by  adenoid  tissue, 
and  contain  a  few  lymph-corpuscles.  But  this  is,  to  a  certain  extent, 
compensated  by  the  non-striped  muscle  which  exists  in  the  capsule  and 
trabecule  of  the  glands.  When  they  contract,  they  force  on  the 
lymph,  while  the  valves  prevent  its  reflux.  Enlarged  lymphatic  glands 
have  been  seen  to  contract  when  stimulated  electrically.  [Botkin  has 
stimulated  enlarged  lymphatic  glands  with  electricity  in  cases  of 
leukoemia.] 

(i.)  As  the  lymph-vessels  gradually  join  and  form  larger  vessels, 
and  finally  form  one  trunk,  the  transverse  section,  or  sectional  area, 
diminishes,  so  that  the  velocity  of  the  current  and  the  pressure  are 
increased.  Nevertheless,  the  velocity  is  always  small ;  it  varied  from 
230-300  milHmetres  per  minute  in  the  large  lymphatic  in  the  neck  of 
a  horse  (Weiss),  a  fact  which  enables  us  to  conclude  that  the  move- 
ment must  be  very  slow  in  the  small  vessels.  The  lateral  irressure  at 
the  same  place,  was  10-20  mm.,  and  in  the  dog  5-10  mm.  of  a  weak 
solution  of  soda  (Weiss,  Noll),  although  it  was  found  to  be  12  mm. 
Hg.  in  the  thoracic  duct  of  a  horse  (Weiss). 

(5.)  The  respiratory  movements  exercise  a  considerable  influence  upon 
the  lymph-stream  in  the  thoracic  duct,  and  in  the  right  lymphatic  duct ; 
every  inspiration  favours  the  passage  of  the  venous  blood,  and  also  of 
the  lymph  towards  the  heart,  whereby  the  tension  in  the  thoracic  duct 
may  even  become  negative  (Bidder).  [The  diastolic  suction  of  the  Jieart 
by  diminishing  the  pressure  in  the  veins,  also  favours  the  inflow  of 
lymph  into  the  thorax.] 

(6.)  Lymph -hearts  exist  in  certain  cold-blooded  animals  (Panizza,  Job. 
Miiller).  The  frog  has  two  axillary  hearts  (above  the  shoulder  near  the  vertebral 
column),  and  two  sacral  hearts,  one  on  each  side  of  the  coccyx  near  the  anua. 
They  beat,  but  not  synchronously,  about  60  times  per  minute,  and  contain  10  cubic 
centimetres  of  lymph.  They  have  transversely  striped  muscular  fibres  in  their 
walls,  and  are  also  provided  with  nerve  ganglia  (Waldeyer).  The  posterior  pair 
pump  the  lymph  into  the  branch  of  the  Vena  iliaca  communicans,  and  the  anterior 
pair  into  the   Vena  subscapularis.      Their  pulsation  depends  partly,   but  not 

27 


418  ABSORPTION  OF  PARENCHYMATOUS   EFFUSIONS, 

exclusively,  upon  the  spinal  cord,  for  if  the  cord  be  rapidly  destroyed,  they  may 
cease  to  pulsate  (Volkmann),  but  not  unfrequently  they  continue  to  pulsate  after 
removal  of  the  cord  (Valentin,  Luchsinger).  A  second  source  of  their  pulsatile 
movements  is  to  be  sought  for  in  Waldeyer's  ganglia.  Stimulation  of  the  skin, 
intestine,  or  blood-heart  influences  them  reflexly— partly  accelerating  and  partly 
retarding  them.  If  the  coccygeal  nerve,  which  connects  the  sacral  hearts  to 
the  spinal  cord,  be  divided,  these  effects  do  not  occur  (v.  Wittich).  Strychnia 
accelerates  their  movements  (Scherhej).  Antiar  paralyses  the  lymph-heart  and 
the  blood-heart  at  the  same  time  (Vintschgau),  while  citrara  paralyses  the  former 
alone  (Bidder). 

In  other  amphibians,  there  are  two  lymph-hearts,  in  the  ostrich  and  cassowary 
and  some  swimming  birds  (Panizza),  and  in  the  embryo  chick  (A.  Budge).  They 
occur  in  some  fishes — e.g.,  near  the  caudal  vein  of  the  eel. 

(7.)  The  nervous  system  has  a  direct  effect  upon  the  lymph-stream, 
on  account  of  its  connection  with  the  muscles  of  the  lymphatics  and 
lymph-glands,  and  with  the  lymph-hearts  where  these  exist.  Farther, 
Kllhne  observed  that  the  cornea-corpuscles  contracted  when  the  corneal 
nerves  were  stimulated.  Goltz  also  observed  that  when  a  dilute  solu- 
tion of  common  salt  was  injected  under  the  skin  of  a  frog,  it  was 
rapidly  absorbed,  but  if  the  central  nervous  system  was  destroyed  it 
was  not  absorbed. 

If  inflammation  be  produced  in  the  posterior  extremities  of  a  dog,  and  if  the 
sciatic  nerve  be  divided  on  one  side,  oedema  and  a  simultaneous  increase  of  the 
lymph-stream  occur  on  that  side  (Jankowski). 

Ligature  the  leg  of  a  frog,  except  the  nerves,  so  as  to  arrest  the  circulation,  and 
place  the  leg  in  water;  it  swells  up  very  rapidly,  but  a  dead  limb  does  not  swell 
up.  So  that  absorption  is  independent  of  the  continuance  of  the  circulation. 
Section  of  the  sciatic  nerve,  or  destruction  of  the  spinal  cord  (but  not  section  of 
the  brain),  arrests  absorption  (LaUtenbach). 

202.  Absorption  of  Parenchymatous  Effusions. 

Fluids  which  pass  from  the  blood-vessels  into  the  spaces  in  the  tissues,  or  those 
injected  subcutaneously,  are  absorbed  chiefly  by  the  blood-vessels,  but  also  by  the 
lymphatics.  Small  particles,  as  after  tattooing  with  cinnabar  or  China  ink,  may 
pass  from  the  tissue-spaces  into  the  lymphatics — and  so  do  blood-corpuscles  from 
extravasations  of  blood,  and  fat  granules  from  the  marrow  of  a  broken  bone.  If 
all  the  lymphatics  of  a  part  are  ligatured,  absorption  takes  place  quite  as  rapidly 
as  before  (Magendie);  hence,  absorbed  fluid  must  pass  through  the  thin  membranes 
of  the  blood-vessels.  The  corresponding  experiment  of  ligaturing  all  the  blood- 
vessels, when  no  absorption  of  the  parenchymatous  juices  takes  place  (Emmert, 
Henle,  v.  Dusch),  does  not  prove  that  the  lymphatics  are  not  concerned  in  absorp- 
tion, for,  after  ligaturing  the  blood-vessels  of  a  part,  of  course  the  formation  of 
lymph,  and  also  the  lymph-stream,  must  cease. 

When  fluids  are  injected  under  the  skin,  absorption  takes  place  very  rapidly — 
more  rapidly  than  when  the  substance  is  given  by  the  mouth.  The  subcutaneous 
injection  of  many  drugs  is  now  extensively  used,  but  of  course  the  substances  used 
must  not  corrode,  irritate,  or  coagulate  the  tissues.  Some  substances  do  not  act 
when  given  by  the  mouth,  as  snake  poison,  poisons  from  dead  bodies  or  putrid 
things,  although  they  act  rapidly  when  introduced  subcutaneously.  If  emulsin  be 
given  by  the  mouth,  and  amygdalin  be  injected  into  the  veins  of  an  animal,  hydro- 


(EDEMA   AND   DROPSY,  419 

cyanic  acid  is  not  formed,  as  the  emulsin  seems  to  be  destroyed  in  the  alimentary 
canal.  If  the  emulsin,  however,  be  injected  into  the  blood,  and  the  amygdalin 
be  given  by  the  mouth,  the  animal  is  rapidly  poisoned,  owing  to  the  formation 
of  hydrocyanic  acid,  as  the  amygdalin  is  rapidly  absorbed  from  the  intestinal 
canal.  The  amygdalin,  a  glucoside  (C20H27NO11),  is  acted  upon  by  fresh 
emulsin  like  a  ferment;  it  takes  up  2  (H2  0)  and  yields  hydrocj'anic  acid  (C  H  N), 
+  oil  of  bitter  almonds  (C7H6O),  +  sugar  2  (C6Hi20g) — (CI.  Bernard). 

When  serum  is  injected  subcutaneously,  it  is  rapidly  absorbed;  it  is  decomposed 
within  the  blood-stream,  and  increases  the  amount  of  urea  (p.  62,  2).  Albuminous 
solutions,  oil,  peptones  and  sugars  are  also  absorbed  (Eichhorst). 


203.  Congestion  of  Lymph  and  Serous  Effusions. 

CEdema  and  Dropsy. 

[As  aptly  illustrated  by  Lauder  Brunton,  the  lymph-spaces  may  be  represented 
by  cisterns,  each  of  which  is  provided  with  supply  pipes — the  arteries  and 
capillaries;  while  there  are  two  exit  pipes — the  veins  and  Ijonphatics.  In  health, 
the  balance  between  the  inflow  and  outflow  is  such,  that  the  spaces  are  merely 
moistened  with  fluid.  When  a  cannula  is  placed  in  a  lymphatic  vessel  in  a  dog, 
only  a  few  drops  of  lymph  flow  out  at  long  intervals.  Emminghaus  found  that,  if 
the  veins  of  the  limb  be  ligatured,  the  lymph  flows  much  more  quickly.  This  is 
in  part  due  to  the  increased  transudation  of  fluid  from  the  small  blood-vessels,  but 
as  Brunton  suggests,  it  may  also  be  due  to  fluid  passing  away  by  the  lymphatics 
when  it  can  no  longer  be  carried  away  by  the  veins.  We  cannot  say  what  is  the 
relative  share  of  the  veins  and  lymphatics,  nor  in  the  above  experiment  do  we 
know  how  much  is  due  to  increased  transudation  or  diminished  absorption. 
When  there  is  an  undue  accumulation  of  fluid  in  the  lymph-spaces,  we  have  the 
condition  termed  dropsy.] 

If  the  efferent  veins  and  lymphatics  of  an  organ  be  ligatured,  or  if  resistance  be 
offered  to  the  outflow  of  their  contents,  congestion  and  a  copious  transudation  of 
lymph  into  the  tissues  take  place.  These  are  most  marked  in  the  skin  and  sub- 
cutaneous cellular  tissue.  The  soft  parts  swell  up,  without  pain  or  redness,  and  a 
doughy  swelling,  which  pits  on  pressure  with  the  finger,  results.  These  are  the 
signs  of  lymph-congestion,  which  is  called  cedema  when  the  fluid  is  watery. 

Under  similar  circumstances,  lymph  is  effused  into  the  serous  cavities.  If  at  the 
same  time,  a  large  number  of  colourless  blood-corpuscles  pass  out  of  the  blood- 
vessels into  the  cavity,  the  fluid  becomes  more  and  more  like  pus.  In  order  that 
these  corpuscles  may  proliferate,  a  considerable  percentage  of  albumin  is  neces- 
sary. When  the  pressure  within  the  serous  cavity  rises  above  that  in  the  small 
blood-vessels,  water  may  pass  into  the  blood.  These  sero-purulent  effusions  not 
unfrequently  undergo  changes,  and  yield  decomposition  products,  such  as  leucin, 
tyrosin,  xanthin,  kreatin,  kreatinin  {?),  uric  acid  {?),  urea.  Endothelium  from  the 
sei'ous  cavity  (Quincke),  sugar  in  pleuritic  effusions  (Eichhorst),  and  in  ojdemas 
with  little  albumin  (Rosenbach),  cholesterin  frequently  in  hydrocele  fluid,  and 
succinic  acid  in  the  fluid  of  echinococci  have  all  been  found  in  these  effusions. 

The  effusion  of  lymph  may  arise  not  only  from  pressure  upon  the  lymphatics, 
but  also  from  inflammation  and  thrombosis  of  the  lymphatics  themselves,  in  which 
cases  not  unfrequently  new  Ijnnphatics  are  formed,  so  that  the  communication  is 
re-established.  vSometimes  the  ductus  thoracicus  bursts  and  lymph  is  poured 
directly  into  the  abdomen  or  thorax.  [Ligature  of  the  thoracic  duct  results  in 
rupture  of  the  receptaculum  chyli  and  escape  of  chyle  and  lymph  iato  the  large 
serous  cavities  (Ludwig).] 

When  dropsy  or  effusion  of  fluids  occurs  into  serous  cavities,  there  is  always  a 


420  CONDITIONS  FAVOURING  TRANSUDATION. 

greater  transudation  of  fluid  through  the  blood-vessels.  The  abdominal  blood- 
vessels, and  those  which  yield  a  watery  effusion  under  normal  circumstances,  are 
those  most  liable  to  be  affected. 

Transudation  is  favoured  by — (1)  Venous  congestion,  in  which  case  the  effusion 
usually  contains  little  albumin,  and  few  lymph-corpuscles,  while  the  coloured-cor- 
puscles on  the  contrary  are  more  numerous  the  greater  the  venous  obstruction. 
E-anvier  produced  cedema  artificially  by  ligaturing  the  vena  cava  in  a  dog,  and  at  the 
same  time  dividmg  the  sciatic  nerve.  The  paralytic  dilatation  of  the  blood-vessels 
thereby  produced  caused  an  increased  amount  of  blood  to  pass  to  the  limb,  while  the 
blood-pressure  was  raised,  and  both  factors  favoured  the  transudation  of  fluid. 
[Ranvier's  experiment  proves  that  mere  ligature  of  the  venous  trunk  of  a  limb  by 
itself  is  not  sufficient  to  cause  cedema.  The  oedema  is  due  to  the  concomitant  paralysis 
of  the  vaso-motor  nerves.  If  the  motor  roots  of  the  sciatic  nerve  alone  be  divided 
along  with  ligature  of  the  vena  cava,  no  oedema  occurs,  but  if  the  vaso-motor  fibres 
are  divided  at  the  same  time,  the  limb  rapidly  becomes  cedematous.  There  is  such  an 
increased  transudation  through  the  vascular  walls  that  the  veins  and  lymphatics 
cannot  remove  it  with  sufficient  rapidity,  and  cedema  occurs.  If  there  be  weak- 
ness of  the  vaso-motor  nerves,  slight  obstruction  is  sufficient  to  produce  cedema 
(Lauder  Brunton).]  When  the  leg  veins  are  occluded  with  an  injection  of  gypsum, 
cedema  occurs  (Sotnischewsky).  (2)  Some  unknown  physical  changes  occur  in 
the  protoplasm  of  the  endothelium  of  the  capillaries  and  blood-vessels,  which 
favour  the  transudation  of  albumin,  haemoglobin,  and  even  blood-corpuscles. 
This  occurs  when  abnormal  substances  accumulate  in  the  blood — e.g.,  dissolved 
hsemoglobin— and  when  the  blood  contains  little  0  or  albumin.  The  same  has 
been  observed  after  exposure  to  too  high  temperatures,  and  the  swelling  of 
soft  parts  in  the  neighbourhood  of  an  inflammatory  focus  seems  due  to  the 
transudation  of  fluid  through  the  altered  vascular  wall.  It  is  probable  that  a 
nervous  influence  may  affect  particular  areas,  through  its  action  on  the  blood- 
vessels of  the  part  (it  may  be  upon  the  protoplasm  of  the  blood-capillaries). 
The  transudations  of  this  nature  usually  contain  much  albumin  and  many  lymph- 
corpuscles.  (3)  When  the  blood  contains  a  very  large  amount  of  ivater  the 
tendency  to  transudation  of  fluid  is  increased.  After  a  time  it  may  produce  the 
changes  indicated  in  (2),  and  when  long  continued  may  increase  the  permea- 
bility of  the  vascular  wall  (Cohnheim).  Watery  lymphatic  effusions  from  watery- 
blood — "cachectic  cedema" — occur  in  feeble  and  badly  nourished  individuals. 
[One  of  the  commonest  forms  of  dropsy  is  the  slight  oedema  of  the  legs  in 
antemic  persons,  in  whom  the  heart  and  lungs  are  healthy.  Many  factors  are 
involved — the  watery  condition  of  the  blood,  the  condition  of  nutrition  of  the 
capillaries,  and  probably  a  tendency  to  vaso-motor  paresis  (Brunton).] 

[  (4)  Ostroumoff  found  that  stimulation  of  the  lingual  nerve  not  only  causes  the 
blood-vessels  of  the  tongue  to  dilate,  but  the  corresponding  side  of  the  tongue 
becomes  cedematous.  If  a  solution  of  dilute  hydrochloric  acid  or  quinine  (p.  287) 
be  injected  into  the  duct  of  the  submaxillary  gland,  and  the  chorda  tympani 
stimulated,  there  is  no  secretion  of  saliva,  but  the  gland  becomes  cedematous.  In 
an  animal  poisoned  with  atropin,  stimulation  of  the  chorda  causes  dilatation  of  the 
blood-vessels,  although  there  is  no  secretion  of  saliva,  nevertheless  the  gland  does 
not  become  cedematous  (Heidenhain).  As  Brunton  suggests,  this  experiment 
points  to  some  action  of  atropin  on  the  blood-vessels  which  has  hitherto  been 
entirely  overlooked.] 

204.  Comparative  Physiology. 

In  the  frog,  large  lymph-sacs,  lined  with  endothelium,  exist  under  the  skin, 
while  large  lymph-sacs  lie  in  relation  with  the  vertebral  column— one  on  each  side 


COMPARATIVE   AND  HISTORICAL.  421 

— separated  by  a  tliin  membrane,  perforated  with  stomata,  from  the  abdominal 
cavity.  This  is  the  cysterna  hjmphatica  magna  of  Panizza.  Some  amphibians  and 
many  reptiles  have  large  lymph-spaces  under  the  skin,  which  occupy  the  whole  of 
the  dorsal  region  of  the  body.  All  reptiles  and  the  tailed  amphibians  have  large 
elongated  reservoirs  for  lymph  along  the  course  of  the  aorta.  The  lymph  apparatus 
of  the  tortoise  (Fig.  159)  is  very  extensive. 

The  osseous  fishes  have  in  the  lateral  parts  of  their  backs  an  elongated  lymph- 
trunk,  which  reaches  from  the  tail  to  the  anterior  fins,  and  is  connected  with 
the  dilated  lymphatic  rootlets  in  the  base  of  the  tail  and  in  the  fins.  The  largest 
internal  lymph-sinus  is  in  the  region  of  the  oesophagus.  Many  birds  possess  a 
sinus-like  dilatation  or  lymph-space  in  the  region  of  the  tail.  The  lymph-spaces 
communicate  with  the  venous  system — with  valves  properly  arranged — usually 
in  connection  with  the  upper  vena  cava.  Lymph-hearts  have  already  been 
referred  to  (p.  417). 

In  carnivora,  the  lymph-glands  of  the  mesentery  are  united  into  one  large  com- 
pact mass,  the  so-called  "  pancreas  Asellii." 

205.  Historical. 

Although  the  Hippocratic  School  was  acquainted  with  the  lymph-glands  from 
their  becoming  swollen  from  time  to  time,  and  although  Herophilus  and  Erasis- 
tratus  had  seen  the  mesenteric  glands,  yet  Aselli  (1662)  was  the  first  who  accur- 
ately described  the  lacteals  of  the  mesentery  with  their  valves.  Pecquet  (1648) 
discovered  the  receptaculum  chyli ;  Rudbeck  and  Thorn.  Bartholinus  the  lymphatic 
vessels  (1650—52) ;  Eustachius  (1563)  was  acquainted  with  the  thoracic  duct,  which 
Gassendus  (1654)  maintained  that  he  was  the  first  to  see;  Lister  noticed  that  the 
chyle  became  blue  when  indigo  was  injected  into  the  intestine  (1671) ;  Sommering 
observed  the  separation  of  fibrin  when  lymph  coagulated;  Reuss  and  Emmert 
discovered  the  lymph-corpuscles.  The  chemical  investigations  date  from  the  first 
quarter  of  this  century;  they  were  carried  out  by  Lassaigne,  Tiedemann,  Gmelin, 
and  others.  The  two  last  observers  noticed  that  the  white  colour  of  chyle  was 
due  to  the  presence  of  small  fatty  granules. 


Physiology  of  Animal  Heat. 


206.  Sources  of  Heat. 

Sources.  —  The  heat  of  the  body  is  an  uninterrupted  evolution 
of  kinetic  energy,  which  we  must  represent  to  ourselves  as  due  to 
vibrations  of  the  corporeal  atoms.  The  ultimate  source  of  the  heat 
is  contained  in  the  potential  energy  taken  into  the  body  with  the 
food,  and  with  the  0  of  the  air  absorbed  during  respiration.  The 
amount  of  heat  formed  depends  upon  the  amount  of  energy  liberated 
(see  Introduction). 

The  energy  of  the  food-stuffs  may  be  called    "latent  heat,"  if  we 
assume  that  when  they  are  used  up  in  the  body,  chiefly  by  a  process 

of  combustion,  kinetic 
energy  is  liberated  only 
in  the  form  of  heat.  As 
a  matter  of  fact,  how- 
ever, mechanical  energy 
and  electrical  energy  are 
developed  from  the  poten- 
tial energy.  In  order  to 
obtain  a  unit  measure  for 
the  energy  liberated,  it  is 
advisable  to  express  all 
the  potential  energy  as 
heat-units. 

The  Calorimeter. — This 
instrument  enables  us  to 
transform  the  potential 
energy  of  the  food  into 
heat,  and,  at  the  same 
time,  to  measure  the  num- 
ber of  heat-units  pro- 
duced. 


Favre  and  Silbermann  used  a 

water-calorimeter  (Fig.  166). 

The  substance  to  be  burned 
is  placed  in  a  large  cylindrical 
combustion  chamber  (K),  sus- 
pended in  a  large  cylindrical  vessel  (L)  filled  with  water  (w),  so  that  the  combustion 
chamber  is  completely  surrounded  by  the  water.     Three  tubes  open  into  the  upper 


Fig.  166. 
[  Water  calorimeter  of  Favre  and  Silbermann. 


CALORIMETRY. 


423 


part  of  the  chamber ;  one  of  them  (0)  supplies  the  air  which  is  necessary  for  combus- 
tion, it  reaches  almost  to  the  bottom  of  the  chamber;  the  second  tube  (a)  is  fixed  in 
the  middle  of  the  lid,  and  is  closed  above  with  a  thick  glass  plate,  and  on  this  is 
placed,  at  an  angle,  a  small  mirror  (s)  which  enables  an  observer  to  see  into  the 
interior  of  the  chamber,  and  to  observe  the  process  of  combustion  at  c.  The 
third  tube  (d)  is  used  only  when  combustible  gases  are  to  be  burned  in  the  chamber. 
It  can  be  closed  by  means  of  a  stop-cock.  A  lead  tube  (e,  e)  with  many  twists  on  it, 
passes  from  the  upper  part  of  the  chamber  through  the  water,  and  finally  opens  at 
g.  The  gaseous  products  of  combustion  pass  out  through  this  tube,  and  in  doing 
so  help  to  heat  the  water.  The  cylindrical  vessel  with  the  water  is  closed  with  a 
lid  which  transmits  the  four  tubes.  The  water  cylinder  stands  on  four  feet  within 
a  large  cylinder  (M),  which  is  filled  with  some  good  non-conductor  of  heat,  and 
this  again  is  placed  in  a  large  vessel  filled  with  water  (W).  This  is  to  prevent 
any  heat  reaching  the  inner  cylinder  from  without.  A  weighed  quantity  of  the 
substance  (c)  to  be  investigated,  is  placed  in  the  combustion  chamber.  When 
combustion  is  ended,  during  which  the  inner  water  must  be  repeatedly 
stirred,  the  temperature  of  the  water  is  ascertained  by  means  of  a  delicate 
thermometer.  If  the  increase  of  the  temperature  and  the  amount  of  water  are 
known,  then  it  is  easy  to  calculate  the  number  of  heat-units  producecl  by  the 
combustion  of  a  known  weight  of  the  substance  (see  Introduction). 

The  ice-calorimeter  may  also  be  used.  The  inner  cylinder  is  filled  with  ice 
and  not  with  water,  and  ice  is  also  placed  in  the  outer  cylinder  to  prevent  any 
heat  from  without  from  acting  upon  the  inner  ice.  The  heat  given  off  from  the 
combustion  chamber  causes  a  certain  amount  of  the  ice  to  melt,  and  the  water 
thereby  produced  is  collected  and  measured.  It  requires  79  heat-units  to  melt 
1  grm.  of  ice  to  1  grm.  of  water  at  0°C. 

Just  as  in  a  calorimeter,  although  much  more  slowly,  the  food-stuflfs 
within  our  body  are  burned  up,  oxygen  being  supplied,  and  thus 
potential  energy  is  transformed  into  kinetic  energy,  which,  in  the  case 
of  a  person  at  rest — i.e.,  when  the  muscles  are  inactive,  almost  completely 
appears  in  the  form  of  heat  (see  Introduction). 

Favre,  Silbermann,  Frankland,  Rechenberg,  B.  Danilewsky,  and  others  have 
made  calorimetric  experiments  on  the  heat  produced  by  food.  Thus,  there  are 
produced  by 

1  grm.  Albumin  4,998  heat-units 
1     ,,     Ox-flesh    5,103        „ 


I  grm.  Albumin  4,263 
1     ,,     Ox-flesh  4,368 


/  Completely  dried  and  completely 
\     burned. 

rWhen  burned  to  urea  {i.e.,  the  heat-units 
J  corresponding  to  the  urea  (1  grm. —2,206 
J  calories)  is  deducted  from  those  of  the 
I      albumin  and  flesh. 


1  gramme  of  the  following  dry  substances  yields  heat-units 


Casein,     .  . 
Potatoes, 

Milk,  .     .  . 

Bread,      .  . 

Rice,  .     .  . 

Starch,    .  . 
Yelk  of  egg. 

Alcohol,  .  . 

Stearin,  .  , 


5,785 
3,752 
5,093 
3,984 
3,813 
4,479 
6,460 
8,958 
9,036 


Palmitin,  .  .  . 
Olein,  .... 
Glycerin,  .  .  . 
Leucin,  .... 
Creatin,  .  .  . 
Grape-sugar,  . 
Cane-sugar,  .  . 
Milk-sugar,  .  . 
Vegetable  fibrin, . 


8,883 
8,958 
4,179 
6,141 
4,118 
3,939 
4,173 
4,162 
6,231 


Glutin,    .    . 
Legumin, 
Blood  fibrin. 
Peptone, 
Glutin,    .     . 
Chondrin,    . 
Flesh  extract 
(Liebig), 


6,141 
5,573 
5,709 
4,914 
5,493 
4,909 

3,206 


424  CHEMICAL   SOURCES    OF  HEAT. 

When  we  know  the  weight  of  any  of  the  above-named  substances 
consumed  by  a  man  in  twenty-four  hours,  a  simple  calculation  enables 
us  to  determine  how  many  heat-units  are  formed  in  the  body  by 
oxidation — i.e.,  provided  the  substance  is  completely  oxidised. 

Sources  of  Heat. — The  individual  sources  of  heat  are  to  be  found  in 
the  following : — 

(1.)  In  the  transformation  of  the  chemical  constituents  of  the  food, 
endowed  with  a  large  amount  of  potential  energy,  into  such  substances 
as  have  little  or  no  energy. 

The  organic  substances  used  as  food  consist  of  C,  H,  0,  N,  so  that  there 
takes  place — (a)  Combustion  of  C  into  COg,  of  H  into  HgO,  whereby  heat 
is  produced;  1  grm.  C  burned  to  produce  COg  yields  8,080  heat-units, 
while  1  grm.  H  oxidised  to  HgO  yields  34,460  heat-units.  The  0  neces- 
sary for  these  processes  is  absorbed  during  respiration,  so  that,  to  a  cer- 
tain extent  at  least,  the  amount  of  heat  produced  may  be  estimated  from 
the  amount  of  0  consumed.  The  same  consumption  of  0  gives  rise 
to  the  same  amount  of  heat  whether  it  is  used  to  oxidise  H  or  0 
(Pfliiger).  There  is  a  relation  amounting  to  cause  and  effect,  between 
the  amount  of  heat  produced  in  the  body  and  the  0  consumed.  The 
cold-blooded  animals,  which  consume  little  O  have  a  low  temperature ; 
amongst  warm-blooded  animals,  1  kilo,  of  a  living  rabbit  takes  up 
within  an  hour  0*914  grm.  0,  and  its  body  is  heated  to  a  mean  of 
38°C.  1  kilo,  of  a  living  fowl  uses  1"186  grms.  0,  and  gives  a  mean 
temperature  of  43"9°C.  (Regnault  and  Eeiset).  The  amount  of  heat 
produced  is  the  same  whether  the  combustion  occurs  slowly  or  quickly; 
the  rapidity  of  the  metabolism,  therefore,  affects  the  rapidity,  but  not 
the  absolute  amount  of  heat  production.  The  combustion  of  inorganic 
substances  in  the  body,  such  as  the  sulphur  into  sulphuric  acid,  the 
phosphorus  into  phosphoric  acid,  is  another,  although  very  small,  source 
of  heat. 

(&.)  In  addition  to  the  processes  of  combustion  or  oxidation,  all 
those  chemical  'processes  in  our  body,  by  which  the  amount  of  the  avail- 
able potential  energy  which  is  present  is  diminished,  in  consequence  of 
a  greater  satisfaction  of  atomic  affinities,  lead  to  the  production  of 
heat.  In  all  cases  where  the  atoms  assume  more  stable  positions  with 
their  affinities  satisfied,  chemical  energy  passes  into  kinetic  thermal 
energy,  as  in  the  alcoholic  fermentation  of  grape-sugar,  and  other 
similar  processes. 

Heat  is  also  developed  during  the  following  cliemical  processes  : — 
(a)  During  the  union  of  bases  with  acids  (Andrews).  The  nature  of  the  base 
determines  the  amount  of  heat  produced,  while  the  nature  of  the  acid  is  without 
effect.  Only  in  those  cases  where  the  acid,  e.g.,  CO2,  is  unable  to  set  aside  the 
alkaline  reaction,  the  amount  of  heat  produced  is  less.  The  formation  of  com- 
pounds of  chlorine  (e.g.,  in  the  stomach)  produces  heat. 


PHYSICAL  SOURCES   OF  HEAT.  425 

(/3)  When  a  neutral  salt  is  changed  into  a  basic  one  (Andrews).  In  the  blood,  the 
sulphuric  and  phosphoric  acids  derived  from  the  combustion  of  S  and  P  are  united 
with  the  alkalies  of  the  blood  to  form  basic  salts.  The  decomposition  of  the  car- 
bonates of  the  blood  by  lactic  and  phosphoric  acids  forms  a  double  source  of  heat, 
on  the  one  hand,  by  the  formation  of  a  new  salt,  as  well  as  by  the  liberation 
of  COo,  which  is  partly  absorbed  by  the  blood. 

(y)  The  combination  of  htemoglobin  with  0  (§  36). 

In  connection  with  those  chemical  processes,  whereby  the  heat  of 
the  body  is  produced,  heat-absorbing  intermediate  compounds  are 
not  unfrequently  formed.  Thus,  in  order  that  the  final  stage  of  more 
complete  saturation  of  the  affinities  be  reached,  intermediary  atomic 
groups  are  formed,  whereby  heat  is  absorbed.  Heat  is  also  absorbed 
when  the  solid  aggregate  condition  is  dissolved  during  retrogressive 
processes.  But  these  intermediary  processes  whereby  heat  is  lost,  are 
very  small,  compared  with  the  amount  of  heat  liberated  when  the 
end-products  are  formed. 

(2.)  Certain  physical  processes  are  a  second  source  of  heat. 

(a)  The  transformation  of  the  I'metic  mechanical  energy  of  internal 
organs,  when  the  work  done  is  not  transferred  outside  the  body,  pro- 
duces heat.  Thus  the  whole  of  the  kinetic  energy  of  the  heart  is 
changed  into  heat,  owing  to  the  obstructions  which  are  opposed  to  the 
blood-stream.  The  same  is  true  of  the  mechanical  energy  evolved  by 
many  muscular  viscera.  The  torsion  of  the  costal  cartilages,  the  friction 
of  the  current  of  air  in  the  respiratory  organs,  and  the  ingesta  in 
the  digestive  tract,  all  yield  heat. 

An  excessively  minute  amount  of  the  mechanical  energy  of  the  heart  is  trans- 
ferred to  surrounding  bodies  by  the  cardiac  impulse  and  the  superficial  pulse-beats, 
but  this  is  infinitesimally  small.  During  respiration,  when  the  respiratory  gases 
and  other  substances  are  expired,  a  very  small  amount  of  energy  disappears 
externally,  which  does  not  become  changed  into  heat.  If  we  assume  that  the  daily 
work  of  the  circulation  exceeds  86,000  kilogram-meti'es,  the  heat  evolved  is  equal  to 
204,000  calories,  in  24  hours  (§  93),  which  is  sufficient  to  raise  the  temperature  of  a 
person  of  medium  size,  2°C.  In  former  times,  Boerhave  and  others  thought  that 
the  heat  of  the  body  was  chiefly  due  to  the  friction  of  the  blood  within  the 
vessels. 

(5)  When,  owing  to  muscular  activity,  the  body  produces  work  which 
is  transferred  to  external  objects,  e.g.,  when  a  man  ascends  a  tow^er  or 
mountain,  or  throws  a  heavy  weight,  a  portion  of  the  kinetic  energy 
passes  into  heat,  owing  to  friction  of  the  muscles,  tendons,  and  the 
articular  surfaces,  as  well  as  to  the  shock  and  pressure  of  the  ends  of 
the  bones  against  each  other. 

(c)  The  electrical  currents  which  occur  in  muscles,  nerves,  and  glands, 
very  probably  are  changed  into  heat.  The  chemical  processes  w^hich 
produce  heat  evolve  electricity,  which  is  also  changed  into  heat.  This 
source  of  heat,  however,  is  very  small. 


426  HOMOIOTHERMAL  AND   POIKILOTHERMAL  ANIMALS. 

{d)  Other  processes  are  the  formation  of  heat  from  the  absorption  of  COj 
(Henry),  by  the  concentration  of  water  as  it  passes  through  membranes  (Regnault 
and  Pouillet),  in  imbibition  (Matteucci,  1834),  formation  of  solids— e.g.,  of  chalk 
in  the  bones.  After  death,  and  in  some  pathological  processes  during  life,  the 
coagulation  of  blood  (Valentin,  Schiffer),  and  the  production  of  rigor  mortis,  are 
sources  of  heat, 

207.  Homoiothermal  and  Poikilothermal  Animals. 

In  place  of  the  old  classification  of  animals  into  '•  cold-blooded  "  and 
"  warm-blooded,"  another  basis  of  classification  seems  desirable,  viz.,  the 
relation  of  the  temperature  of  the  body  to  the  temperature  of  the 
surrounding  medium. 

Bergmann  introduced  the  word  homoiothermal  animals  for  the 
warm-blooded  animals  (mammals  and  birds),  because  these  animals  can 
maintain  a  very  uniform  temperature,  even  although  the  surrounding 
temperature  be  subject  to  considerable  variations.  The  so-called  cold- 
blooded animals  are  called  poikilothermal,  because  the  temperature  of 
their  bodies  rises  or  falls,  within  wide  limits,  with  the  heat  of  the 
surrounding  medium. 

When  homoiothermal  animals  are  kept  for  a  long  time  in  a  cold 
medium,  their  heat  production  is  increased,  and  when  they  are  kept  for 
a  long  time  in  a  warm  medium  it  is  diminished. 

Fordyce  gave  a  proof  of  the  nearly  uniform  temperature  in  man.  A  man  re- 
mained ten  minutes  in  an  oven  containing  very  dry  hot  air,  and  yet  the  tempera- 
ture of  the  pahn  of  his  hand,  mouth,  and  urine  was  increased  only  a  few  tenths  of 
a  degree. 

Becquerel  and  Brechet  investigated  the  temperature  of  the  human  biceps  (by 
means  of  thermo-electric  needles),  when  the  arm  had  been  one  hour  in  ice,  and 
yet  the  temperature  of  the  muscular  tissue  was  cooled  only  0  •2°C.  The  same 
muscle  did  not  undergo  any  increase  in  temperature,  or  at  most  0'2°C,  when  the 
man's  arm  was  placed  for  a  quarter  of  an  hour  in  water  at  42°C. 

If  heat  be  rapidly  abstracted  or  rapidly  supplied  to  the  body,  so  as 
to  produce  rapid  variation  of  the  temperature,  life  is  endangered. 

Poikilothermal  animals  behave  very  differently;  the  temperature  of 
their  bodies  generally  follows,  although  with  considerable  variations, 
the  temperature  of  the  surroundings.  When  the  temperature  of  the 
surroundings  is  increased,  the  amount  of  heat  produced  is  increased,  and 
when  the  surrounding  temperature  falls,  the  amount  of  heat  evolved 
within  the  body  also  falls. 

The  following  table  shows  very  clearly  the  characters  of  poikilothermal 
animals,  e.g.,  frogs  (Rana  Esculenta),  which  were  placed  in  air  and  water 
of  varying  temperatures.  The  frogs  were  fixed  to  an  iron  support,  and 
immersed  up  to  the  mouth.  The  temperature  was  measured  by  means 
of  a  thermometer  introduced  through  the  mouth  into  the  stomach. 


THERMOMETRY. 


427 


In  Water.                    | 

Temperature  of  the 

Temperature  of  Frog's 

Water. 

Stomach. 

41-0°  C. 

38  0°  C. 

35-2 

34-3 

300 

29-6 

23  0 

22-6 

20-6 

20-7 

11-5 

12-9 

5-9 

8-0 

2-8 

5-3 

In  Air. 


Temperature  of  the 

Temperature  of  Frog's 

Air. 

Stomach. 

40-4°  C. 

31-7°  C. 

35-8 

24  "2 

27-4 

19  ■7 

19  8 

15-6 

16-4 

14-6 

14-7 

10-2 

6-2 

7-6 

5-9 

8-6 

Temperature  of  different  Animals.— -Sirrf.s— Gull,  37  8°;  swallow,  44-03°. 

Mammals — Dolphin,  35 '5°;  mouse,  41*1°.  Reptiles — Snakes,  10°-12°,  but  higher 
when  incubating.  Amphibians  and  fishes — 0"5°-3°  above  the  tempei-ature  of  the 
surroundings.  Arthropoda — 0*l°-5'8°  above  the  surroundmgs.  Bees  in  a  hive, 
30°-32°,  and  when  swarming,  40°.  The  foUowmg  animals  have  a  temperature  higher 
than  the  surrounding  temperatiu'e: — Cephalopods,  0"57° ;  molluscs,  0'46°;  echino- 
<ierms,  0-40°  ;  medusa?,  0-27°  ;  polyps,  0-21°C. 

208.  Methods  of  Estimating  Temperature— 
Thermometry. 

Thermometry. — By  using  thermometric  apparatus,  we  are  enabled  to  obtain 
information  regarding  the  degree  of  heat  of  the  body  to  be  investigated.  For  this 
})urpose,  the  following  methods  are  employed : — 

A.  The  Thermometer  (Galileo,  1603).  — Sanctorius  made  the  first  ther- 
mometric observations  on  man  (1626).  Celsius  (1701-1744)  divided  his  ther- 
mometer into  1(K)  parts,  and  each  part  was  again  divided  into  10  parts,  so 
that  iV°C.  could  be  easily  read  off.  All  thermometers  which  have  been  used  for 
a  long  time  give  too  high  readings  (Bellani),  hence  they  should  be  compared,  from 
tune  to  time,  with  a  normal  thermometer.  When  taking  the  temperature,  the 
bulbs  ought  to  be  surromided  for  15  minutes,  and  dm-ing  the  last  5  minutes  the 
mercury  column  ought  not  to  vary.  A  very  sensitive  thermometer  will  indicate 
the  temperature  after  7  seconds  if  the  urine-stream  be  directed  upon  its  bulb 
(Oertmann).  Minimal  and  maximal  thermometers  are  often  of  use  to  the 
physician. 

Walferdhi's  metastatic  thermometer  (Fig.  167)  is  specially  useful  for  comparative 
observation.  The  tube  is  very  narrow  in  comparison  with  the  bulb,  and  in  order 
that  the  stem  be  not  too  long,  it  is  constructed  so  that  the  amount  of  mercury  can 
be  varied.  A  quantity  of  mercuiy  is  taken,  so  that  with  the  temperature  expected 
the  thread  of  mercury  will  stand  about  the  middle  of  the  stem.  A  small  bulb  at 
the  upper  part  of  the  stem  receives  the  excess  of  Hg.  Suppose  a  temperature 
between  37°-40°C.  is  to  be  measured,  the  bulb  is  first  heated  a  little  over  40°C.,  it 
is  then  suddenly  cooled,  and  shaken  at  the  same  tune,  so  that  the  thread  of  mercury 
is  thereby  suddenly  broken  above  40°.  The  tube  is  so  narrow  that  1°C.  is  equal  to 
about  10  centimetres  of  the  length  of  the  tube,  so  that  i-oTy°C.  is  still  1  millimetre 
in  length.  The  scale  is  divided  empirically,  but  the  value  of  the  divisions  must  be 
compared  with  a  normal  thermometer.  llilUll 

Kronecker  and  Meyer  used  very  small  maximal  "  outflow  thermometers  ''  (Dulong         \^/ 
and  Petit),  and  caused  them  to  pass  through  the  intestinal  canal,  or  through  large     Fig-  167. 
blood-vessels.     The  mercury  flows  out  of  the  short  open  tube,  and  of  com-se  more  Walferdin's 
flows   out  the  higher  the  temperature.      After   these   small  bulbs  have  passed   Metastatic 
through  the  animal,  a  compai-ison  is  instituted  with  a  normal  thermometer  to     Thermo- 
determine  at  what  temperature  the  mercury  reaches  the  free  margin  of  the  tube.  meter. 


f 


428 


THERMO-ELECTRIC   MEASUREMENT   OF  HEAT. 


nl     4 


M 


Fig.  168. 
Scheme  of  thermo-electric  arrangements  for  estimating  the  temperature. 

B.  Thermo-electric  Method, — This  method  enables  us  to  determine  the 
temperature  accurately  and  rapidly  (Fig.  168, 1).  The  thermo-electric  galvanometer 
of  Meissner?'and|Meyerstein  consists  of  a  circular  magnet  (m),  suspended  by  a 
thread  of  silk  (c),  to^which  a  small  mirror  (S)  is  attached.  A  large  stationary 
bar  magnet  (M)  is  placed  near  the  magnet  (m),  so  that  the  north  poles  (n  and  N) 
of  both  magnets  point  in  the  same  direction,  and  it  is  so  arranged  that  tlie  sus- 
pended magnet  is  caused  to  point  to  the  north  by  a  minimal  action  of  M. 

A  thick  copper  wire  (b,  i)  is  coiled  several  times  round  m  (although  in  the  Fig. 
it  is  represented  as  a  single  coil),  and  the  ends  of  the  wire  are  soldered  to  two 
thermo-elementSj'each  composed  of  two  different  metals — iron  and  German  silver, 
the  two  similar  free  elements  being  united  by  a  wire  (bi),  so  that  the  two  thermo- 
elements form  part  of  a  closed  circuit.  A  horizontal  scale  (K,  K)  is  placed  at  a 
distance  of  3  metres  from  the  mirror,  so  that  the  divisions  of  the  scale  are  seen  in 
the  mirror.  The  scale  itself  rests  upon  a  telescope  (F)  directed  towards  the  mirror. 
The  observer  (B)  who  looks  through  the  telescope  can  see  the  divisions  of  the  scale 


T'HERMO-ELECTRIC   NEEDLES,  42d 

in  the  mirror.  When  the  magnet,  and  with  it  the  mirror,  swing  out  of  the  mag- 
netic meridian,  the  observer  notices  other  divisions  of  the  scale  in  the  mirror. 
When  one  of  the  thermo-elements  is  heated,  an  electrical  current  is  produced, 
which  passes  from  the  iron  to  the  German  silver  in  the  heated  couple,  and  causes 
a  deviation  of  the  suspended  magnet.  Suppose  a  person  were  swimming  in  the  direc- 
tion of  the  current  in  the  conducting  wire,  then  the  north  pole  of  the  magnet  goes 
to  the  north  (Ampere).  The  tangent  of  the  angle  <j>,  through  which  the  freely 
moveable  magnet  is  diverted  by  a  galvanic  current,  from  its  position  of  rest  or  zero, 
in  the  magnetic  meridian,  is  the  same  as  the  galvanic  stream ;  G  is  proportional  to  the 

magnetic  energy  D,  i.e.,  tang.  ^  =  f).     If  G  is  to  remain  the  same,  and  the  tang.  0  to 

be  as  large  as  possible,  the  magnetic  energy  must  be  diminished  as  much  as  possible. 
If  the  magnetism  of  the  suspended  magnet  be  indicated  by  m,  and  that  of  the 
earth  by  T,  the  magnetic  directing  energy  D  =  T)k,  so  that  D  can  be  diminished  in 
two  ways:  (1)  by  diminishing  the  magnetic  moment  of  the  suspended  magnet,  as 
may  be  done  by  using  a  pair  of  astatic  needles,  such  as  are  used  in  Nobili's  galvan- 
ometer; (2)  and  also  by  weakening  the  magnetism  of  the  earth,  by  placing  an 
accessory  stationary  magnet  (Hauy's  rod)  in  the  same  direction,  and  near  the  sus- 
pended magnet.  An  important  arrangement  for  rapidly  getting  the  magnet  to 
zero  is  the  dead-beat  arrangement  of  Gauss  (not  figured  in  the  scheme). 

It  consists  of  a  thick  copper  cylinder,  on  which  the  wire  of  the  coil  is  wound. 
This  mass  of  copper  may  be  regarded  as  a  closed  multiplicator  with  a  very  lai-ge 
transverse  section.  The  vibrating  magnet  indiices  a  current  of  electricity  in  this 
closed  circuit,  whose  intensity  is  greatest  when  the  velocity  of  the  excursion  of 
the  magnet  is  greatest,  and  which  takes  the  opposite  direction  as  soon  as  the 
magnet  returns  towards  zero.  These  induced  currents  cause  a  dimtaution  of  the 
vibrations  of  the  magnet  in  this  way,  that  the  arc  of  vibration  of  the  magnet 
diminishes  very  rapidly,  almost  in  a  geometrical  progression.  The  induced 
damping-current  is  stronger,  the  less  the  resistance  in  the  closed  circuit,  and  in 
the  damper  or  dead-beat  arrangement  itself,  the  greater  the  section  of  the  copper 
ring.  This  damping  arrangement  limits  the  oscillations  of  the  magnet,  and  it 
comes  to  rest  rapidly  and  promptly  after  3  or  4  small  vibrations,  so  that  much  time 
is  saved.  The  angle  of  deviation  is  so  small  that  the  angle  itself  may  be  taken 
instead  of  the  tangent. 

The  thermo-electric  needles  of  Dutrochet  (II)  may  be  placed  in  the  circuit. 
They  consist  of  iron  and  German  silver  soldered  at  their  points ;  or  the  needles  of 
Becquerel  (III)  may  be  used.  They  consist  of  the  same  metals  soldered  in  a  straight 
line,  one  behind  the  other.  The  needles  must  always  be  covered  by  a  varnish, 
which  will  prevent  the  parenchymatous  juices  from  acting  upon  them,  and  so 
causing  a  current.  Before  the  experiment  we  must  determine  what  extent  of 
excursion  on  the  scale  is  obtained  with  a  certain  temperature.  In  order  to  deter- 
mine this,  a  delicate  thermometer  is  fixed  to  each  of  the  thermo-couples,  and  both 
are  placed  in  oil  baths,  which  differ  m  temperature — say  by  1°C. — as  can  be 
determined  by  the  thermometers.  When  the  current  is  closed,  the  excursion  ou 
the  scale  will  indicate  1°C.  Suppose  that  the  excursion  was  150  mm.,  then  each 
mm.  of  the  scale  would  be  equal  to  i3Tr°C.  When  this  is  determined,  the  two 
thermo-needles  may  be  placed  in  the  different  tissues  or  organs  of  animals,  and, 
of  course,  we  obtain  the  difference  of  temperature  in  these  places.  Or  one 
thermo-couple  may  be  placed  in  a  bath  of  constant  temperature  (nearly  that  of  the 
body),  in  which  is  placed  a  delicate  thermometer,  while  the  other  needle  is  intro- 
duced into  the  organ  to  be  investigated.  In  this  case,  we  obtain  the  difference  of 
temperature  between  the  tissue  and  the  source  of  the  constant  heat.  The  electric 
current  passes  in  the  warmer  needle  from  the  iron  to  the  German  silver,  and  thus 
through  the  wires  of  the  apparatus.  For  small  diff'erences  of  temperature,  such 
as  occur  in  the  body,  the  thermo-electric  energy  is  always  proportional  to  the 


430  TEMPERATURE  TOPOGRAPHY. 

difference  of  temperature  of  the  two  needles  or  couples.  In  place  of  a  single  pair 
of  needles  several  may  be  used,  whereby  the  sensitiveness  of  the  apparatus  is 
greatly  increased.  Helmholtz  found  that  by  using  16  antimony-bismuth  couples, 
he  could  detect  an  increase  of  Twin>°G.  Schiffer  prepared  a  simple  thermopile 
(IV)  by  soldermg  together  alternately  four  pairs  of  wires  of  iron  (/)  and  German 
silver  (a).  These  are  placed  in  the  two  organs  (A  and  B),  which  are  to  be 
investigated,  whereby  a  very  high  degree  of  exactness  is  obtained. 


209.  Temperature  Topography. 

Although  the  blood,  in  virtue  of  its  continual  motion,  completing, 
as  it  does,  the  circulation  in  23  seconds,  must  exercise  a  very  consider- 
able influence  on  the  equilibration  of  the  temperature  in  different 
organs,  nevertheless  a  completely  uniform  temperature  does  not  exist, 
and  the  temperature  varies  in  different  parts: — 


1.  Temperature  of  the  Skin.— 

Middle  of  the  sole  of  the  foot,         .      32-26°C. 


Near  tendo  achillis. 
Anterior  surface  of  leg, 
Middle  of  calf. 
Bend  of  knee. 
Middle  of  upper  arm, 
Inguinal  fold, 
Near  cardiac  impulse. 


33 '85  I  J.  Davy  made  these  observations 
33  "05  I  directly  after  standing,  while 
33  "85  V  naked,  with  the  temperature 
35-00  /  of  the  room  at  21°C.  Only  the 
34'40  I  under  surface  of  the  ther- 
35*80  I  mometer  touched  the  skin. 
34-40      J 

In  the  closed  axilla,  36-49  (mean  of  505  individuals); — 36-5  to  37-25  (Wunderlich); 
— 36-89°C  (Liebermeister). 


The  temperature  of  the  skin  of  the  head  is  higher  in  the  region  of  the  forehead 
and  parietal  region  than  in  the  occipital  region;  the  left  side  is  warmer  than  the 
right  (Maragliano).  Dyspnoea  increases  the  temperature  of  the  skin  (Heidenhain, 
Frankel). 

Method. — Liebermeister  determines  the  temperature  of  free  cutaneous  surfaces 
thus:— The  bulb  of  the  thermometer  is  heated  slightly  above  the  temperature 
expected;  after  the  mercury  begins  to  fall,  the  bulb  is  placed  on  the  skm,  and  if 
the  bulb  has  the  same  temperature  as  the  skin,  the  mercury  remains  stationary. 
This  experiment  must  be  repeated  several  times. 

2.  Temperature  of  the  Cavities. — 

Mouth  under  the  tongue,      ......         37'19°0. 

Eectum, 38-01 

Vagina,         .........         38*30 

(Uterine  cavity  somewhat  warmer;  cervical  canal  somewhat  cooler. ) 
Urine, 37*03 

The  temperature  falls  in  the  stomach  during  digestion  (p.  332). 
Cold  injections  (11°C.)  into  the  rectum  rapidly  lowe  rthe  temperature 
in  the  stomach  1°C.  (Winternitz). 

3.  The  Temperature  of  the  Blood  is,  as  a  mean,  39°C.  The  venous 
blood  in  internal  viscera  is  warmer  than  the  arterial,  but  it  is  cooler  in 
peripheral  parts: — 


TEMPERATURE   OF   THE  BLOOD   AND   TISSUES.  431 


Blood  of  the  right  heart,    .... 

^^^\       »        •        •         •        •        ^^"S     ^  CI.  Bernard. 
,,         aorta,     ..... 

,,         hepatic  veins, 


,,         superior  vena  cava, 

inferior  ,,  .  •         38-11    ^  v.  Liebig. 

,,         crural  vem, 

The  lower  temperature  of  the  blood  in  the  left  heart  may  be  explained  by  the 
blood  becoming  cooled  in  its  passage  through  the  lungs  during  respiration. 
According  to  Heidenham  and  Korner,  the  right  heart  is  slightly  warmer  because 
it  lies  in  relation  with  the  warm  liver,  whilst  the  left  heart  is  surrounded  by  the 
lung  which  contains  air.  This  obsei-vation  of  Malgaigne  (1832),  Berger,  and 
G.  V.  Liebig  is  disputed  by  others,  who  say  that  the  left  heart  is  slightly  warmer 
(Jacobson  and  Bernhardt)  because  the  combustion  processes  are  more  active  m 
arterial  blood,  and  heat  is  evolved  during  the  formation  of  oxyhajmoglobin 
(Gamgee).  The  blood  in  the  veins  is  usually  cooler  than  in  the  corresponding 
arteries  (Haller),  owing  to  the  superficial  position  of  the  former,  whereby  they 
give  off  heat  during  their  long  course;  thus  the  blood  of  the  jugular  vein  is  ^  to 
2°C.  lower  than  the  blood  in  the  carotid  (Colin);  the  crural  vein  |-1°  cooler  than  in 
tlie  crural  artery  (Becquerel  and  Erechet).  Superjlcial  veins,  more  especially  those 
of  the  skin,  give  off  much  heat,  and  their  blood  is,  therefore,  somewhat  cooler. 
The  warmest  blood  is  that  of  the  hepatic  vein,  39'7°C.  (CI.  Bernard),  partly  owing 
to  the  great  chemical  changes  which  occur  within  the  liver  (p.  432),  and  partly 
to  its  protected  situation.  By  means  of  small  outflow  thermometers  introduced 
into  the  circulation,  Kronecker  and  Meyer  found  the  following  temperatures  in 
three  starving  dogs:— Vena  azygos,  37-7  (38  0)  (39-0);  right  ventricle,  38-3  (39-2) 
(39-2);  branch  of  the  pulmonary  artery,  38-4  (38-6)  (40-2).  At  the  same  time,  the 
temperature  in  the  stomach  was  38*6  (37*3)  (40-0),  and  m  the  rectum,  39*5  (39-5) 
(39*4);  the  maximum  temperature  in  the  last  two  dogs  was  40"1  and  41  "25  hence 
in  the  starving  condition,  the  temperature  of  the  stomach  was  less  than  the 
temperature  of  the  blood  in  the  pulmonary  circulation. 

4.  Temperature  of  the  Tissues. — The  individual  tissues  are  warmer : 
(1)  the  greater  the  transformation  of  kinetic  energy  into  heat,  i.e.,  the 
greater  the  tissue  metabolism;  (2)  the  more  blood  they  contain;  (3) 
and  the  more  protected  their  situation.  According  to  Heidenhain  and 
Korner,  the  cerebrum  is  the  Avarmest  organ  in  the  body. 

Berger  measured  the  temperature  of  the  tissues  of  a  sheep,  and  found  the 
following: — 

While  the  temperature  was  in — 
Rectum,       .         .         .         40 '07 
Right  heart,         .         .         41-60 
Left  heart,  .         .         40-90 

Becquerel  and  Brechet  found  the  temperature  of  the  human  subcutaneous  tissue 
to  be  2-l°C.  lower  than  that  of  the  neighbouring  muscles.  The  horny  tissues  do 
not  produce  heat,  and  their  low  temperature  is  due  to  the  conduction  of  heat  from 
the  parts  on  which  they  grow.  The  temperature  of  the  cornea  partly  depends  on 
that  of  the  iris,  and  the  more  contracted  the  pupil  is,  it  receives  more  heat  from 
the  blood-vessels  of  the  iris. 


Subcutaneous  tissue. 

37-35 

Brain,     .         .         .         . 

40-25 

Liver,     .         .         .         . 

41-25 

Lungs,    .         .         .         , 

41-40 

432  CONDITIONS   INFLUENCING  TEMPERATtJRE   OF  ORGANS. 

210.  Conditions  influencing  the  Temperature 
of  Organs. 

The  temperature  of  the  individual  organs  is  by  no  means  constant; 
it  is  influenced  by  many  conditions;  amongst  these  are  the  following: — 

(1.)  The  more  heat  that  is  ])roduced  independently  within  a  j;ar^,  the 
higher  is  its  temperature.  As  the  amount  of  heat  produced  within  a  part 
depends  upon  its  metabolism,  therefore,  when  the  metabolism  is  in- 
creased, the  amount  of  heat  produced  is  similarly  increased. 

(a)  Glands  produce  more  heat  during  the  act  of  secretion,  as  is  proved 
by  the  higher  temperature  of  their  secretion,  or  by  the  higher  tempera- 
ture of  the  venous  Hood  flowing  out  of  their  veins.  Ludwig  found 
that  when  he  stimulated  the  chorda  tympani,  the  secretion  of  the  sub- 
maxillary gland  was  r5°C.  warmer  than  the  blood  in  the  carotid,  which 
supplied  the  gland  with  blood.  The  blood  in  the  renal  vein  in  a 
kidney  which  is  secreting  is  warmer  than  the  blood  in  the  renal  artery. 
The  secreting  liver  produces  much  heat.  CI.  Bernard  investigated  the 
temperature  of  the  blood  of  the  portal  and  hepatic  veins  during  hunger, 
at  the  beginning  of  digestion,  and  when  digestion  was  most  active,  and 
he  found : — 

Temperature  of  portal  vein,     .     37'8"C.  \  After  4  days    f   Blood  of  right  heart, 
„  hepatic   ,,       .     .S8"4      /     starvation.    \  38'8°. 

(Hunger  period. ) 

Temperatvire  of  portal  vein,     .     39"9       )    -d     ■     ■        t  n-      i.- 

hepatic,  .     39-5       (    Beginning  of  digestion. 

Temperature  of  portal  vein,     .     397       )  Digestion  most  /  Blood    of   right  heart 
,,  hepatic,  .     41*3       \  active.         [  diiring  digestion,  39  "2°. 

When  a  dog  receives  a  moderate  diet,  the  mean  temperature  in  the  stomach  is 
39°C. ,  in  the  rectum,  39"5°C. ;  at  the  end  of  the  first  day  of  hunger,  in  the  stomach, 
387°,  in  the  rectum,  39 '3°;  while  after  food,  in  both  situations  it  is  40°. 
Chemical  or  mechanical  stimulation  of  the  gastric  mucous  membrane,  or  even  the 
sight  of  food,  has  a  similar  action  (Kronecker  and  Meyer). 

(&)  When  the  muscles  contract  they  evolve  heat  (Bunsen,  1805). 
Davy  found  that  an  active  muscle  became  07°C.  warmer;  while 
Becquerel  (1835),  by  means  of  a  thermo-galvanometer,  found  that 
human  muscles,  when  kept  contracted  for  five  minutes,  became  1°C. 
warmer  (see  Physiology  of  Muscle). 

This  is  one  of  the  reasons  why  the  temperature  may  rise  above  40°  during 
rapid  running.  A  temperature  obtained  by  energetic  muscular  action  usually  does 
not  fall  to  the  normal  until  after  resting  for  14  hours  (Billroth).  The  low 
temperature  of  paralysed  limbs  depends  partly  upon  the  absence  of  the  muscular 
contractions. 

(c)  With  regard  to  the  effect  of  sensory  nerves  upon  the  tempera- 


CONDITIONS   INFLUENCING   THE   TEMPERATURE.  433 

ture,  one  of  the  first  points  to  ascertain  is  whether  the  circulation  is 
accelerated  or  retarded  by  their  stimulation,  or  whether  the  respiration 
is  increased  or  diminished  (§214,  II.,  3),  and  whether  the  muscles  of  the 
skeleton  are  relaxed  or  contracted  reflexly  (§214,  I.,  3).  In  the  former 
case,  the  temperature  of  the  interior  and  rectum  is  increased;  in  the 
latter,  diminished. 

That  there  are  heat-regulating  nerve-centres  has  not  been  definitely 
proved;  with  regard  to  the  influence  of  vaso-motor  nerves  see  vol.  ii. 

(d)  The  temperature  of  the  body  rises  during  mental  exertion.  Davy 
observed  an  increase  of  0"3°C.  after  vigorous  mental  exertion. 

Lombard  observed  that  the  temperature  of  the  forehead  rose  0"5°C.  during 
mental  activity  and  emotional  disturbances.  The  part  of  the  forehead  corre- 
sponded to  the  posterior  region  of  both  upper  frontal  convolutions,  to  the  anterior 
central  convolution,  and  (?)  to  the  anterior  part  of  the  posterior  central  convolu- 
tion.    The  temperature  was  higher  on  the  left  side. 

(e)  The  parenchymatous  fluids,  serous  fluids,  and  lymph  produce 
little  heat  owing  to  their  feeble  metabolism,  hence  they  have  the  same 
temperature  as  their  surroundings;  the  epidermal  and  horny  tissues 
do  not  produce  heat,  they  merely  conduct  it  from  subjacent  structures. 

(2.)  The  temperature  depends,  to  a  large  extent,  upon  the  amount  of 
blood  in  an  organ,  and  also  upon  the  rapidity  with  which  the  blood  is 
renewed  by  the  circulation.  This  is  best  observed  in  the  difierence  of 
the  temperature  between  a  cold  pale  bloodless  hand  and  a  warm  red 
congested  one. 

Becquerel  and  Brecliet  found,  that  the  temperature  of  the  human  biceps  fell 
several  tenths  of  a  degree,  when  the  axillary  artery  was  compressed.  Ligature  of 
the  iliac  artery  in  a  dog  caused  a  fall  of  \°C  within  18  minutes;  while  the 
removal  of  the  ligature  caused  the  temperature  to  rise  rapidly  to  normal.  Liga- 
ture of  the  crural  artery  and  vein  in  a  dog  causes  a  fall  of  several  degrees  (Landois). 
If  the  extremities  be  kept  suspended  in  the  air,  they  become  bloodless  and  cold. 

Liebermeister  has  pointed  out  a  difference  with  regard  to  the  external  and 
internal  parts  of  the  body.  The  external  partis  give  off  more  heat  than  they 
produce,  so  that  they  become  cooler  the  more  slowly  new  blood  flows  into  them, 
and  warmer  the  greater  the  rapidity  of  the  blood-stream  through  them.  Accelera- 
tion of  the  blood-stream,  therefore,  causes  the  temperature  of  peripheral  parts 
to  approximate  more  and  more  to  the  temperature  of  internal  organs,  while 
retardation  of  the  blood-stream  causes  them  to  approach  the  temperature  of  the 
surrounding  medium.  Exactly  the  reverse  is  the  case  with  internal  parts,  where 
a  large  amount  of  heat  is  produced,  and  heat  is  given  up  almost  alone  to  the 
blood  which  flows  through  them.  Their  temperature  must  fall  when  the  blood- 
stream through  them  is  accelerated,  and  it  is  raised  when  the  blood-stream  is 
retarded  (Heidenhain).  Hence  it  follows,  that  the  greater  the  difference  of  the 
temperature  between  peripheral  and  internal  parts,  the  slower  must  be  the 
velocity  of  the  circulation. 

(3.)  If  the  position  of  an  organ  be  such,  or  if  other  conditions 

28 


434 


ESTIMATION   OF  THE  AMOUNT  OF  HEAT. 


cause  it   to  give    off   heat  by  conduction  or  radiation,  then  its  tem- 
perature falls. 

A  good  example  of  this  is  the  skin,  which  varies  greatly  in  temperature  accord- 
ing to  the  temperature  of  the  surrounding  medium,  whether  it  is  covered  or 
uncovered,  whether  it  is  dry  or  moist  with  sweat  (which  abstracts  heat  when 
it  evaporates).  When  much  cold  food  or  drink  is  taken  the  stomach  is  cooled, 
and  when  ice-cold  air  is  breathed  the  respiratory  passages  as  far  as  the  bronchi 
are  cooled. 


211.  Estimation  of  the  Amount  of  Heat— 
Calorimetry. 

Calorimetry  is  the  method  of  determining  the  amount  of  heat 
possessed  by  any  body,  or  what  amount  of  heat  it  is  capable  of  pro- 
ducing. The  unit  of  measurement  is  the  "heat-unit,"  i.e.,  the  amount 
of  heat  (or  potential  energy)  required  to  raise  the  temperature  of  1 
gramme  of  water,  1°C.  (see  Introduction). 

Experiment  has  shown  that  equal  quantities  of  different  substances  require  very 
unequal  amounts  of  heat  to  raise  them  to  the  same  temperature,  e.g.,  1  kilo, 
water  requires  nine  times  as  much  heat  as  1  kilo,  iron  to  raise  it  to  the  same 
temperature.  In  the  human  body,  therefore,  which  is  composed  of  very  different 
substances,  unequal  amounts  of  heat  will  be  required  to  raise  them  all  to  the  same 
temperatiire.  The  same  amount  of  heat  transferred  to  two  different  substances 
will  raise  them  to  different  temperatures.  Hence,  bodies  of  different  temperatures 
may  contain  equal  amounts  of  heat.  The  amount  of  heat  required  to  raise  a 
definite  quantity  {e.g.,  1  gramme)  of  a  svibstance  to  a  certain  higher  degree  {e.g., 
VC.)  is  called  "specific  heat"  (Wilkie,  1780).  The  specific  heat  of  water  (which  of 
all  bodies  has  the  highest  specific  heat)  is  taken  as  —  1.  By  ''heat- capacity"  is 
meant,  that  property  of  bodies  in  virtue  of  which  they  must  absorb  a  given  amount 
of  heat  in  order  to  have  a  certain  temperature  (Crawford). 

Calorimetry  is  employed: — I.  To  determine  the  specific  heat  of  the 
different  organs  of  the  body. — Only  a  few  observations  have  been  made. 
The  mean  specific  heat  of  the  following  animal  parts  (water=l)  is: — 


Human  Blood  =  1-02        (?) 

Arterial    „  =  1'031       (?) 

Venous      „  =  0-892      (?) 

Cow's  Milk  =  0-992 

Human  Muscle  =  0-741 

Ox  „  =  0-787 


Compact  Bone 
Spongy       „ 
Fat-tissue 
Striped  Muscle 
Defibrinated  Blood 


The  specific  heat  of  the  human  body,  as  a  whole,  is  about  that  of 
an  equal  volume  of  water. 

Kopp  has  estimated  the  specific  heat  of  solids  and  fluids  by  the  following 
method  (Fig.  169) : — The  solid  to  be  investigated  is  broken  in  pieces  about  the  size 
of  a  pea,  and  placed  in  a  test-tube,  A,  with  thin  walls,  which  is  closed  above  with 
a  cork,  from  which  a  copper-wire  with  a  hook  on  it  projects.  The  test-tube  con- 
tains a  certain  quantity  of  fluid  which  does  not  dissolve  the  substance,  but  which 
lies  between  its  pieces  and  covers  it.    It  is  weighed  three  times  to  ascertain  the 


SPECIFIC   HEAT    OF  THE   BODY. 


435 


weight  (1)  of  the  empty  glass,  (2)  after  it  is  lilled  with  the  solid  substance,  (3) 
after  the  fluid  is  added,  so  that  we  obtain  the  weight  of  the  solid  substance,  m, 
and  that  of  the  fluid,  f.  The  test-tube  and  its  contents  are  placed  in  a  mercury 
bath,  BB,  and  this  again  in  an  oil  hath,  C  C,  and  the  whole  is  raised  to  a  high 
temperature.  Into  BB  there  is  introduced  a  fine  thermometer,  T.  When  the 
tube,  A,  has  reached  the  necessary  temperature  (say  40°)  it  is  rapidly  placed  in 
the  water  of  the  accompanying  calorimeter-box,  D  D.  The  water  in  this  box, 
which  also  contains  a  thermometer,  D,  is  kept  in  motion  until  it  has  completely 


D 


liiiiiiiiTiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiil 
Fig.  169. 
Kopp's  apparatus  for  the  estimation  of  specific  heat. 


absorbed  all  the  heat  given  off  by  A.  Let  T  represent  the  temperature  to  which 
A  and  its  contents  were  raised  in  the  mercury  bath,  and  Ti  the  temperature  to 
which  it  fell  in  the  calorimeter;  let  s  be  the  specific  heat,  and  m  the  weight  of  the 
solid  substance  in  the  test-tube,  while  o-  and  n  represent  the  specific  heat  of  the 
weight  of  the  interstitial  fluid  in  the  test-tube;  and  lastly,  let  w  equal  the  amount 
of  water  in  contact  with  A,  which  absorbs  and  gives  off  heat;  then  W  represents 
the  amount  of  heat  which  the  test-tube  and  its  contents  give  ofi"  during  cooling, 

W  =  (s.  m  +  10  +  a-.  ^)   (T  -  Ti). 

The  amount  of  heat,  Wi,  absorbed  by  the  calorimeter  is 

where  M  represents  the  amount  of  water  in  the  calorimeter,  and  t  the  original 
temperature  of  the  water  in  the  calorimeter,  and  ti  the  temperature  to  which  it  is 
raised  by  placing  A  in  it.     If  W  and  Wj  are  equal,  then 

T^e  .pecijic  kea,  s  =  ^  ('<-')^^^^_<'^.UT -1,) 

If  a  fluid  substance  is  placed  in  the  test-tube,  and  its  weight  =  m,  and  its 
specific  heat  =  s,  the  formula  for  the  specific  heat  of  the  fluid  to  be  investigated  is 

M  {ti-t)-w  (T-T,) 


m(T-Ti). 

This  is  a  subject  which  has  been  very  slightly  cultivated, 
investigations  used  an  ice-oalorimeter  (§  206). 


J,  Rosenthal  in  hig 


436  TtTRKVAT.    COXDUCnVTTT    OF    THE    TISSUES. 

IL  Calorimetry  is  more  important  for  determining  the  arrwurd  of 
heat  prodneed  in  a  gmn  time  by  the  body  as  a  whole,  or  by  its  rn- 

laevaaaec  asd  Laplace  nmde  iiie  £rsfe  calozimetiic  observatioiis  on  animal  s  in 
1783,  by  -inpsanR  of  an  ice-esdiRimetier ;  a  guinea-pig  melted  13  ozs.  of  ice  in  10 
boms:  Crawfoad,  asA.  afierwazdE  Dnlong  and  Bespretz  (1S24),  used  Rnrnford's 
■wafer-caiudiMefair,  -winch  is  CTmilar  to  tibe  one  already  described — ^riz..  of  Favre 
saA  SSaaBtsana.  Sn^l  simmfAK  axe  placed  in  the  inner  rhin-walled  copper 
ckamber  (KJ,  -idiii^  fe  p3a.oed  in  a  ■w-ater-bat'h  surroiinded  on  all  sides  by  some 
TMoaresOfdBd&w  TW&aaL  TVe  require  to  know  the  amonnt  of  -water,  and  its 
«»MTnal  tecapeakaxe.  Tfaa  mnnbex'  <rf  calories  is  obtained  from  the  increase  of  the 
teaDpecabne  a£  ilie  end  of  iiie  experiment,  ■vrMch  lasts  several  hotrrs.  The  air  is 
sb^^bA.  to  tibe  aninta]  iiiTOiigh  a  special  appara-tns  resembling  a  gasometer.  The 
smffasA  of  GO*  in  iiie  gases  enolved  is  estimated  cbemically. 

Acc<3rding  to  D^retz,  a  bitch  forms  14,610  heat-rmits  per  hour — 
ix^  393.000  in  24  honrs.  Other  things  being  equal,  a  man  seven 
tTTTiRR  hearier  than  this  would  produce  in  24  hours  about  2,7-50,000 
caloric.  Senator  found  that  a  dog  weighing  6,330  grms.  produced 
15.370  calories,  and  excreted  at  the  same  time  3,67  grms.  CO^.  The 
first  calorimetric  experiments  on  maTi  were  made  by  Scharling  (1849). 
liebenaeister  estimated  the  amount  of  heat  given  off  by  a  man  placed 
in  a  cold  bath,  which  was  surrounded  with  a  woollen  covering.  Leyden 
placed  a  lower  limb  in  the  calorimeter,  whereby  6,000  grms.  water  were 
raised  I'C.  in  an  hour.  If  we  assume  that  the  total  superficial  area 
of  the  body  is  fifoeen  times  greater  than  that  of  the  leg,  the  human 
hoAj  would  produce  2,376,000  calories  in  24  hours. 


212.  TtLermal  Conductivity  of  Animal  Tissues. 

The  ihg-mal  cjondnctivity  of  animal  tissues  is  of  special  interest  in  connection 
infli.  flie  ddn  and  siibcataneoiis  fatty  tissne.  The  fatty  layer  nnder  the  skin, 
mne  espee^Ify  in  iiie  -i^ale,  walrus,  and  seal,  forms  a  protective  covering, 
wbexidiy  tiie  earadnciian  of  heat  from  internal  organs  is  rendered  almost  impos- 
aUe.  TirFPcHgaiannB  tqfCB.  this  Subject,  however,  are  few.  Griess  (1870) 
aijjMiiijilgJ  to  estinmte  iiie  iiiennal  conductivity  by  heating  one  part  of  the  tissue, 
aid  dtafaaauimng  when  and  in  what  direction  pieces  of  wax  placed  on  the  tissue  to 
be  invtadigated  beg^i  to  melt.  He  investigated  -the  stomach  of  the  sheep,  the 
Uadder,  ddn,  hoail^  horn,  and  bones  of  an  ox,  deer's  horn,  ivory,  mother-of-pearl, 
sbdl  of  ]a]]0ti&  He  found  that  fibrous  tissues  conducted  heat  more  readily  in 
the  direciaaa  <rf  Iheir  fibres  than  at  right  angles  to  the  course  of  the  fibres. 
Tlfcpj  ifce  figure  obtslned  from  the  melted  wax  were  usually  eUipticaL  Landois 
haa  made  simiLar  observations,  and  he  finds  that  tissues  conduct  better  in  the 
dheeikm.  of .  their  fibres.  After  bones,  hlood-dot  was  the  best  conductor,  then 
£(Anred  epieesi,  liver,  cartilage,  tendon,  muscle,  elastic  tissue,  nail  and  hair, 
UoodleBB  skin,  gasiaic  mucous  membrane,  washed  fibrin.  It  is  specially  interest- 
ing to  note  lunr  mndi  better  f=khi  containing  hhod  in  its  blood-vessels  conducts 
compazed  tritii  Uoodl^  gkin.  Hence  little  heat  is  given  ofi'  from  a  bloodless 
ddn,  iddle  oong^ed  din  conducts  and  gives  oft  much  more  heat. 


VARIATIONS   OF  THE  MEAN  TEMPERATURE.  437 

Like  all  other  substances,  the  human  body  is  enlarged  by  heat.  A  man 
weighing  60  kilos.,  and  whose  temperature  is  raised  from  37°C.  to  40°C.,  is 
enlarged  about  62  cubic  centimetres.  Connective-tissue  (tendon)  is  extended  by 
heat,  while  elastic  tissue,  the  skin,  like  caoutchouc,  are  contracted  (Lombard  and 
Walton). 


213.  Variations  of  the  Mean  Temperature. 

(1.)  General  Climatic  and  Somatic  Influences. — In  the  tropics,  the 
mean  temperature  of  the  body  is  about  ^°C.  higher  than  in  temperate 
climates,  where  again  it  is  several  tenths  of  a  degree  warmer  than  in 
cold  climates  (J.  Davy) ;  but  this  has  recently  been  denied  by  Boileau 
and  Pinkerton.  This  difference  is  comparatively  trivial,  when  we 
remember  that  a  man  is  subjected  to  a  variation  of  over  40''C.  in  passing 
from  the  equator  to  the  poles.  Observations  on  more  than  4000  persons 
show  that  when  a  person  goes  from  a  warm  to  a  cold  climate,  his  tempera- 
ture is  but  slightly  diminished,  but  when  he  goes  from  a  cold  to  a 
warm  climate  his  temperature  rises  relatively  considerably  more.  In  the 
temperate  zone,  the  temperature  of  the  body  during  a  cold  ivinter  is  usually 
0'1-0"3°C.  lower  than  it  is  on  a  warm  summer  day.  The  elevation  of  a 
place  above  sea-level  has  no  obvious  effect  on  the  temperature  of  the 
body.  There  seems  to  be  no  difference  in  different  races,  nor  in  the 
seoxs,  other  conditions  being  the  same.  Persons  of  powerful  physique 
and  constitution  are  said  to  have  generally  a  slightly  higher  temperature, 
than  feeble,  weak,  anaemic  persons. 

(2.)  Influence  of  the  General  Metabolism. — As  the  formation  of 
heat  depends  upon  the  transformation  of  chemical  compoimds,  whose 
chief  final  products,  in  addition  to  H^O,  are  CO^  and  urea,  the  amount 
of  heat  formed  must  go  pari  pasu  with  the  amount  of  these  excreta. 
The  more  rapid  metabolism  which  sets  in  after  a  full  meal  causes  a  rise 
of  temperature  to  several  tenths  of  a  degree  ("  Digestion-fever").  As 
the  metaboHsm  is  much  diminished  during  hunger,  this  explains  why 
the  mean  temperature  in  a  fasting  man  is  36-6°,  while  it  is  37"17°  on 
ordinary  days  (Lichtenfels  and  Frohlich). 

Jilrgensen  also  found  that  the  temperature  fell  on  the  first  day  of  inanition, 
(although  there  was  a  temporary  rise  on  the  second  day).  In  experiments  made 
upon  starving  animals,  the  temperature  at  first  fell  rapidly,  then  remained  con- 
stant for  a  considerable  time,  while  during  the  last  days  it  fell  considerably. 
Schmidt  starved  a  cat— on  the  15th  day  the  temperature  was  38"6°;  on  the  16th, 
38-3°;  17th,  37-64°;  18th,  35-8°;  19th  (death)  =  33-0°.  Chossat  found  that  starving 
mammals  and  birds  had  a  temperature  16°C.  below  normal  on  the  day  of  theiii 
death. 

(3.)  Influence  of  Age. — Age  has  a  decided  effect  upon  the  tempera- 
ture of  the  body.     The  extent  of  the  general  metabolism  is  in  part  an 


438 


VARIATIONS   OF  THE   MEAN  TEMPERATURE. 


index  of  the  heat  of  the  body  at  different  ages,  but  it  is  possible  that 
other  unknown  influences  also  are  active. 


Age. 

Mean  Temperature  at 
the  Ordinary  Temp. 

Normal  Limits. 

Where  Measured. 

Newly-born, 

37-45T. 

37-35-37-55°C. 

Rectum. 

5-9    year, 

37-72 

37-87-37-62 

Mouth  and  Rectum. 

15-20      „ 

37-37 

36-12-38-1 

Axilla. 

21-30      „ 

37-22 

... 

>  J 

25-30     „ 

36-91 

)) 

31-40     „ 

37-1 

36-25-37-5 

,, 

41-50     „ 

36-87 

,, 

51-60      „ 

36-83 

)5 

80      „ 

37-46 

... 

Mouth. 

Newly-born  Animals  exhibit  peculiarities  owing  to  the  sudden 
change  in  their  conditions  of  existence.  Immediately  after  birth,  the 
infant  is  0-3°  warmer  than  the  vagina  of  the  mother,  viz.,  37-86°.  A 
short  time  after  birth,  the  temperature  falls  0*9°,  while  12-24  hours 
afterwards,  it  has  risen  to  the  normal  temperature  of  an  infant,  which 
is  37*45°.  Several  irregular  variations  occur  during  the  first  weeks 
of  life.  During  sleep,  the  temperature  of  an  infant  falls  0-34°  to  0*56°, 
Avhile  continued  crying  may  raise  it  several  tenths  of  a  degree. 
Old  people,  on  account  of  their  feeble  metabolism,  produce  little  heat ; 


Time. 

B'aren- 
sprung. 

J.  Davy. 

Hallmann. 

Gierse. 

JUrgensen. 

Jager. 

Morning,  5 

36-7 

36-6 

36-9 

6 

36-'68 

36-7 

36-4 

37-1 

7 

36-94* 

36-63 

36-98 

36-7* 

36-5* 

37-5* 

8 

37-16* 

36-80* 

37-08* 

36-8 

.36-7 

37-4 

9 

36-89 

36-9 

36-8 

37-5 

10 

37-26 

104  =  37-36 

37-23 

37  0 

37-0 

37-5 

11 

36-89 

37-2 

37-2 

37-3 

Mid-day,  12 

36-87 

37-3* 

37-3* 

37-5* 

1 

36-83 

37-21 

37-13 

37-3 

37-3 

37-4 

2 

37-65 

37-50* 

37-4 

37-4 

37-5 

3 

37-15* 

37-43 

37-4* 

37-3* 

37-5 

4 

37-17 

37-4 

37-3 

37-5* 

5 

37-48 

37-05* 

5:^  =  37-31 

37-43 

37-5 

37-5 

37-5 

6 

•  •• 

64=36-83 

37-29 

37-5 

37-6 

37-4 

7 

37-43 

7^  =  36-50* 

37-31* 

37-5* 

37-6* 

37-3 

8 

37-4 

37-7 

37-1* 

9 

37-02* 

37-4 

37-5 

36-9 

10 

37-29 

37-3 

37-4 

36-8 

11 

36-85 

36-72 

36-70 

36-81 

37-2 

37-1 

36-8 

Night,     12 

37-1 

36-9 

36-9 

1 

36'65 

36-44 

37-0 

36-9 

36-9 

2 

... 

... 

36-9 

36-7 

36-8 

3 

36-8 

36-7 

36-7 

4 

36-31 

... 

36-7 

36-7 

36-7 

[*  Indicates  taking  of  food.] 


VARIATIONS   OF  THE   MEAN   TEMPERATURE. 


439 


they  become  cold  sooner,  and  hence  ought  to  wear  warm  clothing  to 
keep  up  their  temperature. 

(4.)  Periodical  Daily  Variations. — In  the  course  of  24  hours  there 
are  regular  periodic  variations  in  the  mean  temperature,  and  these 
occur  at  all  ages.  As  a  general  rule,  the  temperature  continues  to  rise 
during  the  day  (maximum  at  5-8  p.m.),  while  it  continues  to  fall  during 
the  night  (minimum  2-6  a.m.).  The  mean  temperature  occurs  at  the 
third  hour  after  breakfast  (Lichtenfels  and  Frohlich). 

According  to  Lichtenfels  and  Friihlich,  the  morning  temperature  rises  4-6 
hours  after  breakfast  until  its  first  maximum,  then  it  falls  until  dinner  time  ;  and 
it  rises  again  within  two  hours,  to  a  second  maximum,  falls  again  towards  evening, 
while  Slipper  does  not  appear  to  cause  any  ob\aous  mcrease.  The  daily  variation 
of  the  temperature  is  given  in  Fig.  170,  according  to  Liebermeister  and  Jiirgensen. 
Accorduag  to  Bonnal,  the  minimum  occurs  between  12- .S  a.m.  (in  wmter  .36*05, 
in  summer  .S6*45°r.\  the  maximum  between  2-4  p.m. 


Mornin 


Evening. 

Fig.  170. 

Variations  of  the  daily  temperature  in  health  during  24:,hours — L. 
Liebermeister :  .J ,  after  Jiirgensen. 


after 


As  the  variations  occur  when  a  person  is  starved — although  those  tliat  occur  at 
the  periods  at  which  food  ought  to  have  been  taken  are  less— it  is  obvious  that 
the  variations  are  not  due  entirely  to  the  taking  of  food. 

The  daily  variation  in  the  frequency  of  the  pulse  (p.  142)  often  coincides  with 
variation  of  the  temperature.  Biirensprung  found  that  the  mid-day  temperature- 
maximum  slightly  preceded  the  pulse-maximum. 


If  we  sleep  during  the  day,  and  do  all  our  daily  duties  during 
the  night,  the  above  described  typical  course  of  the  temperature  is 
inverted  (Krieger).  With  regard  to  the  effect  of  activity  or  rest,  it 
appears  that  the  activity  of  the  muscles  during  the  day,  tends  to 
increase  the  mean  temperature  slightly,  while  at  night,  the  mean 
temperature  is  less  than  in  the  case  of  a  person  at  rest  (Liebermeister). 


440  CONDITIONS  AFFECTING  THE   MEAN   TEMPERATURE. 

The  peripheral  parts  of  the  body  exhibit  more  or  less  regular  variations  of 
their  temperature.  In  the  palm  of  the  hand,  the  progress  of  events  is  the 
following : — After  a  relatively  high  night-temperature,  there  is  a  rapid  fall  at 
6  a.m.,  which  reaches  its  mmknum  at  9-10  a.m.  This  is  followed  by  a  slow  rise, 
which  reaches  a  high  maximum  after  dianer  ;  it  falls  between  1-3  p.m..  and  after 
two  to  three  hours  reaches  a  minimum.  It  rises  from  6-8  p.m.,  and  falls  again 
towards  morning.  A  rapid  fall  of  the  temperature  in  a  peripheral  part  cor- 
responds to  a  rise  of  temperature  in  internal  parts  (Homer). 

(5.)  Many  operations  upon  the  body  affect  the  temperature.  After 
hcemorrhage,  the  temperature  falls  at  first,  but  it  rises  again  several 
tenths  of  a  degree,  and  is  usually  accompanied  by  a  shiver  or  slight 
rigor;  several  days  thereafter,  it  falls  to  normal,  and  may  even  fall 
somewhat  below  it.  The  sudden  loss  of  a  large  amount  of  blood 
causes  a  fall  of  the  temperature  of  ^-2°C.  Very  long  continued  hse- 
morrhage  (dog)  causes  it  to  fall  to  31°  or  29°C.  (Marshall  Hall). 

This  is  obviously  due  to  the  diminution  of  the  processes  of  oxidation  in  the 
ansemic  body,  and  to  the  enfeebled  circulation.  Similar  conditions  causing 
diminished  metabolism  effect  the  same  result.  Continued  stimulation  of  the 
peripheral  end  of  the  vagus,  so  that  the  heart's  action  is  enormously  slowed, 
diminishes  the  temperature  several  degrees  in  rabbits  (Landois  and  Ammon). 

The  transfusion  of  a  considerable  quantity  of  blood  raises  the  tem- 
perature about  half  an  hour  after  the  operation.  This  gradually 
passes  into  a  febrile  attack,  which  disappears  within  several  hours. 
When  blood  is  transfused  from  an  artery  to  a  vein  of  the  same  animal 
a  similar  result  occurs  (Albert  and  Strieker)  (§  102). 

(6.)  Many  poisons  diminish  the  temperature — e.g.,  chloroform  (Schei- 
nesson),  and  the  anaesthetics,  as  also  alcohol,  digitalis,  quinin,  aconitin, 
muscarin.  These  may  act  upon  the  blood  so  as  to  limit  its  oxidising 
power,  or  they  may  render  the  tissues  less  liable  to  undergo  molecular 
transformations  for  the  production  of  heat.  In  the  case  of  the 
anaesthetics,  the  latter  effect  perhaps  occurs,  and  is  due  possibly  to  a 
semi-coagulation  of  the  nervous  substance  (?). 

The  temperature  is  increased  by  strychnin,  nicotin,  picrotoxin,  veratrin  (Hogyes), 
laudanin  (F.  A.  Falck).  Curara  (muscarin — Hogyes),  laudanosin  (F.  A.  Falck), 
give  an  uncertain  eifect. 

(7.)  Various  diseases  have  a  decided  effect  upon  the  temperature. 
Loewenhardt  found  that  in  insane  persons,  several  weeks  before 
their  death,  the  rectal  temperature  was  30°-31°O. ;  Bechterew  found 
in  dementica  paralytica,  before  death  27'5°C.  (rectum);  the  lowest 
temperature  observed,  and  life  retained,  in  a  drunk  person  was  24°C. 
(Reinke,  Nicolaysen).  The  temperature  is  increased  in  fever,  and 
the  highest  point  reached  just  before  death,  and  recorded  by  Wunder- 
lich,  was  44-65°C.  (compare  §  220). 


REGULATION  OP  THE  TEMPERATURE.  441 

The  mean  height  of  all  the  temperatures  taken  during  a  day  in  a 
patient  is  called  the  ^' daily  mean"  and  according  to  Jaeger  it  is  37 '13°  in 
the  rectum  in  health.  A  daily  mean  of  more  than  37*8°  is  a  "  fever 
temperature,"  while  a  mean  under  37 '©"C.  is  regarded  as  a  "collapse 
temperature." 

214.  Regulation  of  the  Temperature. 

As  the  bodily  temperature  of  man  and  similar  animals  is  nearly  con- 
stant, notwithstanding  great  variations  in  the  temperature  of  their 
siuToundings,  it  is  clear  that  some  mechanism  must  exist  in  the  body, 
whereby  the  heat-economy  is  constantly  regulated.  This  may  be 
brought  about  in  two  ways ;  either  by  controlling  the  transformation 
of  potential  energy  into  heat,  or  by  affecting  the  amount  of  heat  given 
off  according  to  the  amount  produced,  or  to  the  action  of  external 
agencies. 

I.  Regulatory  arrangements  governing  the  production  of  heat. — 
Liebermeister  estimates  the  amount  of  heat  produced  by  a  healthy  man 
at  1"8  calories  per  minute.  It  is  highly  probable  that,  within  the  body, 
there  exist  mechanisms  which  determine  the  molecular  transformations, 
upon  which  the  evolution  of  heat  depends  (Hoppe-Seyler,  Liebermeister). 
This  is  accompHshed  chiefly  in  a  reflex  manner.  The  peripheral  ends  of 
cutaneous  nerves  (by  thermal  stimulation),  or  the  nerves  of  the  intestine 
and  the  digestive  glands  (by  mechanical  or  chemical  stimulation  during 
digestion  or  inanition)  may  be  stimulated,  whereby  impressions  are 
conveyed  to  the  heat-centre  which  sends  out  impvdses  through  efferent 
fibres  to  the  depots  of  potential  energy,  either  to  increase  or  diminish 
the  extent  of  the  transformations  occurring  in  them.  The  nerve 
channels  herein  concerned  are  entirely  unknown.  Many  considerations, 
however,  go  to  support  such  an  hypothesis.  The  following  phenomena 
indicate  the  existence  of  mechanisms  regulating  the  production  of 
heat : — 

(1.)  The  temporary  application  of  moderate  cold  raises  the  bodily 
temperature,  while  heat,  similarly  applied  to  the  external  sm'face, 
lowers  it  (§§222  and  224). 

(2.)  Cooling  of  the  surroundings  increases  the  amount  of  CO.,  excreted, 
by  increasing  the  production  of  heat  (Liebermeister,  Gildermeister), 
while  the  O  consumed  is  also  increased  simultaneously;  heating  the 
surrounding  medium  diminishes  the  CO2  (compare  Resjjiration,  p.  257). 

D.  Fmkler  found,  from  experiments  upon  guinea-pigs,   that  the  production  of 
heat  was  more  than  doubled  when  the  surrounding  temperature  was  diminished 
24°C.     The  metabolism  of  the  guinea-pig  is  increased  in  winter  23  per  cent,  as  com- 
pared with  summer,  so  that  the  same  relation  obtains  as  in  the  case  of  a  diminution 
.  of  the  surrounding  temperature  of  short  duration. 


442  REGULATION  OF  THE  TEMPERATURE. 

C.  Ludwig  and  Sanders-Ezn  found,  that  in  a  rabbit  there  was  a  rapid  increase  in 
the  amount  of  COg  given  off,  when  the  surroundings  were  cooled  from  38°  to  6°-7°C. , 
while  the  excretion  was  diminished  when  the  surrounding  temperature  was  raised 
from  4°-9°  to  35°-37°,  so  that  the  thermal  stimulation,  due  to  the  temperature  of 
the  surrounding  medium,  acted  upon  the  combustion  within  the  body.  Pfliiger 
found  that  a  rabbit  which  was  dipped  in  cold  water  used  more  O  and  excreted 
more  CO2. 

If  the  cooling  action  was  so  great  as  to  reduce  the  bodily  temperature  to  30°,  the 
exchange  of  gases  diminished,  and  where  the  temperature  fell  to  20°,  the  exchange 
of  gases  was  diminished  one-half.  It  is  to  be  remembered,  however,  that  the 
excretion  of  CO2  does  not  go  hand  in  hand  with  the  formation  of  CO2,  so  that  the 
increased  excretion  of  CO2  in  a  cold  bath  is  perhaps  due  to  more  complete  expira- 
tion, andBerthelot  has  proved  that  the  formation  of  CO2  is  not  a  certain  test  of 
the  amount  of  heat  produced.  If  mammals  be  placed  in  a  warm  bath,  which  is 
2°-3°  higher  than  their  own  temperature,  the  excretion  of  CO2  and  the  consump- 
tion of  O  are  increased,  owing  to  the  stimulation  of  their  metabolism  (Pfliiger), 
while  the  excretion  of  urea  is  also  increased  in  animals  (Naiinyn)  and  in  man 
(Schleich). 

(3.)  Cold  acting  upon  the  skin  causes  involuntary  muscular  move- 
ments (shivering,  rigors),  and  also  voluntary  movements,  both  of  which 
produce  heat. 

The  cold  excites  the  action  of  the  muscles,  which  is  connected  with  processes  of 
oxidation  (Pfiiiger).  After  poisoning  with  curara,  which  paralyses  voluntary 
motion,  this  regulation  of  the  heat  falls  to  a  minimum  (Rohrig  and  Zuntz). 

(4.)  Variations  in  the  temperature  of  the  surroundings  affect  the 
appetite  for  food;  in  winter,  and  in  cold  regions,  the  sensation  of 
hunger  and  the  appetite  for  the  fats,  or  such  substances  as  yield  much 
heat  when  they  are  oxidised,  are  increased ;  in  summer,  and  in  hot 
climates,  they  are  diminished.  Thus  the  mean  temperature  of  the 
surroundings,  to  a  certain  extent,  determines  the  amount  of  the  heat- 
producing  substances  to  be  taken  in  the  food.  In  winter  the  amount 
of  ozone  in  the  air  is  greater,  and  thus  the  oxidising  power  of  the 
inspired  air  is  increased. 

II.  Regulatory  mechanisms  governing  the  excretion  of  heat. — 
The  mean  amount  of  heat  given  off  by  the  human  skin  in  24  hours, 
by  a  man  weighing  82  kilos,  is  2,092-2,592  calories — i.e.,  r3G-l-60 
per  minute. 

(1.)  Increased  temperature  causes  dilatation  of  the  cutaneous  vessels; 
the  skin  becomes  red  and  congested,  soft,  and  with  more  fluids,  so  that 
it  becomes  a  better  conductor  of  heat;  the  epithelium  is  moistened,  and 
sweat  appears  upon  the  surface.  Thus  increased  excretion  of  heat 
is  provided  for,  while  the  evaporation  of  the  sweat  also  abstracts  heat. 

Cold  causes  contraction  of  the  cutaneotts  vessels ;  the  skin  becomes 
pale,  less  soft,  poorer  in  juices,  and  collapsed ;  the  epithelium  becomes 
dry,  and  does  not  permit  fluids  to  pass  through  it  to  be  evaporated,  so 
that  the  excretion  of  heat  is  diminished.     The  excretion  of  lieat  from 


REGULATION    OF  THE  TEMPERATtTRE.  443 

the  periphery,  and  the  transverse  thermal  conduction  through  the  skin, 
are  diminished  by  the  contraction  of  the  vessels  and  muscles  of  the 
skin,  and  by  the  expulsion  of  the  well  conducting  blood  from  the 
cutaneous  and  sub-cutaneous  vessels.  The  cooling  of  the  body  is  very- 
much  affected,  owing  to  the  diminution  of  the  cutaneous  blood-stream, 
just  as  occurs  when  the  current  through  a  coil  or  worm  of  a  distillation 
apparatus  is  greatly  diminished  (Winternitz).  If  the  blood-vessels 
dilate,  the  temperature  of  the  surface  of  the  body  rises,  the  difference 
of  temperature  between  it  and  the  surrounding  cooler  medium  is 
increased,  and  thus  the  excretion  of  heat  is  increased.  Tomsa  has 
shown  that  the  fibres  of  the  skin  are  so  arranged  anatomically,  that 
the  tension  of  the  fibres  produced  by  the  erector  pili  muscles  causes  a 
diminution  in  the  thickness  of  the  skin,  this  result  being  brought  about 
at  the  expense  of  the  easily  expelled  blood. 

Landois  and  Hauschild  ligatured  the  arteries  alone,  or  the  arteries 
and  veins  (dog) — e.g.,  the  axillary  artery  and  vein,  the  crurals,  the 
carotids  and  the  jugular  veins,  and  found  that  in  a  short  time  the 
temperature  rose  several  tenths  of  a  degree. 

By  the  systematic  application  of  stimuli — e.g.,  cold  baths,  and  washing  with 
cold  water,  the  muscles  of  the  skin  and  its  blood-vessels  may  be  caused  to  con- 
tract, and  become  so  \agorous  and  excitable,  that  when  cold  is  suddenly  applied 
to  the  body  or  to  a  part  of  it  the  excretion  of  heat  is  energetically  prevented,  so 
that  cold  baths  and  washing  with  cold  water  are,  to  a  certain  extent,  ' '  gym- 
nastics of  the  cutaneous  muscles,"  which,  under  the  above  circumstances,  protect 
the  body  from  cold  (Rosenthal,  du  Bois-Reymond). 

(2.)  Increased  temperature  causes  increased  heart-beats,  while 
diminished  temperature  diminishes  the  number  of  contractions  of  the 
heart  (p.  105).  The  relatively  warm  blood  is  pumped  by  the  action  of 
the  heart  from  the  internal  organs  of  the  body  to  the  surface  of  the  skin, 
where  it  readily  gives  off"  heat.  The  more  frequently  the  same  volume 
of  blood  passes  through  the  skin — 27  heart-beats  being  necessary  for 
the  complete  circuit  of  the  l)lood — the  greater  will  be  the  amount  of 
heat  given  oif  and  conversely.  Hence,  the  frequency  of  the  heart-beat 
is  in  direct  relation  to  the  rapidity  of  cooling  (Walther).  In  very  hot 
air  (over  100°C.)  the  pulse  rose  to  over  160  per  minute.  The  same  is 
true  in  fever  (p.  142).  Liebermeister  gives  the  following  numbers 
with  reference  to  the  temperature  in  an  adult: — 

Pulse-beats,  per  min.,    78-6  — 91-2— 99-8  — 108'5  — 110  — 137-5. 
Temperature  in  C°.,        37°  —  38°  —  39°  —  40°   —  41°  —  42°. 

(3.)  Increased  temperature  increases  the  number  of  respirations.^ 
Under  ordinary  circumstances,  a  much  larger  volume  of  air  passes 
through  the  lungs  when  it  is  warmed  almost  to  the  temperature  of  the 


444  CLOTHING. 

body.  Farther,  a  certain  amount  of  watery  vapour  is  given  off  with 
each  expiration,  which  must  be  evaporated,  whereby  heat  is  abstracted. 
Energetic  respiration  aids  the  circulation,  so  that  respiration  acts 
indirectly  in  the  same  way  as  (2).  According  to  other  observers,  the 
increased  consumption  of  0  favours  the  combustion  in  the  body 
(p.  259,  8),  whereby  the  increased  respiration  must  act  in  producing  an 
amount  of  heat  greater  than  normal.  This  excess  is  more  than  com- 
pensated by  the  cooling  factors  above-mentioned.  Forced  respiration 
produces  cooling,  even  when  the  air  breathed  is  heated  to  54°C.,  and 
saturated  with  watery  vapour  (Lombard). 

(4.)  Covering  of  the  body. — Animals  become  clothed  in  winter  with 
a  winter  fur  or  covering,  while  in  summer  their  covering  is  lighter,  so 
that  the  excretion  of  heat  in  surroundings  of  different  temperatures  is 
thereby  rendered  more  constant.  Many  animals  which  live  in  very 
cold  air  or  water  are  protected  from  too  rapid  excretion  of  heat  by  a 
thick  layer  of  fat  under  the  skin.  Man  provides  for  a  similar  result  by 
adopting  summer  and  winter  clothing. 

The  position  of  the  body  is  also  important ;  pulling  the  parts  of  the 
body  together,  approximation  of  the  head  and  limbs,  keep  in  the  heat ; 
spreading  out  the  limbs,  erection  of  the  hairs,  pluming  the  feathers, 
allow  more  heat  to  be  evolved.  If  a  rabbit  be  kept  exposed  to  the  air 
with  its  legs  extended  for  three  hours,  the  rectal  temperature  will  fall 
from  39°C.  to  37°C.  Man  may  influence  his  temperature  by  remaining 
in  a  warm  or  a  cold  room — by  taking  hot  or  cold  drinks,  hot  or  cold 
baths — remaining  in  air  at  rest  or  air  in  motion,  e.g.,  by  using  a  fan. 

Stimulation  of  the  central  end  of  a  sensory  nerve  (sciatic)  increases  the  surface 
temperature  and  diminishes  the  internal  temperature  (Ostroumow,  Mitropolsky). 

Clothing. 

Warm  clothing  is  the  equivalent  of  food. — As  clothes  are  intended  to  keep  in  the 
heat  of  the  body,  and  heat  is  produced  by  the  combustion  and  oxidation  of  the 
food,  we  may  say,  the  body  takes  ia  heat  directly  in  the  food,  while  clothing  pre- 
vents it  from  giving  off  too  much  heat.  Summer  clothes  weigh  3-4  kilo.,  and 
winter  ones,  6-7  kilo. 

In  connection  with  clothes,  the  following  considerations  are  of  importance : — 
(1.)  Their  cax^acity  for  conduction. — Those  substances  which  conduct  heat  badly 
keep  us  warmest.  Hare-skin,  down,  beaver-skin,  raw  silk,  taffeta,  sheeps'  wool, 
cotton  wool,  flax,  spun-silk,  are  given  in  order,  from  the  worst  to  the  best  con- 
ductors. (2.)  The  capacity  for  radiation. — Coarse  materials  radiate  more  heat 
than  smooth,  but  colour  has  no  effect.  (3.)  Relation  to  the  sun^s  rays. — Dark 
materials  absorb  more  heat  than  light-coloured  ones,  (4.)  Their  hygroscopic 
properties  are  important,  whether  they  can  absorb  much  moisture  from  the  skin 
and  gradually  give  it  off  by  evaporation  or  the  reverse.  The  same  weight  of  wool 
takes  up  twice  as  much  water  as  linen;  hence,  the  latter  gives  it  off  in  evaporation 
more  rapidly.  Flannel  next  the  skin,  therefore,  is  not  so  easily  moistened,  nor 
•does  it  so  rapidly  become  cold  by  evaporation;  hence,  it  protects  against  the 


INCOME   AND   EXPENDITURE   OF   HEAT.  445 

action  of  cold.  (5.)  The  permeability  for  air  ia  of  importance,  but  does  not  stand 
in  relation  with  the  heat-conducting  capacity.  The  following  substances  are 
arranged  in  order  from  the  most  to  the  least  permeable— flannel,  buckskin,  linen, 
silk,  leather,  waxcloth. 


215.  Income  and  Expenditure  of  Heat- 
Balance  of  Heat. 

As  the  temperature  of  the  body  is  maintained  within  narrow  limits, 
the  amount  of  heat  taken  in  must  balance  the  heat  given  off,  i.e.,  exactly 
the  same  amount  of  potential  energy  must  be  transformed  in  a  given 
time  into  heat,  as  heat  is  given  off  from  the  body. 

An  adult  produces  as  much  heat  in  half  an  hour  as  will  raise  the 
temperature  of  his  body  1°C.  If  no  heat  was  given  off,  the  body 
would  become  very  hot  in  a  short  time ;  it  would  reach  the  boiling- 
point  in  36  hours,  supposing  the  production  of  heat  continued 
uninterruptedly. 

The  following  are  the  most  important  calculations  on  this  subject : — 

A.  According  to  Helmholtz. 

Helmholtz  was  the  first  to  estimate  numerically  the  amount  of  heat  produced  by 
a  man. 

(1.)  Heat-income. — («)  A  healthy  adult,  weighing  82  kilos., 
expires  in  24  hours,  878 "4  grms.  CO2  (Scharling).  The 
combustion  of  the  C  therein  into  CO2  produces       .         .     1,730,760  Cal. 

(b)  But  he  takes  in  more  O  than  reappears  in  the  CO2 ;  the 

excess  is  used  in  oxidation- processes,  e.g.,  for  the  forma- 
tion of  H2O,  by  union  with  H,  so  that  13,615  grms.  H 
will  be  oxidised  by  the  excess  of  O,  which  gives      .        .        318,600     ,, 

2,049,360  Cal. 

(c)  About  25  per  cent,  of  the  heat  must  be  referred  to  sources 

other  than  combustion  (Dulong),  so  that  the  total        =     2,732,000  Cal. 

2,732,000  calories  are  actually  sufficient  to  raise  the 
temperature  of  an  adult  weighing  80-90  kilos.,  from  10"  to 
38-39°C.,  i.e.,  to  a  normal  temperature. 

(2.)  Heat-expenditure. — («)    Heating  the  food 

and  drink,  which  have  a  mean  temperature 

of  12°C 70,157  Cal.  =    2-6  per  cent. 

(6)  Heating  the  air  respired  :=  16,400  grm.,  with  an 

initial  temperature  of  20°C.  .        .  70,032   ,,     =   2-6      ,, 

( When  the  temperature  of  the  air  is  0<*,  140,064  Cal.  =i5'2  per  cent. ) 

(c)  Evaporation  of  656  grm.  water  by  the  lungs,       397,536  Cal.  =  14-7  per  cent. 

(d)  The    remainder    given    off    by  radiation    and 

evaporation  of  water  by  the  skin,         (77  '5  per  cent,  to")  =  80*1  per  cent. 


446  INCOME   AND   EXPENDITURE   OF   HEAT. 

B.  According  to  Dulong. 

(1.)  Heat-income. — Dulong,  and  after  him  Boussingault,  Liebig  and  Dumas, 
sought  to  estimate  the  amount  of  heat  from  the  C  and  H  contained  in  the  food. 
As  we  know  that  the  combustion  of  1  grm.  C  =  8,040  heat-units,  and  1  grm.  H  = 
34,460  heat-units,  it  would  be  easy  to  determine  the  amount  of  heat  were  the  C 
simply  converted  into  COg  and  the  H  into  H2O.  But  Dulong  omitted  the  H  in 
the  carbohydrates  {e.g.,  grape-sugar  =  CeHiaOe)  as  producing  heat,  because 
the  H  is  already  combined  with  0,  or  at  least  is  the  proportion  in  which  it  exists 
in  water. 

This  assumption  is  hypothetical,  for  the  atoms  of  C  in  a  carbohydrate  may  be 
so  firmly  united  to  the  other  atoms,  that  before  oxidation  can  take  place,  their 
relations  must  be  altered,  so  that  potential  energy  is  used  up,  i.e.,  heat  must  be 
rendered  latent;  so  that  these  considerations  rendered  the  following  example  of 
Dulong's  method  given  by  Vierordt  very  problematical. 

An  adult  eats  in  24  hours,  120  grm.  proteids,  90  grm.  fat,  and  340  grm.  starch 
(carbohydrates).     These  contain: — 

Gram.  C.  H. 

Proteids,         ....         120  contain    64,18  and    8,60 
Fat,         .....  90        „         70,20    „     10,26 

Starch,  ....        330       „       146,82    „       ... 


281,20  and  18,86 
The  urine  and  f feces  contain  still  unconsumed,    29,8      ,,      6,3 


Remainder  to  be  burned,      ....       251,4    and  12,56 
As  1  grm.  C  =  8,040  heat-units  and  1  grm.  H  =  34,460  heat-units,  we  have  the 
following  calculation : — 

251,4    X    8,040  =  2,031,312  (from  combustion  of  C). 
12,56  X  34,460=    432,818  (    „  „  H). 


2,464,130  heat-units. 

(2.)  Heat-expenditure:— 


Heat-units.    Per  cent,  of 
the  excreta. 


1.  1,900  grm.  are  excreted  daily  by  the  urine  and 

faeces,  and  they  are  25°  warmer  than  the  food,  47,500          1  "8 

2.  13,000  grm.  air  are  heated  (from  12°  to  37°C.) 

(heat-capacityof  the  air  =0-26),      .         .         .  84,500          3-5 

3.  330  grm.  water  are  evaporated  by  the  respiration 

(1  grm.  =  582  heat-units),         .         .         .         .  192,060          7*2 

4.  660  grm.  water  are  evaporated  from  the  skin,  384,120        14*5 

Total, 708,180 

Remainder  radiated  and  conducted  from  the  skin,     1,791,810  72 


Total  amount  of  heat-units  given  off,         .  2,500,000         100 

C.   Heat-income,  according  to  Frankland. 

Frankland  burned  the  food  directly  in  a  calorimeter,  and  found  that  1  grm.  of 
the  following  substances  yielded: — 

Albumin, 4,998  heat-units. 

Grape-sugar,       ....      3,277       „ 
Ox  fat, 9,069 


VARIATIONS   IN  HEAT-PRODUCTION.  447 

The  albumin,  however,  is  only  oxidised  to  the  stage  of  urea,  hence  the  heat- 
units  of  urea  must  be  deducted  from  4,998,  which  gives  4,263  heat-units  obtainable 
from  1  grm.  albumin.  When  we  know  the  number  of  grammes  consumed,  a 
simple  multiplication  gives  the  number  of  heat-units. 

The  heat-units  will  vary,  of  course,  with  the  nature  of  the  food.  J.  Ranke 
gives  the  following: — 

With  animal  diet, 2,779,524  heat-units. 

„    food  free  from  N,    ....       2,059,506 

,,     mixed  diet, 2,200,000 

„    during  hunger,      ....       2,012,816 

216.  Variations  in  Heat-production. 

According  to  Helmholtz,  an  adiilt  weighing  82  kilos,  produces  2,732,000  calories 
in  24  hours. 

(I.)  Influence  of  the  body-iveight.  —  Accepting  the  above  number,  Immermann  has 
given  the  following  formula  for  the  heat-production  in  living  tissues: — 

w:W=^p:   ^r- 
(where  W  =  2, 732,000;  P  =  82  kilos.  [W  :  ^p  =  144,75];  p=body-weight   of  the 
person  to  be  investigated,  and  w  represents  the  heat-production  which  is  required. ) 

It  is  highly  desirable  that  W  :  ^^n"  ( =  m)  was  ascertained  as  a  mean  from  a 
large  number  of  observations,  then  the  heat  production  for  any  body-weight  p 
would  be 

w  =  m  ^/pZ. 

(2.)  Age  and  Sex. — The  heat-production  is  less  in  infancy  and  in  old  age,  and  it 
is  less  in  proportion  in  the  female  than  in  the  male. 

(3.)  Daily  Variation. — The  heat-production  shows  variations  in  24  hours  corre- 
sponding with  the  temperature  of  the  body  (§  213,  4). 

(4.)  The  heat-production  is  greater  in  the  waking  condition,  during  physical  and 
mental  exertion,  and  during  digestion,  than  in  the  opposite  conditions. 


217.  Relation  of  Heat-production  to  the 
Work  of  the  Body. 

The  potential  energy  supplied  to  the  body  may  be  transformed  into 
heat  and  potential  energy  (see  Introduction).  In  the  passive  condition, 
almost  all  the  potential  energy  is  changed  into  heat ;  the  workman,  how- 
ever, transforms  potential  energy  into  work — mechanical  work — in 
addition  to  heat.  These  two  may  be  compared  by  using  an  equivalent 
measurement,  thus,  1  heat-unit  (energy  required  to  raise  1  gramme  of 
water  1°C.)==425'5  gramme-metres. 

The  following  example  may  serve  to  illustrate  the  relation  between  heat- 
production  and  the  production  of  work: — Suppose  a  small  steam-engine  to  be  placed 
within  a  capacious  calorimeter,  and  a  certain  quantity  of  coal  to  be  burned,  then 
as  long  as  the  engine  does  not  perform  any  mechanical  work,  heat  alone  is  produced 
by  the  burning  of  the  coal.  Let  this  amount  of  heat  be  estimated,  and  a  second 
experiment  made  by  burning  the  same  amount  of  coal,  but  allow  the  engine  to  do 


448  RELATION    OF    HEAT-PRODUCTION    TO    WORK. 

a  certain  amount  of  work — say,  raise  a  weight — by  a  suitable  arrangement.  This 
work  must,  of  course,  be  accomplished  by  the  potential  energy  of  the  heating 
material.  At  the  end  of  this  experiment,  the  temperature  of  the  water  will  be 
much  less  than  in  the  first  experiment,  i.  e.,  fewer  heat-units  have  been  transferred 
to  the  calorimeter  when  the  engine  was  heated  than  when  it  did  no  work. 

Comparative  experiments  of  this  nature  have  shown,  that  in  the  second  experi- 
ment the  useful  work  is  very  nearly  proportional  to  the  decrease  of  the  heat 
(Hirn). 

In  good  steam-engines  only  •^,  and  in  the  very  best  ^,  of  the  potential  energy 
is  changed  into  mechanical  energy,  while  ^-^  passes  into  heat. 

Compare  this  with  what  happens  within  the  body: — ^A  man  in  a 
passive  condition  forms  from  the  potential  energy  of  the  food  between 
2j-2f  million  calories.  The  ivorh  done  by  a  workman  is  reckoned  at 
200,000  kilogramme-metres. 

If  the  organism  were  entirely  similar  to  a  machine,  a  smaller  amount 
of  heat,  corresponding  to  the  work  done,  would  be  formed  in  the  body. 
As  a  matter  of  fact,  the  organism  produces  less  heat  from  the  same 
amount  of  potential  energy  when  mechanical  work  is  done.  There 
is  one  point  of  difference  between  a  workman  and  a  working  machine. 
The  workman  consumes  much  more  potential  energy  in  the  same  time 
than  a  passive  person ;  much  more  is  burned  in  his  body,  and  hence, 
the  increased  consumption  is  not  only  covered,  but  even  over-com- 
pensated. Hence,  the  workman  is  warmer  than  the  passive  person,  owing 
to  the  increased  muscular  activity  (§  210,  1,  h).  Take  the  following 
example  : — Hirn  (1858)  remained  passive,  and  absorbed  30  grm.  0  per 
hour  in  a  calorimeter,  and  produced  155  calories.  When  in  the  calori- 
meter he  did  work  equal  to  27,450  kilogramme-metres,  which  was 
transferred  beyond  it;  he  absorbed  132  grm.  0,  and  produced  only 
251  calories. 

In  estimating  the  work  done,  we  must  include  only  the  heat  equivalent  of  the 
work  transferred  beyond  the  body;  lifting  weights,  pushing  anything,  throwing 
a  weight,  and  lifting  the  body,  are  examples.  In  ordinary  walking,  there  is  no  loss 
of  heat  (apart  from  overcoming  the  resistance  of  the  air);  when  descending  from  a 
height  there  may  be  increased  warmth  of  the  body. 

The  organism  is  superior  to  a  machine  in  as  far  as  it  can,  from  the 
same  amount  of  potential  energy,  produce  more  work  in  proportion  to 
heat.  Whilst  the  very  best  steam-engine  gives  ^  of  the  potential 
energy  in  the  form  of  work,  and  f  as  heat,  the  body  produces  -J  as 
work  and  -|  as  heat,  Cliemical  energy  can  never  do  work  alone,  in  a 
living  or  dead  motor,  without  heat  being  formed  at  the  same  time. 

218.  Accommodation  for  Varying  Degrees  of 
Temperature. 

All  substances  which  possess  high  conductivity  for  heat,  when 
brought  into  contact,  with  the  skin,  appear  to  be  very  much  colder  o? 


ACCOSIMODATION  FOR  VARYING  TEMPERATURES.  449 

hotter  than  bad  conductors  of  heat.  The  reason  of  this  is  that  these 
bodies  abstract  far  more  heat,  or  conduct  more  heat  than  other  bodies. 
Thus  the  water  of  a  cool  bath,  being  a  better  conductor  of  heat,  is 
always  thought  to  be  colder  than  air  at  the  same  temperature.  In  our 
climate  it  appears  to  us  that 


Air, 

at  18°C.,  is  moderately  warm; 
„  25''-28''C.,  hot; 
above  28°,  very  hot. 


Water, 

at  18»C.,  is  cold; 
from  18-29°C.,  cool; 

,,    29-35-5''C.,  warm; 

,,    37  "5  and  above,  hot. 


As  long  as  the  temperature  of  the  body  is  higher  than  that  of  the 
surrounding  medium,  heat  is  given  off,  and  that  the  more  rapidly  the 
better  the  conducting  power  of  the  surrounding  medium.  As  soon  as 
the  temperature  of  the  surrounding  medium  rises  higher  than  the 
temperature  of  the  body,  the  latter  absorbs  heat,  and  it  does  so  the  more 
rapidly  the  better  the  conducting  power  of  the  medium.  Hence,  hot 
water  appears  to  be  warmer  than  air  at  the  same  temperature.  A 
person  may  remain  eight  minutes  in  a  bath  at  45-5°C.  (dangerous  to 
life!);  the  hands  maybe  plunged  into  water  at  50'5°C.,  but  not  at 
5r65°C.,  while  at  60°  violent  pain  is  produced. 

A  person  may  remain  for  eight  minutes  in  air  heated  to  99*95- 
127°C.,  and  a  temperature  of  132°C.  has  been  borne  for  ten  minutes 
(Tillett,  1763).  The  body-temperature  rises  only  to  38-6-38-9° 
(Fordyce,  Blagden,  1774).  This  depends  upon  the  air  being  a  bad 
conductor,  and  thus  it  gives  less  heat  to  the  body  than  water  would  do. 
Farther,  and  what  is  more  important,  the  skin  becomes  covered  with 
sweat,  which  evaporates  and  abstracts  heat,  while  the  lungs  also  give 
off  more  watery  vapour.  The  enormously  increased  heart-beats — over 
160 — and  the  dilated  blood-vessels,  enable  the  skin  to  obtain  an  ample 
supply  of  blood  for  the  formation  and  evaporation  of  sweat.  In  proportion 
as  the  secretion  of  sweat  diminishes,  the  body  becomes  unable  to  endure 
a  hot  atmosphere;  hence  it  is  that  in  air  containing  much  watery  vapour  a 
person  cannot  endure  nearly  so  high  a  temperature  as  in  dry  air,  so 
that  heat  must  accumulate  in  the  body.  In  a  Turkish  vapour  bath 
of  53°  to  60°C.,  the  rectal  temperature  rises  to  40-7-41-G°C.  (Barthels, 
Jiirgensen,  Krishaber).  A  person  may  work  continuously  in  air  at 
31°C.  which  is  almost  satiurated  with  moisture  (StapfF). 

If  a  person  be  placed  in  water  at  the  temperature  of  the  body,  the 

normal  temperature  rises  1°0.  in  1  hour,  and  in  1|  hours  about  2°C. 

(Liebermeister).     A  gradual  increase  of  the  temperature  from  38'6  to 

40-2°C.  causes  the  axillary  temperature  to  rise  to  39-0°C.  within  fifteen 

minutes. 

29 


450  STORAGE  OF  HEAT  IN  THE  BODY. 

Rabbits  placed  in  a  warm  box  at  36*0.  acquire  a  constant  temperature  of  42*'C.,' 
and  lose  weight;  but  if  the  temperature  of  the  box  be  raised  to  4:0°,  death  occurs, 
the  body-temperature  rising  to  45  °C.  (J.  Rosenthal). 

219.  Storage  of  Heat  in  the  Body. 

As  the  uniform  temperature  of  the  body,  under  normal  circumstances, 
is  due  to  the  reciprocal  relation  between  the  amount  of  heat  produced 
and  the  amount  given  off,  it  is  clear  that  heat  must  be  stored  up  in  the 
body  when  the  evolution  of  heat  is  diminished.  The  skin  is  the  chief 
organ  regulating  the  evolution  of  heat;  when  it  and  its  blood-vessels 
contract,  the  heat  evolved  is  diminished,  when  they  dilate  it  is  increased. 
Heat  may  be  stored  up  when — 

(a)  The  skin  is  extensively  stimulated,  whereby  the  cutaneous  vessels  are  tem- 
porarily contracted  (Rbhrig).  (&)  Any  other  circumstances  prevent  heat  from 
being  given  off  by  the  skin  (Winternitz).  (c)  When  the  vaso-motor  centre  is 
excited,  causing  all  the  blood-vessels  of  the  body — those  of  the  skin  included — to 
contract.  This  seems  to  be  the  cause  of  the  rise  of  temperature  after  transfusion 
of  blood  (Landois),  and  the  rise  of  temperature  after  the  sudden  removal  of  water 
from  the  body  seems  to  admit  of  a  similar  explanation ;  as  the  inspissated  blood 
occupies  less  space,  and  the  contracted  vessels  of  the  skin  admit  less  blood. 
(d)  When  the  circulation  in  the  cutaneous  vessels  of  a  large  area  is  mechanically 
slowed,  or  when  the  smaller  vessels  are  plugged  by  the  injection  of  some  sticky 
substance,  or  by  the  transfusion  of  foreign  blood,  the  temperature  rises  (§  102). 
Landois  found  that  ligature  of  both  carotids,  and  the  axillary  and  crural  arteries, 
caused  a  rise  of  1°C.  within  two  hours. 

It  is  also  obvious  that  when  a  normal  amount  of  heat  is  given  off,  an 
increased  production  of  heat  must  raise  the  temperature.  The  rise  of  the 
temperature  after  muscular  or  mental  exertion,  and  during  digestion 
seems  to  be  caused  in  this  way.  The  rise  which  occurs  several  hours 
after  a  cold  bath  is  probably  due  to  the  reflex  excitement  of  the  skin 
causing  an  increased  production  (Jiirgensen). 

When  the  temperature  of  the  body,  as  a  whole,  is  raised  6°C.,  death 
takes  place,  as  in  sunstroke.  It  seems  as  if  there  was  a  molecular  de- 
composition of  the  tissues  at  this  temperature;  while,  if  a  slightly 
lower  temperature  be  kept  up  continuously,  fatty  degeneration  of  many 
tissues  occurs  (Litten).  If  animals,  which  have  been  exposed  artifici- 
ally to  a  temperature  of  over  42°-4:4°C,,  be  transferred  to  a  cooler 
atmosphere,  their  temperature  becomes  sub-normal  (36°C.)  and  may 
remain  so  for  several  days. 

220.  Fever. 

Fever  consists  in  a  greatly  increased  tissue  metabolism  (especially  in  the  muscles-— 
Finkler,  Zuntz),  with  simultaneous  increase  of  the  temperature.  Of  course  the 
mechanism  regulating  the  balance  of  formation  and  expenditure  of  heat  is  disturbed. 


FEVER  AND   ITS  PHENOSIENA.  451 

During  fever,  the  body  is  greatly  incapacitated  for  performing  mechanical  work. 
It  is  evident,  therefore,  that  the  large  amount  of  potential  energy  transformed  is 
almost  all  converted  into  heat,  so  that  the  non-transformation  of  the  energy  into 
mechanical  work  is  another  im2)ortant  factor. 

We  may  take  intermittent  fever  or  ag^e  as  a  type  of  fever,  in  which  violent 
attacks  of  fever  of  several  hours  duration  alternate  with  periods  free  from  fever. 
This  enables  us  to  analyse  the  symj)toms.     The  symptoms  of  fever  are : — 

(1.)  The   increased  temperature  of  the  body.— (3S°-39°C.,  slight;  from 

39°-41°C.  and  upwards,  severe).  The  high  temperature  occurs  not  only  in  cases 
where  the  skin  is  red,  and  has  a  hot  burning  feeluig  (calor  mordax),  but  even 
during  the  rigor  or  the  shivering  stage,  the  temperature  is  raised  (Ant.  de  Haen, 
1760).  The  congested  red  skin  is  a  good  conductor  of  heat,  while  the  pale  blood- 
less skin  conducts  badly;  hence,  the  former  feels  hot  to  the  touch  (v.  Barensprung — 
compare  §  212), 

(2.)  The  increased  production  of  heat  (assumed  by  Lavoisier  and  Crawford) 
is  proved  by  calorimetric  observations.  This  is,  in  small  part,  due  to  the  increased 
acti\aty  of  the  circulation  being  changed  into  heat  (§  206,  2,  a),  but  for  the  most 
part  it  is  due  to  increased  combustion  within  the  body. 

(3.)  The  increased  metabolism  gives  rise  to  the  "consuming"  or  "wasting  " 
character  of  fever,  wliich  was  known  to  Hippocrates  and  Galen,  and  in  1852  v. 
Barensprung  asserted  that  "all  the  so-called  febrile  symptoms  show  that  the 
metabolism  is  increased."  The  increase  of  the  metabolism  is  shown  in  the 
increased  excretion  of  CO2  =  70°-80°  per  cent.  (Leyden  and  Frankel),  while  more 
0  is  consumed,  although  the  respiratory  quotient  remains  the  same  (Zuntz  and 
Lilienfeld).  According  to  D.  Finkler,  the  COo  excreted  shows  greater  variations 
than  the  0  consumed.  The  excretion  of  urea  is  increased  ^  to  f .  In  dogs  suffering 
from  septic  fever,  Naimyn  observed  that  the  urea  began  to  increase  before  the  temper- 
ature rose,  ' '  prefehrile  rise. "  Part  of  the  urea,  however,  is  sometimes  retained 
during  the  fever,  and  appears  after  the  fever  is  over,  "  epicritical  excretion  of 
urea"  (Naunyn).  The  uric  acid  is  also  increased;  the  urine  pigment  (§  19) 
derived  from  the  haemoglobin,  may  be  increased  20  times,  while  the  excretion  of 
-potash  may  be  seven-fold. 

It  is  important  to  observe,  that  the  oxidation  or  combustion  processes  within  the 
body  of  the  fever  patient,  are  greatly  increased,  when  he  is  placed  in  a  warmer 
atmosphere.  The  oxidation  processes  in  fever,  however,  are  also  increased  imder 
the  influence  of  cooZer  surroundings  (§214:,  I,  2),  but  the  increase  of  the  oxidation  in  a 
warm  medium  is  very  much  greater  than  in  the  cold  (D.  Finkler).  The  amount 
of  CO2  in  the  blood  is  diminished,  but  not  at  once  after  the  onset  even  of  a  very 
severe  fever  (Goppert). 

(4.)  The  diminished  excretion  of  heat  varies  in  different  stages  of  a  fever. 
We  distinguish  several  stages  in  a  fever — (a)  The  COld  Stage,  when  the  loss  of 
heat  is  greatly  diminished,  owing  to  the  pale  bloodless  skin,  but  at  the  same  time 
the  heat-production  is  increased  14-2^  times.  The  sudden  and  considerable  rise  of 
the  temperature  during  this  stage  shows  that  the  diminished  excretion  of  heat  is  not 
the  only  cause  of  the  rise  of  the  temperature.  (5)  During  the  hot  stage,  the  heat 
given  offivom.  the  congested  red  skin  is  greatly  increased,  but  at  the  same  time  more 
heat  is  produced.  Liebermeister  assumes  that  a  rise  of  1,  2,  3,  4°C.  corresponds 
to  an  increased  production  of  heat  of  6,  12,  18,  24  per  cent,  (c)  In  the  sweating 
stage,  the  excretion  of  heat  through  the  red  moist  skin  and  evaporation  are 
greatest,  more  than  two  to  three  times  the  normal  (Leyden).  The  heat-production 
is  either  increased,  normal,  or  sub-normal,  so  that  under  these  conditions  the 
temperature  may  also  be  sub-normal  (36°C.), 

(5.)  The  heat-regulating  mechanism  is  injured.— A  warm  temperature 

of  the  surroundings  raises  the  temperature  of  the  fever  patient  more  than  it  does 
that  of  a  non-febrile  person.      The   depression  of  the  heat-production,  which 


452  ARTIFICIAL  INCREASE   OP  THE  BODILY   TEMPERATURE. 

enables  normal  animals  to  maintain  their  normal  temperature  in  a  warm  medium 
(§  214),  is  much  less  in  fever  (D.  Finkler). 

The  accessory  phenomena  of  fever  are  very  important : — Increase  in  the 
intensity  and  number  of  the  heart-beats  (§  214,  II,  2)  and  respirations  (in  adults  40, 
and  children  60  per  min.),  both  being  compensatory  phenomena  of  the  increased 
temperature;  further,  diminished  digestive  activity  (§  186,  D)  and  intestinal 
movements ;  disturbances  of  the  cerebral  activities ;  of  secretion ;  of  muscular 
activity;  slower  excretion — e.g.,  of  potassium  iodide  through  the  urine  (Bachrach, 
Scholze).    In  severe  fever,  molecular  degenerations  of  the  tissues  are  very  common. 

For  the  condition  of  the  blood- corpuscles  in  fever  see  p.  23,  the  vascular  ten- 
sion, §  69;  the  saliva,  §  146. 

Quinine,  the  most  important  febrifuge,  causes  a  decrease  of  the  temperature  by 
limiting  the  production  of  heat  (Lewizky,  Binz,  Naunyn,  Quincke,  Amtz).  Toxic 
doses  of  the  metallic  salts  act  in  the  same  way,  while  there  is  at  the  same  time 
diminished  formation  of  CO2  (Luchsinger). 


221.  Artificial  Increase  of  the  Bodily  Temperature. 

If  mammals  are  kept  constantly  in  air  at  40°C.,  the  excretion  of 
heat  from  the  body  ceases,  so  that  the  heat  produced  is  stored  up.  At 
first,  the  temperature  falls  somewhat  for  a  very  short  time  (Obernier), 
but  soon  a  decided  increase  occurs.  The  respirations  and  pulse  are 
increased,  while  the  latter  becomes  irregular  and  weaker.  The  0 
absorbed  and  COg  given  off  are  diminished  after  6-8  hours  (Litten), 
and  death  occurs  after  great  fatigue,  feebleness,  spasms,  secretion  of 
saliva,  and  loss  of  consciousness,  when  the  bodily  temperature  has  been 
increased  4°  or  at  most  6°C.  Death  does  not  take  place,  owing  to  rigidity 
of  the  muscles,  for  the  coagulation  of  the  myosin  of  mammals'  muscles 
occurs  at  49-50°C.,  in  birds  at  53°C.,  and  in  frogs  at  40°0.  If 
mammals  are  suddenly  placed  in  air  at  100°C.,  death  occurs  (in  15-20 
min.)  very  rapidly,  and  with  the  same  phenomena,  while  the  bodily 
temperature  rises  4-5  °C.  In  rabbits,  the  body-weight  diminishes 
1  grm.  per  min.  Birds  bear  a  high  temperature  somewhat  longer; 
they  die  when  their  blood  reaches  48-50°C. 

Even  man  may  remain  for  some  time  in  air  at  100-110-132*0., 
but  in  1 0-1 5  minutes  there  is  danger  to  life.  The  skin  is  burning  to 
the  touch,  is  red,  a  copious  secretion  of  sweat  bursts  forth,  and  the 
cutaneous  veins  are  fuller  and  redder  (Crawford).  The  pulse  and 
respirations  are  greatly  accelerated.  Violent  headache,  vertigo,  feeble- 
ness, stupefaction  indicate  great  danger  to  life.  The  rectal  temperature 
is  only  1-2°C.  higher.  The  high  temperature  of  fever  may  even  be 
dangerous  to  human  life.  If  the  temperature  remains  for  any  length 
of  time  at  42'5°C.,  death  is  almost  certain  to  occur.  Coagulation  of  the 
blood  in  the  arteries  is  said  to  occur  at  42'6°C.  (Weikart).  If  the 
artificial  heating  does  not  produce  death,  fatty  infiltration  and  degenera- 


USE  OF  HEAT — POST-MORTEM  TEMPERATURE.  453 

tion  of  the  liver,  hearfc,  kidneys,  and  muscles  begin  after  36-48  hours 

(Litten). 

Cold-blooded  animals,  if  placed  in  hot  air  or  warm  water,  soon  have  their 
temperature  raised  6-1 0'C.  The  highest  temperature  compatible  with  life  in  a  frog 
must  be  below  40°C. ,  as  the  frog's  heart  and  muscles  begin  to  coagulate  at  this 
temperature.  Death  is  preceded  by  a  stage  resembling  death,  during  which  life 
may  be  saved. 

Most  of  the  juicy  plants  die  in  half  an  hour  in  air  at  52°C.,  or  in  water  at 
46°C.  (Sachs).  Dried  seeds  of  corn  may  still  germinate  after  long  exposure  to  air 
at  120°C.  Lowly  organised  plants,  such  as  alga%  may  live  in  water  at  60°C. 
(Hoppe-Seyler).  Several  bacteria  withstand  a  boiling  temperature  (Tyndall, 
Chamberland). 


222.  Employment  of  Heat. 

Action  of  Heat. — The  short,  but  not  intense,  action  of  heat  on  the  surface 
causes,  in  the  first  place,  a  transient  slight  decrease  of  the  bodily  temperature, 
partly  because  it  retards  reflexly  the  production  of  heat  (Kernig),  and  partly  be- 
cause, oAving  to  the  dilatation  of  the  cutaneous  vessels  and  the  stretching  of  the  skin, 
more  heat  is  given  off  (Senator).  A  warm  bath  above  the  temperature  of  the 
blood  at  once  increases  the  bodily  temperature. 

Therapeutic  Uses. — The  application  of  heat  to  the  entire  body  is  used  where 
the  bodily  temperature  has  fallen,  or  is  likely  to  fall,  very  low,  as  in  algid  stage  of 
cliolera,  and  in  infants  born  prematurely.  The  general  application  of  heat  is 
obtained  by  the  use  of  warm  baths,  packing,  vapour,  insolation,  and  the  copious 
use  of  hot  drinks.  The  local  application  of  heat  is  obtained  by  the  use  of  warm 
wrappings,  partial  baths,  plunging  the  parts  in  warm  earth  or  sand,  or  placing 
wounded  parts  in  chambers  filled  with  heated  air.  After  removal  of  the  heating 
agent,  care  must  be  taken  to  prevent  the  great  escape  of  heat  due  to  the  dilatation 
of  the  blood-vessels. 


223.  Increase  of  Temperature— Post-mortem 
Phenomena. 

Heidenhain  found  that  in  a  dead  dog,  before  the  body  cooled,  there  was  a  constant 
temporary  rise  of  the  temperature,  which  slightly  exceeded  the  normal.  The  same 
observation  had  been  occasionally  made  on  human  bodies  immediately  after  death, 
especially  when  death  was  preceded  by  muscular  spasms.  Thus,  Wunderlich 
measured  the  temperature  57  minutes  after  death  in  a  case  of  tetanus,  and  found 
ittobe45-375°C. 

The  causes  are  : — 

(1.)  ^  temporary  increased  production  of  heat  after  death,  due  chiefly  to  the 
change  of  the  semi-solid  myosin  of  the  muscles  into  a  solid  form  (rigor  mortis). 
As  the  muscle  coagulates,  heat  is  produced  (v.  Walther,  Fick).  All  conditions 
which  cause  rapid  and  intense  coagulation  of  the  muscles — e.g.,  spasms,  favour  a 
post-mortem  rise  of  temperature  (see  Physiology  of  Muscle) ;  a  rapid  coagulation 
of  the  blood  has  a  similar  result  (p.  42). 

(2.)  Immediately  after  death,  a  series  of  cJiemical processes  occnr -within  the  body, 
whereby  heat  is  produced.  Valentin  placed  dead  rabbits  in  a  chamber,  so  that 
no  heat  could  be  given  off  from  the  body,  and  he  found  that  the  internal  tempera- 
ture of  the  animal's  body  was  increased.     The  processes  which  cause  a  rise  of 


454  ACTION  OF  COLD  ON  THE  BODY. 

temperature  post  mortem  are  more  active  during  the  first  than  the  second  hour; 
and  the  higher  the  temperature  at  the  moment  of  death,  the  greater  is  the  amount 
of  heat  evolved  post  mortem  (Quincke  and  Brieger). 

(3.)  Another  cause  is  the  diminished  excretion  of  heat  postmortem.  After  the 
circulation  is  abolished,  within  a  few  minutes  little  heat  is  given  off  from  the 
surface  of  the  body,  as  rapid  excretion  implies  that  the  cutaneous  vessels  must  be 
continually  filled  with  warm  blood. 


224.  Action  of  Cold  on  the  Body. 

A  short  temporary  slight  cooling  of  the  skin  (removing  one's  clothes 
in  a  cool  room,  a  cool  bath  for  a  short  time,  or  a  cool  douche)  causes 
either  no  change  or  a  slight  rise  in  the  hodily  temperature  (Lieber- 
meister).  The  slight  rise,  when  it  occurs,  is  due  to  the  stimulation  of 
the  skin  causing  reflexly  a  more  rapid  molecular  transformation,  and 
therefore  a  greater  production  of  heat  (Liebermeister),  while  the. 
amount  of  heat  given  off  is  diminished  owing  to  contraction  of  the 
small  cutaneous  vessels  and  the  skin  (Jiirgensen,  Senator,  Speck).  The 
continuous  and  intense  application  of  cold  causes  a  decrease  of  the 
temperature  (Currie),  chiefly  by  conduction,  notwithstanding  that  at 
the  same  time  there  is  a  greater  production  of  heat.  After  a  cold  bath, 
the  temperature  may  be  34°,  32°,  and  even  30°C. 

As  an  after-effect  of  the  great  abstraction  of  heat,  the  temperature  of 
the  body  after  a  time  remains  lower  than  it  was  before  (^'primary  after- 
effect"— Liebermeister);  thus  after  an  hour  it  was — 0"22°C.  in  the 
■  rectum.  There  is  a  ^'■secondary  after-effect"  which  occurs  after  the  first 
after-effect  is  over,  when  the  temperature  rises  (Jiirgensen).  This 
effect  begins  5-8  hours  after  a  cold  bath,  and  is  equal  to  +  0'2°C.  in 
the  rectum.  Hoppe-Seyler  found  that  some  time  after  the  application 
of  heat,  there  was  a  corresponding  lowering  of  the  temperature. 

Taking  Cold. — If  a  rabbit  be  taken  firom  a  surrounding  temperature  of  35°C., 
and  suddenly  cooled,  it  shivers,  and  there  may  be  temporary  diarrhcEa.  After 
two  days,  the  temperature  rises  1"5°C.,  and  albuminuria  occurs.  There  are 
microscopic  traces  of  interstitial  inflammation  in  the  kidneys,  liver,  lungs,  heart, 
and  nerve-sheaths,  the  dilated  arteries  of  the  liver  and  lung  contain  thrombi,  and 
in  the  neighbourhood  of  the  veins  are  accumulations  of  leucocytes.  In  pregnant 
animals,  the  fcetus  shows  the  same  conditions  (Lassar).  Perhaps  the  greatly  cooled 
blood  acts  as  an  iiTitant  causing  inflammation  (Rosenthal). 

Action  of  Frost. — The  continued  application  of  a  high  degree  of  cold  causes  at 
first  contraction  of  the  blood-vessels  of  the  skin  and  its  muscles,  so  that  it  becomes 
pale.  If  continued  paralysis  of  the  cutaneous  Aressels  occurs,  the  skin  becomes  red, 
owing  to  congestion  of  its  vessels.  As  the  passage  of  fluids  through  the  capillaries 
is  rendered  more  difiicult  by  the  cold,  the  blood  stagnates,  and  the  skin  assumes  a 
livid  ap-pearance,  as  the  0  is  almost  completely  used  up.  Thus  the  peripheral 
circulation  is  slowed.  If  the  action  of  the  cold  be  still  more  intense,  the  peripheral 
circulation  stops  completely,  especially  in  the  thinnest  and  most  exposed  organs — 


ARTIFICIAL   LOWERING   OF  THE  TEMPERATURE.  455 

ears,  nose,  toes,  and  fingers.  The  sensory  nerves  are  paralysed,  so  that  there  is 
numbness  and  loss  of  sensibility,  and  the  parts  may  even  be  frozen  through  and 
through.  As  the  slowing  of  the  circulation  in  the  superficial  vessels  gradually 
afifects  other  areas  of  the  circulation,  the  pulmonary  circulation  is  enfeebled,  and 
diminished  oxidation  of  the  blood  occurs,  notwithstanding  the  greater  amount  of 
O  in  the  cold  air,  so  that  the  nerve  centres  are  afi'ected.  Hence,  arise  great  dislike 
to  making  movements  or  any  muscular  effort,  a  painful  sensation  of  fatigue,  a 
peculiar  and  almost  irresistible  desire  to  sleep,  cerebral  inactivity,  blunting  of 
the  sense-organs,  and  lastly,  coma.  The  blood  freezes  at— 3'9°C.,  while  the  juices 
of  the  siiperficial  parts  freeze  sooner.  Too  rapid  movements  of  the  frost-bitten 
parts  ought  to  be  avoided.  Rubbing  with  snow,  and  the  very  gradual  application 
of  heat,  produce  the  best  results.  Partial  death  of  a  part  is  not  unfrequently 
produced  by  the  prolonged  action  of  cold. 


225.  Artificial  Lowering  of  the  Temperature 
in  Animals. 

Phenomena. — The  artificial  cooling  of  warm-hhoded  animals,  by 
placing  them  in  cold  air  or  in  a  freezing  mixture  gives  rise  to  a  series 
of  characteristic  phenomena  (A.  Walther).  If  the  animals  (rabbits) 
are  cooled  so  that  the  temperature  (rectum)  falls  to  18°,  they  suffer 
great  depression  without,  however,  the  voluntary  or  reflex  movements 
being  abolished.  The  pulse  falls  from  100  or  150  to  20  beats  per 
minute,  and  the  blood-pressure  falls  to  several  millimetres  of  Hg.  The 
respirations  are  few  and  shallow.  Suffocation  does  not  cause  spasms 
(Howarth),  the  secretion  of  urine  stops,  and  the  liver  is  congested. 
The  animal  may  remain  for  12  hours  in  this  condition,  and  when  the 
muscles  and  nerves  show  signs  of  paralysis,  coagulation  of  the  blood 
occurs  after  numerous  blood-corpuscles  have  been  destroyed.  The 
retina  becomes  pale,  and  death  occurs  with  spasms  and  the  signs  of 
asphyxia. 

If  the  bodily  temperature  be  reduced  to  17°  and  under,  the 
voluntary  movements  cease  before  the  reflex  acts  (Eichet  and 
Rondeau). 

An  animal  cooled  to  18°C.,  and  left  to  itself,  at  the  same  temperature 
of  the  surroundings,  does  not  recover  of  itself,  but  if  artificial  respira- 
tion be  employed,  the  temperature  rises  10°C.  If  this  be  combined 
with  the  application  of  external  warmth,  the  animals  may  recover  com- 
pletely, even  when  they  have  been  apparently  dead  for  forty  minutes. 
Walther  cooled  adult  animals  to  9°C.,  and  recovered  them  by  artificial 
respii'ation  and  external  warmth;  while  Howarth  cooled  young 
animals  to  5°C.  Mammals,  which  are  born  blind,  and  birds,  which 
come  out  of  the  egg  devoid  of  feathers,  cool  more  rapidly  than  others. 
Morphia,  and  more  so,  alcohol,  accelerate  the  cooling  of  mammals;  hence, 
drunk  men  are  more  liable  to  die  when  exposed  to  cold. 


456  HYBERNATION   AND   USE   OF   COLD. 

Artificial  Cold-Blooded  Condition. — CI.  Bernard  made  the  important 
observation,  that  the  muscles  of  animals  that  had  been  cooled  remained 
irritable  for  a  long  time,  both  to  direct  stimuli  as  well  as  to  stimuli 
applied  to  their  nerves ;  and  the  same  is  the  case  when  the  animals  are 
asphyxiated  for  want  of  0.  An  "  artificial  cold-blooded  condition,"  i.e.,  a 
condition  in  which  warm-blooded  animals  have  a  lower  temperature, 
and  retain  muscular  and  nervous  excitability  (CI.  Bernard),  may  also 
be  caused  in  warm-blooded  animals,  by  dividing  the  cervical  spinal- 
cord  and  keeping  up  artificial  respiration ;  further,  by  moistening  the 
peritoneum  with  a  cool  solution  of  common  salt  (Wegner). 

Hybernation  presents  a  series  of  similar  phenomena.  Valentin  found  that 
hybemating  animals  become  half-awake  when  their  bodily  temperature  is  28°C. ; 
at  18°C.  they  are  in  a  somnolent  condition,  at  Q°  they  are  in  a  gentle  sleep,  and 
at  1  '6''C.  in  a  deep  sleep.  The  heart-beats  and  the  blood-pressure  fall,  the  former 
to  8-10  per  minute.  The  respiratory,  urinary,  and  intestinal  movements  cease 
completely,  and  the  cardio -pneumatic  movement  alone  (p.  110)  sustains  the  slight 
exchange  of  gases  in  the  lungs.  They  cannot  endure  cooling  to  0°C. ;  they  awake 
before  the  temperature  falls  so  low.  Hybernating  animals  may  be  cooled  to  a 
greater  degree  than  other  mammals;  they  give  off  heat  rapidly,  and  they  become 
warm  again  rapidly,  and  even  spontaneously.  New-born  mammals  resemble 
hybernating  animals  more  closely  in  this  respect  than  do  adults. 

Cold-blooded  Animals  may  be  cooled  to  0°.  Even  when  the  blood  has  been 
frozen  and  ice  formed  in  the  lymph  of  the  peritoneal  cavity,  frogs  may  recover. 
In  this  condition  they  appear  to  be  dead,  but  when  placed  in  a  warm  medium 
they  soon  recover.  A  frog's  muscle  so  cooled  will  contract  again  (Kiihne).  The 
germs  and  ova  of  lower  animals,  e.g.,  insects'  eggs,  sur\ave  continued  frost;  and 
if  the  cold  be  moderate,  it  merely  retards  development.  Bacteria  survive  a 
temperature  of— 87° C;  yeast,  even— 100" C  (Frisch). 

Varnislling  the  Skin  causes  a  series  of  similar  phenomena.  The  varnished 
skin  gives  off  a  large  amount  of  heat  by  radiation  (Krieger),  and  sometimes  the 
cutaneous  vessels  are  greatly  dilated  (Laschkewitsch).  Hence  the  animals  cool 
rapidly  and  die,  although  the  consumption  of  0  is  not  diminished.  If  cooling  be 
prevented  (Valentin,  Schiff,  Brunton)  by  warming  them  and  keeping  them  in 
warm  wool,  the  animals  live  for  a  longer  time.  The  blood  post  mortem,  does  not 
contain  any  poisonous  substances,  nor  even  are  any  materials  retained  in  the  blood 
which  can  cause  death,  for  if  the  blood  be  injected  into  other  animals,  these 
remain  healthy.  Varnishing  the  human  skin  does  not  seem  to  be  dangerous— 
(Senator), 

226.  Employment  of  Cold. 

Cold  may  be  applied  to  the  whole  or  part  of  the  surface  of  the  body  in  the 
following  conditions : — 

(a)  By  placing  the  body  for  a  time  in  a  cold  bath  to  abstract  as  much  heat  as 
possible,  when  the  bodily  temperature  in  fever  rises  so  high  as  to  be  dangerous 
to  life.  This  result  is  best  accomplished  and  lasts  longest  when  the  bath  is 
gradually  cooled  from  a  moderate  temperature.  If  the  body  be  placed  at  once  in 
cold  water,  the  cutaneous  vessels  contract,  the  skin  becomes  bloodless,  and  thus 
obstacles  are  placed  in  the  way  of  the  excretion  of  heat.  A  bath  gradually  cooled 
in  this  way  is  borne  longer  (v.  Ziemssen).    The  addition  of  stimulating  substances, 


HISTORICAL  AND   COMPARATIVE.  457 

e.g.,  salts,  which  cause  dilatation  of  the  cutaneous  vessels,  facilitates  the  excretion 
of  heat ;  even  salt-watei'  conducts  heat  better.  If  alcohol  be  given  internally  at 
the  same  time,  it  lowers  the  temperature. 

(6)  Cold  may  be  applied  locally  by  means  of  ice  in  a  bag,  which  causes  contrac- 
tion of  the  cutaneous  vessels  and  contraction  of  the  tissues  (as  in  inflammation), 
while  at  the  same  time  heat  is  abstracted  locally, 

(c)  Heat  may  be  abstracted  locally  by  the  rapid  evaporation  of  volatile  suli- 
stances  (ether,  carbon  disulphide),  which  causes  numbness  of  the  sensory  nerves. 
The  introduction  of  media  of  low  temperature  into  the  body,  respiring  cool  air, 
taking  cold  drinks,  or  the  injection  of  cold  fluids  into  the  intestine  acts  locally, 
and  also  produces  a  more  general  action.  In  applying  cold  it  is  important  to 
notice  that  the  initial  contraction  of  the  vessels  and  the  contraction  of  the  tissues 
are  followed  by  a  stronger  dilatation  and  turgescencc. 

227.  Heat  of  Inflamed  Parts. 

"Calor"  or  heat  is  reckoned  one  of  the  fundamental  phenomena  of  inflamma- 
tion, in  addition  to  rubor  (redness),  tumor  (swelling),  and  dolor  (pain).  But  the 
apparent  increase  in  the  heat  of  the  inflamed  parts  is  not  above  the  temperature 
of  the  blood.  Simon,  in  1S60,  asserted  that  the  arterial  blood  flowing  to  an 
inflamed  part  was  cooler  than  the  part  itself;  but  v.  Barensprung  denies  this,  as 
J.  Hunter  did,  and  so  does  Jacobson,  Bernhardt,  and  Laudien.  The  outer  parts 
of  the  skin  in  an  inflamed  part  are  warmer  than  usual,  owing  to  the  dilatation  of 
the  vessels  (rubor)  and  the  consequent  acceleration  of  the  blood-stream  iu  the 
inflamed  part,  and  owing  to  the  swelling  (tumor)  from  the  presence  of  good  heat- 
conducting  fluids ;  but  the  heat  is  not  greater  than  the  heat  of  the  blood.  It  is 
not  proved  that  an  increased  amount  of  heat  is  produced,  owing  to  increased 
molecular  decompositions  within  an  inflamed  part. 

228.  Historical  and  Comparative. 

According  to  Aristotle,  the  heart  prepares  the  heat  within  itself,  and  sends  it 
along  with  the  blood  to  all  parts  of  the  body.  This  doctrine  prevailed  in  the 
time  of  Hippocrates  and  Galen,  and  occurs  even  in  Cartesius  and  Bartholinus 
(1667,  "flamula  cordis").  The  iatro-mechanical  school  (Boerha.ve,  van  Swieten) 
ascribed  the  heat  to  the  friction  of  the  blood  on  the  walls  of  the  vessels.  The 
iatro-chemical  school,  on  the  other  hand,  sought  the  source  of  heat  in  the  fermenta- 
tions that  arose  from  the  passage  of  the  absorbed  substances  into  the  blood  (van 
Helmont,  Sylvius,  Ettmiiller).  Lavoisier  (1777)  was  the  first  to  ascribe  the  heat 
to  the  combustion  of  carbon  in  the  lungs. 

After  the  construction  of  the  thermometer  by  Galileo,  Sanctorius  (1626)  made 
the  first  thermometric  observations  on  sick  persons,  while  the  first  calorimetric 
observations  were  made  by  Lavoisier  and  Laplace. 

Comparative  observations  are  given  at  §  207,  and  also  under  Hyhernation 
(p.  456). 


Physiology  of  tlie  letabolic  Phenomena 
of  the  Body. 


By  the  term  metabolism  are  meant  all  those  phenomena,  whereby  all 
—even  the  most  lowly — ^living  organisms  are  capable  of  incorporating 
the  substances  obtained  from  their  food  into  their  tissues,  and  making 
them  an  integral  part  of  their  own  bodies.  This  part  of  the  process 
is  known  as  assimilation.  Further,  the  organism  in  virtue  of  its  meta- 
bolism forms  a  store  of  potential  energy,  which  it  can  transform  into 
Tcinetic  energy,  and  which,  in  the  higher  animals  at  least,  appears  most 
obvious  in  the  form  of  muscular  work  and  heat.  The  changes  of 
the  constituents  of  the  tissues,  by  which  these  transformations  of  the 
potential  energy  are  accompanied,  result  in  the  formation  of  excretory 
products,  which  is  another  part  of  the  process  of  metabolism.  The 
normal  metabolism  requires  the  supply  of  food  quantitatively  and 
qualitatively  of  the  proper  kind,  the  laying  up  of  this  food  within  the 
body,  a  regular  chemical  transformation  of  the  tissues,  and  the  pre- 
paration of  the  effete  products  which  have  to  be  given  out  through  the 
excretory  organs. 


229.  General  View  of  the  most  Important 
Substances  used  as  Food. 

Water. 

When  we  remember  that  5  8 '5  per  cent,  of  the  body  consists  of 
water,  that  water  is  being  continually  given  off  by  the  urine  and  fseces, 
as  well  as  through  the  skin  and  lungs,  that  the  processes  of  digestion 
and  absorption  require  water  for  the  solution  of  most  of  the  substances 
used  as  food,  and  that  numerous  substances  excreted  from  the  body 
require  water  for  their  solution — e.g.,  in  the  urine,  the  great  importance 
of  water  and  its  continual  renewal  within  the  organism  are  at  once 
apparent.  As  put  by  Hoppe-Seyler,  all  organisms  live  in  water,  and 
even  in  running-water,  a  saying  which  ranks  with  the  old  saying — 
"  Corpora  non  agunt  nisi  fluida." 

AVater — as  far  as  it  is  not  a  constituent  of  all  fluid  foods — occurs  in 


WATER.  459 

diflferent  forms  as  drink: — (1)  Rain-water,  which  most  closely  resembles 
distilled  or  chemically  pure  water,  always  contains  minute  quantities 
of  COgNHg,  nitrous  and  nitric  acids.  (2)  Spring-water  usually  con- 
tains much  mineral  substance.  It  is  formed  from  the  deposition  of  watery 
vapour  or  rain  from  the  air,  which  permeates  the  soil  containing  much 
COgj  the  CO2  is  dissolved  by  the  water,  and  aids  in  dissolving  the 
alkalies,  alkaline  earths,  and  metals,  which  appear  in  solution  as 
bicarbonates — e.g.,  of  lime  or  iron  oxide.  The  water  is  removed  from 
the  spring  by  proper  mechanical  appliances,  or  it  bubbles  up  on  the 
surface  in  the  form  of  a  "  spring."  (3)  The  running-water  of  rivers 
usually  contains  much  less  mineral  matter  than  spring-water.  Spring- 
water  floating  on  the  surface  rapidly  gives  off  its  COg,  whereby  many 
substances — e.g.,  lime — are  thrown  out  of  solution,  and  deposited  as 
insoluble  precipitates. 

Gases. — Spring-water  contains  little  0,  but  much  CO2,  which  latter 
gives  to  it  its  fresh  taste.  Hence,  vegetable  organisms  flourish  in 
spring-water,  while  animals  requiring,  as  they  do,  much  0,  are 
but  poorly  represented  in  such  water.  Water  flowing  freely  gives  up 
CO2,  and  absorbs  0  from  the  air,  and  thus  aflbrds  the  necessary  con- 
ditions for  the  existence  of  fishes  and  other  marine  animals.  Eiver- 
water  contains  ^^  -  -^-q  of  its  volume  of  absorbed  gases,  which  may  be 
expelled  by  boiling  or  freezing. 

Drinking-water  is  chiefly  obtained  from  springs.  River-water,  if 
used  for  this  purpose,  must  be  filtered  to  get  rid  of  mechanically 
suspended  impurities.  For  household  purposes  a  charcoal  filter  may 
be  used,  as  the  charcoal  acts  as  a  disinfectant.  Alum  has  a  remarkable 
action ;  if  0 '00 01  per  cent,  be  added,  it  makes  turbid  water  clear. 

Investigation  of  Drinking-water. — Drinking-water,  even  in  a  thick 
layer,  ought  to  be  completely  colourless,  not  turbid,  and  tuitliout  odour. 
Any  odour  is  best  recognised  by  heating  it  to  50°C.,  and  adding  a 
little  caustic  soda.  It  ought  not  to  be  too  hard — i.e.,  it  ought  not  to 
contain  too  much  lime  (and  magnesia)  salts. 

By  the  term  "  degree  of  hardness"  of  a  water  is  meant  the  unit  amount  of 
lime  (and  magnesia)  in  100,000  parts  of  water ;  a  water  of  20°  of  hardness  con- 
tains 20  parts  of  lime  (calcium  oxide)  combined  with  CO2,  sulphuric,  or  hj'dro- 
chloric  acids  (the  small  amount  of  magnesia  may  be  neglected).  A  good  drinking 
water  ought  not  to  exceed  20°  of  hardness.  The  hardness  is  determined  by  titrating 
the  water  with  a  standard  soap  solution,  the  result  being  the  formation  of  a 
scum  on  the  surface. 

The  hardness  of  unboiled  water  is  called  its  total  hardness,  while  that  of  boiled 
water  is  called  permanent  hardness.  Boiling  drives  off  the  CO2,  and  precipitates 
the  calcium  carbonate,  so  that  the  water  at  the  same  time  becomes  softer. 

The  presence  of  sulphuric  acld,  or  sulphates,  is  determined  by  the  water 
becoming  turbid  on  adding  a  solution  of  bariiim  chloride  and  hydrochloric  acid. 

Chlorine  occurs  in  small  amount  in  pure  spring  water,  but  when  it  occurs  there 


460  SALTS   AND   OTHER   SUBSTANCES  IN   WATER. 

in  large  amount — apart  from  its  being  derived  from  saline  springs,  near  the  sea  or 
manitfactories — we  may  conclude  that  the  water  is  contaminated  from  water- 
closets  or  dunghills,  so  that  the  estimation  of  chlorine  is  of  importance.  For  this 
purpose  use  a  solution,  A,  of  17  grms.  of  crystallised  silver  nitrate  in  1  litre  of 
distilled  water;  1  cubic  centimetre  of  this  solution  precipitates  3  "55  milligrammes  of 
chlorine  as  silver  chloride.  Use  also  B,  a  cold  saturated  solution  of  neutral 
potassium  chromate.  Take  50  cubic  centimetres  of  the  water  to  be  investigated, 
and  place  it  in  a  beaker,  add  to  it  2-3  drops  of  B,  and  allow  the  fluid  A  to  run 
into  it  from  a  burette  until  the  white  precipitate  first  formed  remains  red,  even 
after  the  fluid  has  been  stirred.  Multiply  the  number  of  cubic  centimetres  of  A 
used  by  7'1,  and  this  will  give  the  amount  of  chlorine  in  100,000  parts  of  the 
water.  Example — 50  c.cmtr.  requires  2 '9  c.cmtr.  of  the  silver  solution,  so  that 
100,000  parts  of  the  water  contain  2*9  x  7'1  =  20'59  parts  chlorine  (Kubel,  Tiemann). 
Good  water  ought  not  to  contain  more  than  15  milligrammes  of  chlorine  per  litre. 

The  presence  of  lime  may  be  ascertained  by  acidulating  50  cubic  centimetres  of 
the  water  with  HCl  and  adding  ammonia  in  excess,  and  afterwards  adding 
ammonia  oxalate  ;  the  white  precipitate  is  lime  oxalate.  According  to  the  degree 
of  turbidity  we  judge  whether  the  water  is  "soft"  (poor  in  lime),  or  "hard" 
(rich  in  lime). 

Magnesia  is  determined  by  taking  the  clear  fluid  of  the  above  operation,  after 
removing  the  precipitate  of  lime  and  adding  to  it  a  solution  of  sodium  phosphate 
and  some  ammonia  ;  the  crystalline  precipitate  which  occurs  is  magnesia. 

The  more  feeble  all  these  reactions  are  which  indicate  the  presence  of  sulphuric 
acid,  chlorine,  lime,  and  magnesia,  the  better  is  the  water.  In  addition,  good 
water  ought  not  to  contain  more  than  traces  of  nitrates,  nitrites,  or  compounds  of 
ammonia,  as  their  presence  indicates  the  decomposition  of  nitrogenous  organic 
substances. 

For  nitric  acid,  take  100  cubic  centimetres  of  water  acidulated  with  2  to  3 
drops  of  concentrated  sulphuric  acid,  add  several  pieces  of  zinc  together  with  a  solu- 
tion of  potassium  iodide,  and  starch  solution— a  blue  colour  indicates  nitric  acid. 
The  following  test  is  very  delicate : — Add  to  half  a  drop  of  water  in  a  capsule  2 
drops  of  a  watery  solution  of  Brucinum  sulphuricum,  and  afterwards  several  drops 
of  concentrated  sulphuric  acid ;  a  rose-red  colouration  indicates  the  presence  of 
nitric  acid. 

The  presence  of  nitrOUS  acid  is  ascertained  by  the  blue  colouration  which 
results  from  the  addition  of  a  solution  of  potassium  iodide,  and  solution  of  starch 
after  the  water  has  been  acidulated  with  sulphuric  acid. 

Compounds  of  ammonia  are  detected  by  Nessler's  reagent,  which  gives  a 
yellow  or  reddish  colouration  when  a  trace  of  ammonia  is  present  in  water ;  while 
a  large  amount  of  these  compounds  gives  a  brown  precipitate  of  the  iodide  of 
mercury  and  ammonia. 

The  contamination  of  water  by  decomposing  animal  substance  is  determined  by 
the  amount  of  N  it  contains.  In  most  cases  it  is  sufficient  to  determine  the 
amount  of  nitric  acid  present.  For  this  purpose  we  require  (A)  a  solution  of  l"87l 
grms.  potassium  nitrate  in  1  litre  distilled  water — 1  cubic  centimetre  contains  1 
milligramme  nitric  acid ;  (B)  a  dilute  solution  of  indigo,  which  is  prepared  by  rubbing 
together  1  part  of  pulverised  indigotin  with  6  parts  H2SO4,  and  allowing  the 
deposit  to  subside,  when  the  blue  fluid  is  poured  into  40  times  its  volume  of  dis- 
tilled water  and  filtered.  This  fluid  is  diluted  with  distilled  water  until  a  layer, 
12-15  mm.  in  thickness  begins  to  be  transparent. 

To  test  the  activity  of  B,  place  1  cubic  centimetre  of  A  in  24  cubic  centimetres 
water,  add  some  common  salt  and  50  cubic  centimetres  concentrated  sulphuric 
acid,  and  allow  B  to  flow  from  a  burette  into  this  mixture  until  a  faint  green 
colour  is  obtained.  The  number  of  cubic  centimetres  of  B  used  correspond  to  1 
milligramme  of  nitric  acid. 


MAIHaURY  GLANDS.  461 

25  cubic  centimetres  of  the  water  to  be  investigated  are  mixed  with  50  cubic 
centimetres  of  concentrated  H2SO4,  and  titrated  with  B  until  a  green  colour  is 
obtained.  This  process  must  be  repeated,  and  on  the  second  occasion  the  solution 
B  must  be  allowed  to  flow  in  at  once,  when  usually  somewhat  more  indigo  solution 
is  required  to  obtain  the  green  solution.  The  number  of  cubic  centimetres  of  B 
(corresponding  to  the  strength  of  B,  as  determined  above),  indicates  the  amount  of 
nitric  acid  present  in  25  c.cmtr.  of  the  water  investigated.  As  much  as  10  milli- 
grammes nitric  acid  have  been  found  in  spring- water  (Marx,  Trommsdorff ). 

Sulphuretted  Hydrogen  is  recognised  by  its  odour  ;  also  by  a  piece  of  blotting- 
paper  moistened  with  alkaline  solution  of  lead  becoming  brown,  when  it  is  held 
over  the  boiling  water.  If  it  occurs  as  a  compound  in  the  water,  sodium  nitro- 
prusside  gives  a  reddish  violet  colour. 

It  is  of  the  greatest  importance  that  drinking  water  should  be  free,  from  the 
presence  of  orgauic  matter  in  a  state  of  decomposition.  Organic  matter  in  a 
state  of  decomposition,  and  the  organisms  therewith  associated,  when  introduced 
into  the  body,  may  give  rise  to  fatal  maladies,  e.g.,  cholera  and  typhoid  fever.  This 
is  the  case  when  the  water-supply  has  been  contaminated  from  water  which  has 
percolated  from  water-closets,  privies,  and  dmig-pits.  The  j)i'esence  of  organic 
matter  may  he  detected  thu^ — (1)  A  considerable  amount  of  the  water  is  evaporated 
to  dryness  in  a  porcelain  vessel,  if  the  residue  be  heated  again  a  brown  or  black 
colour  indicates  the  presence  of  a  considerable  amount  of  organic  matter  ;  and  if  it 
contain  N,  there  is  an  odour  of  ammonia.  Good  water  treated  in  this  way  gives 
only  a  light-bro^Ti.  The  presence  of  micro-organisms  may  be  determined  microsco- 
pically after  evaporating  a  small  quantity  of  the  water  on  a  glass-slide.  (2)  The 
addition  oi  potassio-gold  chloride  added  to  the  water  gives  a  black  frothy  precipitate 
after  long  standing.  (3)  A  solution  of  jiotassium  2)ermanganate,  added  to  the  water 
in  a  covered  jar,  gradually  becomes  decolourised,  and  a  brownish  precipitate  is 
formed. 

Water  containmg  much  organic  matter  should  7iever  be  used  as  drinking  water, 
and  this  is  especially  the  case  when  there  is  an  epidemic  of  typhoid  fever,  cholera, 
or  diarrhcea.  In  all  such  circumstances,  the  water  ought  to  be  boiled  for  a  long 
time,  whereby  the  organic  germs  are  killed.  The  insipid  taste  of  the  water  after 
boiling  may  be  corrected  by  adding  a  little  sugar  or  lime  juice. 


230.  Structure  and  Secretion  of  the  Mammary 

Glands. 

About  20  galactoferous  ducts  open  singly  upon  the  surface  of  the  nipple.  Each 
of  these,  just  before  it  opens  on  the  surface,  is  provided  with  an  oval  dilatation — 
the  sinus  lacteus.  'X^Tien  traced  into  the  gland,  the  galactoferous  ducts  divide  like 
the  branches  of  a  tree,  and  a  large  branch  of  the  duct  passes  to  each  lobe  of  the 
gland,  all  the  lobes  being  held  together  by  loose  connective-tissue.  Only  during 
lactation  do  all  the  fine  terminations  of  the  ducts  communicate  with  the  globular 
glandular  acini.  Every  gland  aci7ius  consists  of  a  membrana  propria,  surrounded 
externally  with  a  net-work  of  branched  connective-tissue  corpuscles,  and  lined 
internally  witha  somewhat  flattened  polyhedral  layer  of  nucleated  secretory  cells  (Fig. 
171.)  The  size  of  the  lumen  of  the  acini  depends  upon  the  secretory  activity  of  the 
glands  ;  when  it  is  large  it  is  tilled  with  milk  containing  numerous  refi-active  fatty 
granules.  The  milk-ducts  consist  of  fibrillar  comiective-tissue.  Some  fibres  are 
arranged  longitudinally,  but  the  chief  mass  are  disposed  circularly,  and  are  permeated 
externally  with  elastic  fibres,  while  in  the  finer  ducts,  there  is  a  membrana  propria 
continuous  with  that  of  the  gland  acini.  The  ducts  are  lined  by  cylindrical 
epithelium. 


462 


STRUCTURE    OF   THE   MAJNQIA. 


During  the  first  few  days  after  delivery,  the  breasts  secrete  a  small  amount  of 
milk  of  greater  consistence,  and  of  a  yellow  colour — the  colostruin — in  which 

large  cells  filled  with  fatty  granules  occur — 
the  colostrum-corpuscles.  Sometimes  a  nucleus 
is  observable  within  them,  and  rarely  they 
exhibit  amoeboid  movements  (Fig.  172,  c,  d,  e). 
The  regular  secretion  of  milk  begins  after  3-4  days. 
It  was  formerly  supposed  that  the  cells  of  the 
acini  underwent  a  fatty  degeneration,  and  thus 
produced  the  fatty  granules  of  the  milk.  It  is 
more  probable,  from  the  observations  of  Strieker, 
Schwarz,  Partsch  and  Heidenhain,  that  the  cells 
of  the  acini  manufacture  the  fatty  granules,  and 
their  protoplasm  eliminates  them,  at  the  same 
time  forming  the  clear  fluid  part  of  the  milk. 


Fig.  171. 
Acini  of  the  manunary  gland 


of  a  sheep  during  lactation — 
a,  membrana  propria;  b, 
secretory  epithelium. 


Changes  during  Secretion. — Partsch  and 
Heidenhain  found  that  the  secretory  cells 
in  the  passive  non-secreting  gland  (Fig.  172,  I)  were  flat,  polyhedral, 
and  nni-nucleated,   whilst  the   secreting   cells    (Fig.   II)    often   con- 


IT 


1/  o°°o'^ 


Fig.  172. 

I — Inactive  acinus  of  the  mamma.     II — During  the  secretion  of  milk  ;  a,  h,  milk- 
globules  ;  c,  d,  e,  colostrum-corpuscles  ;  /,  pale  cells  (bitch). 

tained  several  nuclei,  were  more  albuminous,  higher,  and  cylindrical 
in  form.  The  edge  of  the  cell  directed  towards  the  lumen  of  the 
acinus  undergoes  characteristic  changes  during  secretion.  Fatty 
granules  are  formed  in  this  part  of  the  cell,  and  are  afterwards  ex- 
truded. The  decomposed  portion  of  the  cell  is  dissolved  in  the  milk, 
and  the  fatty  granules  become  free  as  milk-globules.  (Fig.  II,  a).  If 
nuclei  are  present  in  that  part  of  the  cell  which  is  broken  up,  they  also 
pass  into  the  milk  and  give  rise  to  the  presence  of  nuclein  in  the 
secretion. 

Besides  the  milk -globules  and  colostrum-corpuscles,  Rauber  has  found  leucocytes 
undergoing  fatty  degeneration  and  single  pale  cells  (/).  Occasionally  milk-globules 
are  found  with  traces  of  the  cell-substance  adhering  to  their  surface  (6). 

Formation  of  Milk. — Concerning  the  formation  of  the  individual  constituents 


STRUCTURE   OF   THE   MAMMA.  4G3 

of  milk,  H.  Thierfelder,  who  digested  fresh  mammary  glands  directly  after  death, 
found  that  during  the  digestion  of  the  glands  at  the  temperature  of  the  body,  a 
reducing  substance,  probably  lactose,  was  formed  by  a  process  of  fermentation. 
The  mother  substance  (saccharogen)  is  soluble  in  water,  but  not  in  alcohol  or  ether, 
is  not  destroyed  by  boiling,  and  is  not  identical  with  glycogen.  The  ferment  which 
forms  the  lactose  is  connected  with  the  gland-cells — it  does  not  pass  into  the 
milk,  nor  into  a  watery  extract  of  the  gland.  During  the  digestion  of  the  mammary 
glands,  at  the  temperature  of  the  body,  casein  is  formed,  probably  from  serum- 
albumin,  by  a  process  of  fermentation.     This  ferment  occurs  in  the  milk. 

The  nipple  and  its  areola  are  characterised  by  the  presence  of  pigment — more 
abundant  during  pregnancy — in  the  rete  Malpighii  of  the  skin,  and  by  large  papillae 
in  the  cutis  vera.  Some  of  the  papillae  contain  touch-corpuscles.  Numerous  non- 
striped  muscular  fibres  surround  the  milk-ducts  in  the  deep  layers  of  the  skin  and 
in  the  subcutaneous  tissue,  which  contains  no  fat.  These  muscular  fibres  can  be 
traced  folloAving  a  longitudinal  course  to  the  termination  of  the  ducts  on  the  surface. 
The  small  glands  of  Montgomery,  which  occur  on  the  areola  during  lactation,  are 
small  milk-glands,  each  with  a  special  duct  opening  on  the  surface  of  the  elevation. 

Arteries  proceed  from  several  sources  to  supply  the  mamma,  but  their  branches 
do  not  accompany  the  mUk-ducts  ;  the  gland  acini  ai'e  each  surrounded  by  a  net- 
work of  capillaries,  which  communicate  with  those  of  adjoining  acini  by  small 
arteries  and  veins.  The  veins  of  the  areola  are  arranged  in  a  cii'cle  (circulus 
Halleri).  The  nerves  are  derived  from  the  supraclavicular,  and  the  II-IV-VI 
intercostals  ;  they  proceed  to  the  skin  over  the  gland,  to  the  very  sensitive  nipple, 
to  the  blood-vessels  and  non-striped  muscle  of  the  nipple,  and  to  the  gland  acini, 
where  their  mode  of  termination  is  stUl  unknown.  Lymphatics  surround  the 
alveoli,  and  they  are  often  full.  The  milk  appears  to  be  jjrepared  from  the  lymph 
contained  in  the  lymphatics  surrounding  the  acini. 

The  comparative  anatomy  of  the  mamma. — The  rodents,  insectivora,  and  car- 
nivora,  have  10  to  12  teats,  while  some  of  them  have  only  4.  The  pachydermata  and 
ruminantia  have  2-4  abdominal  teats,  the  Avhale  has  2  near  the  vulva.  The  apes, 
bats,  vegetable-feeding  whales,  elephants,  and  sloths  have  2,  like  man.  In  the 
marsupials  the  tubes  are  arranged  in  gi'oups,  which  open  on  a  patch  of  skin  devoid 
of  hair  \\dthout  any  nipple.  The  young  animals  remain  within  the  mother's  pouch, 
and  the  milk  is  expelled  into  their  mouths  by  the  action  of  a  muscle — the  com- 
pressor mammae. 

The  development  of  the  human  mamma  begins  in  both  sexes  during  the  third 
month ;  at  the  fourth  and  fifth  months,  a  few  simple  tubular  gland-ducts  are 
arranged  radially  around  the  position  of  the  future  nipple,  which  is  devoid  of  hair. 
In  the  new-born  child  the  ducts  are  branched  twice  or  thrice,  and  are  provided 
with  dilated  extremities,  the  future  acini.  Up  to  the  12th  year  in  both  sexes,  the 
ducts  continue  to  divide  dendritically,  but  without  any  proper  acini  being  formed. 

In  the  girl  at  puberty  the  ducts  branch  rapidly  ;  but  the  acini  are  formed  only  at 
the  periphery  of  the  gland,  while  during  pregnancy,  acini  are  also  formed  in  the 
centre  of  the  gland,  while  the  connective-tissue  at  the  same  time  becomes  some- 
what more  opened  out.  At  the  climactiric  period,  or  menopause,  all  the  acini  and 
numerous  fine  milk-ducts  degenerate.  In  the  adult  male,  the  gland  remains 
in  the  non-developed  infantile  condition.  Accessory  or  supernumerary  glands 
upon  the  breast  and  abdomen  are  not  uncommon,  sometimes  the  mamma  occurs  in 
the  axilla,  on  the  back,  over  the  acromion  process,  or  on  the  leg.  A  slight  secre- 
tion of  milk  in  a  newly-bom  infant  is  normal. 

During  the  evacuation  of  the  milk  (500-1500  cubic  centimetres  daily),  there  is 
not  only  the  mechanical  action  of  sucking,  but  also  the  activity  of  the  gland  itself. 
This  consists  in  the  erection  of  the  nipple,  whereby  its  non-striped  muscular  fibres 
compress  the  sinuses  on  the  milk-ducts,  and  empty  them,  so  that  the  mUk  may  flow 
out  in  streams.     The  gland  acini  are  also  excited  to  secretion  refiexly  by  the  atim- 


464  MILK  AND   ITS   PREPARATIONS. 

ulation  of  the  sensory  nerveS  of  the  nipple.  The  vessels  of  the  gland  are  dilated, 
and  there  is  a  copious  transudation  into  the  gland,  the  transuded  fluid  being 
manufactured  into  milk  under  the  influence  of  the  secretory  protoplasm.  The 
amount  of  secretion  depends  upon  the  blood-pressure  (ROhrig).  During  sucking, 
not  only  is  the  milk  in  the  gland  extracted,  but  new  milk  is  formed,  owing  to  the 
accelerated  secretion.  Emotional  disturbances — anger,  fear,  &c. — arrest  the  secre- 
tion. Laffont  found  that  stimulation  of  the  mammary  nerve  (bitch)  caused 
erection  of  the  teat,  dilatation  of  the  vessels,  and  secretion  of  milk.  After  section 
of  the  cerebro-spinal  nerves  going  to  the  mamma,  Eckhard  observed  that  erection 
of  the  teat  ceased,  although  the  secretion  of  milk  in  a  goat  was  not  interrupted. 
The  rarely  observed  galactorrhcea  is  perhaps  to  be  regarded  as  a  paralytic  secre- 
tion analogous  to  the  paralytic  secretion  of  saliva.  Heidenhain  and  Partsch  found 
that  the  secretion  (bitch)  was  increased  by  injecting  strychnine  or  curara  after 
section  of  the  nerves  of  the  gland.  The  "milk-fever,"  which  accompanies  the 
first  secretion  of  milk,  probably  depends  on  stimulation  of  the  vaso-motor  nerves, 
but  this  condition  must  be  studied  in  relation  with  the  other  changes  which 
occur  within  the  pelvic  cavity  after  birth.  [Some  substances,  such  as  atropin, 
arrest  the  secretion  of  milk.] 


231.  Milk  and  its  Preparations. 

Milk  represents  a  complete  or  typical  food  in  which  all  the  con- 
stituents necessary  for  maintaining  the  life  and  growth  of  the  body 
are  present.  To  every  10  parts  of  proteids  there  are  10  parts  fat  and 
20  parts  sugar.  Kelatively  more  fat  than  albumin  is  absorbed  from 
the  milk  (Rubner) ;  while  a  part  of  both  is  excreted  in  the  faeces, 

Characters. — Milk  is  an  opaque,  bluish-white  fluid  with  a  sweetish 
taste  and  a  characteristic  odour,  probably  due  to  the  peculiar  volatile 
substances  derived  from  the  cutaneous  secretions  of  the  glands,  and 
it  has  a  specific  gravity  of  1026-1035  (Radenhausen).  When  it 
stands  for  a  time,  numerous  milk-globules,  butter-globules,  or  cream, 
collect  on  its  surface,  under  which  there  is  a  watery  bluish  fluid. 
Human  milk  is  always  alkaline,  cow's  milk  may  be  alkaline,  acid  or 
amphoteric ;  while  the  milk  of  carnivora  is  always  acid. 

MUk-Globules. — When  milk  is  examined  microscopically,  it  is  seen 
to  contain  numerous  small  highly  refractive  oil-globules,  floating  in  a 
clear  fluid — the  milk-plasma  (Fig.  172,  a,  5,);  while  colostrum-corpuscles 
and  epithelium  from  the  milk-ducts  are  not  so  numerous.  The  white 
colour  and  opacity  of  the  milk  are  due  to  the  presence  of  the  milk- 
globules  which  reflect  the  light ;  the  globules  consist  of  a  fat,  or  butter, 
surrounded  with  a  very  thin  envelope  of  casein.  If  acetic  acid  be 
added  to  a  microscopic  preparation  of  milk,  this  caseous  envelope 
is  dissolved,  the  fatty  granules  are  liberated,  and  they  run 
together  to  form  irregular  masses.  If  cow's  milk  be  shaken  with 
caustic  potash,  the  casein  envelopes  are  dissolved,  and  if  ether  be 
added,  the  milk  becomes  clear  and  transparent,  as  the  ether  dissolves 


FATS  AND   PLASMA   OF  MILK.  465 

out  all  the  fatty  particles  in  the  solution.  Ether  cannot  extract 
the  fat  from  cow's  milk  until  acetic  acid  or  caustic  potash  is  added  to 
liberate  the  fats  from  their  envelopes;  but  shaking  with  ether  is 
sufficient  to  extract  the  fats  from  human  milk  (Radenhausen).  Some 
observers  deny  that  an  envelope  of  casein  exists,  and  according  to 
them  milk  is  a  simple  emulsion,  kept  emulsionised  owing  to  the  colloid 
swollen  up  casein  in  the  milk-plasma.  The  treatment  of  milk  with 
potash  and  ether  makes  the  casein  unable  any  longer  to  preserve  the 
emulsion  (Soxhlet). 

The  fats  of  the  milk-globules  are  the  triglycerides  of  stearic,  palmitic, 
myristic,  oleic,  arachinic  (butinic),  capric,  caprylic,  caproic,  and  butyric  acids, 
with  traces  of  acetic  and  formic  acids  (Heintz),  and  cholesterin  (Schmidt-Miilheim). 
When  milk  is  beaten  or  stirred  for  a  long  time  (i.e.,  churned),  the  fat  of  the 
milk-globules  is  ultimately  obtained  in  the  form  of  butter,  owing  to  the  rupture 
of  the  envelopes  of  casein. 

Butter  is  soluble  in  alcohol  and  ether,  and  it  is  clarified  by  heat  {60°C.),  or 
by  washing  in  water  at  40°C.  When  allowed  to  stand  exposed  to  the  air  it 
becomes  rancid,  owing  to  the  glycerine  of  the  neutral  fats  being  decomposed  by 
fungi  into  acrolein  and  formic  acid,  while  the  volatile  fatty  acids  give  it  its  rancid 
odour. 

The  milk-plasma,  obtained  by  filtration  through  clay  filters  or  mem- 
branes, is  a  clear,  slightly  opalescent  fluid,  and  contains  casein  (§  '^49, 
III,  3),  serum-albumin  (p.  49),  and  to  a  less  extent  a  body  resembling 
albumin  {ladoprotein — Millon,  Liebermann) ;  galactin,  albuminose,  and 
globulin;  peptone  (0'13  per  cent.);  nuclein,  diastatic  ferment  (in 
human  milk — Bechamp).  Milk-sugar  (§  252),  a  carbohydrate  resemb- 
ling dextrin  (Ritthausen),  (?■  lactic  acid),  lecithin,  urea,  extractives ; — 
sodic  and  potassic  chlorides,  alkaline  phosphates,  calcium  and  mag- 
nesium sulphates,  alkaline  carbonates,  traces  of  iron,  fluorine,  and 
sHica;  COoN,  0. 

When  milk  is  boiled  the  albumin  coagulates,  while  the  surface  also 
becomes  covered  with  a  thin  scum  or  layer  of  casein,  which  has 
become  insoluble. 

When  milk  is  filtered  through  fresh  animal  membranes  (Hoppe-Seyler),  or 
through  a  clay  filter,  the  casein  does  not  pass  through  (Helmholtz,  Zahn,  Kehrer), 
while  burned  pulverised  clay  and  animal  charcoal  also  attract  the  casein  (Dupr6 
and  Hermann). 

The  coagulation  of  milk  depends  upon  the  coagulation  of  its  casein.  In  milk, 
casein  is  combined  with  calcium  phosphate,  which  keeps  it  in  solution;  acids 
which  act  on  the  calcium  phosphate  cause  coagulation  of  the  casein  (acetic  and  tar- 
taric acids  in  excess  redissolve  it).  All  acids  do  not  coagulate  human  milk  (Biedert). 
It  is  coagulated  by  two  or  more  drops  of  hydrochloric  acid  (0"1  per  cent.)  or  acetic 
acid  (0*2  per  cent.).  The  spontaneous  coagulation  of  milk  after  it  has  stood  for  a 
time,  especially  ia  a  warm  place,  is  due  to  the  formation  of  lactic  acid,  which  is 

30 


466  COMPOSITION   OF  MILK. 

formed  from  the  milk-sugar  in  the  milk  by  the  action  of  bacterium  lacticum  [which 
is  introduced  from  without  (Pasteur,  Cohn,  Lister)].  It  changes  the  neutral  alka- 
line phosphate  into  the  acid  phosphate,  takes  the  casein  from  the  calcium  phosphate, 
and  precipitates  the  casein  (p.  373).  The  ferment  may  be  isolated  by  means  of 
alcohol. 

Hennet,  which  contains  a  special  ferment,  coagulates  milk  with  an  alkaline 
reaction  (sweet  whey).  This  ferment  decomposes  the  casein  into  the  precipitated 
cheese,  and  also  into  the  slightly  soluble  whey-albumin  (Hammarsten,  KOster),  so 
that  the  coagulation  by  rennet  is  a  process  quite  distinct  from  the  coagulation  of 
milk  by  the  gastric  and  pancreatic  juices.  When  the  milk  is  coagulated  we  obtain 
the  curd,  consisting  of  casern  with  some  milk-globules  entangled  in  it ;  the  whey 
contains  some  soluble  albumin  and  fat,  and  the  great  proportion  of  the  salts  and 
milk-sugar,  together  with  lactic  acid. 

Boiling  (by  killing  all  the  lower  organisms),  sodium  bicarbonate  (xTnTTr)*  amnionia, 
salicylic  acid  isistTs)}  glycerine,  and  ethereal  oil  of  mustard  prevent  the  spon-. 
taneous  coagulation.  Fresh  milk  makes  tincture  of  guaiacum  blue,  but  boiled 
milk  does  not  do  so  (Schacht,  C.  Arnold).  When  milk  is  exposed  to  the  air  for  a 
long  time,  it  gives  off  CO2,  and  absorbs  0  ;  the  fats  are  increased  (?  owing  to  the 
development  of  fungi  in  the  milk),  and  so  are  the  alcoholic  and  ethereal  extracts, 
from  the  decomposition  of  the  casein  (Hoppe-Seyler,  Kemmerich).  According  to 
Schmidt-Mulheim,  some  of  the  casein  becomes  convei'ted  into  peptone,  but  this 
occurs  only  in  unboiled  milk. 

Composition. — 100  parts  of  milk  contain — 

Human. 

Water,      .....  87 '24— 90-58 
Solids, 9-42— 12-39 

Casein, ^■^^■~  ^"^^  I  1-90-2-21  ]- 

Albumin,    .     .     ...  ...         ...    J                      / 

Butter, 2  ■67—  4-30 

Milk-sugar,     .     .     .  3-15—  6-09 

Salts 0-14—  0-28 

Human  milk  contains  less  albumin,  which  is  more  soluble  than  the  albumin  in 
the  milk  of  animals, 

Colostruill  contains  much  serum-albumin,  and  very  little  casein,  while  all  the 
other  substances,  and  especially  the  fats,  are  more  abundant. 

Gases. — Pfliiger  and  Setschenow  found  in  100  vols,  of  milk  5-01-7-60  CO2  ; 
0-09-0-32  0;  0-70-1-41  N,  according  to  volume.  Only  part  of  the  CO2  is  expelled 
by  phosphoric  acid. 

Salts. — The  potash  salts  (as  in  blood  and  muscle)  are  more  abundant  than  the 
soda  compounds,  while  there  is  a  considerable  amount  of  calcium  phosphate, 
which  is  necessary  for  forming  the  bones  of  the  infant.  Wildenstein  found  in  100 
parts  of  the  ash  of  human  milk— sodium  chloride,  10-73;  potassium  chloride,  26-33; 
potash,  21-44;  lime,  18-78;  magnesia,  0-87;  phosphoric  acid,  19;  ferric  phosphate, 
0-21 ;  sulphuric  acid,  2-64 ;  silica  traces.  The  amount  of  salts  present  is  affected 
by  the  salts  of  the  food. 

Conditions  Influencing  the  Composition.— The  more  frequently  the  breasts 

are  emptied,  the  richer  the  milk  becomes  in  casein.  The  last  milk  obtained  at  any 
time  is  always  richer  in  butter,  as  it  comes  from  the  most  distant  part  of  the 
gland— viz.,  the  acini  (Reiset,  Heynsius,  Forster,  de  Leon).    Some  substances  are 


Oowr 

Goat, 

Ass. 

86-23 

86-85 

89-01 

13-77 

13-52 

10-99 

3-23 
0-50 

2-53 
1-26 

} 

3-57 

4-50 

4-34 

1-85 

4-93 
0-6 

3-78 
0-65 

\ 

5  05 

TESTS   FOR   MILK.  467 

diminished  and  others  increased  in  amount,  according  to  the  time  after  delivery. 
The  following  are  increased: — Until  the  2nd  month  after  delivery,  casern  and  fat; 
until  the  5th  month,  the  salts  (which  diminish  progressively  from  this  time 
onwards);  from  S-lOth  months,  the  sugar.  The  foUowmg  are  diminished  .-—From 
10-24th  months,  casein;  from  5-Cth  and  10-llth  months,  fat;  during  1st  month, 
the  sugar ;  from  the  5th  month,  the  salts. 

[That  cow's  milk  is  influenced  by  the  pasture  and  food  is  well-known.  Turnip 
as  food  give  a  peculiar  odour,  taste,  and  flavour  to  milk,  and  so  do  the  fragrant 
grasses.  The  mental  state  of  the  nurse  influences  the  quantity  and  quality  of  the 
milk,  while  many  substances  given  as  medicines  reappear  in  the  milk,  such  as 
dill,  copaiba,  conium,  aniseed,  garlic,  potassium  iodide,  arsenic,  mercury,  opium, 
rhubarb,  or  its  active  principle,  and  the  cathartic  principle  of  senna.  Jaborandi  is 
the  nearest  approach  to  a  galactagogue,  but  its  action  is  temporary.  Atropin  is  a 
true  anti-galactagogue.  The  composition  of  the  milk  may  be  affected  by  using 
fatty  food,  by  the  use  of  salts,  and  above  all  by  the  diet  (Dolan).] 

[Milk  may  be  a  vehicle  for  communicating  disease — by  direct  contamination 
from  the  water  used  for  adulteration  or  cleansing ;  by  the  milk  absorbing 
deleterous  gases;  by  the  secretion  being  altered  in  diseased  animals.] 

The  greater  the  amount  of  milk  that  is  secreted  (woman),  the  more  casein  and 
sugar,  and  the  less  butter  it  contains.  The  milk  of  a  primipara  is  less  watery. 
Rich  feeding,  especially  proteids  (small  amount  of  vegetable  food),  increase  the 
amount  of  milk  and  the  casein,  sugar,  and  fat  in  it;  a  large  amount  of  carbo- 
hydrates (not  fats)  increases  the  amount  of  sugar. 

If  other  than  human  milk  has  to  be  used,  ass's  milk  most  closely  resembles 
human  milk.  Cow's  milk  is  best  when  it  contains  plenty  fatty  matters — it  must 
be  diluted  with  its  own  volume  of  water  at  first,  and  a  little  milk-sugar 
added.  The  casein  of  cow's  milk  diff'ers  qualitatively  from  that  of  human  milk 
(Biedert);  its  coagixlated  flocculi  or  curd  are  much  coarser  than  the  fine  curd  of 
human  milk,  and  they  are  only  |  dissolved  by  the  digestive  juices,  while  human  milk 
is  completely  dissolved.  Cow's  milk  when  boiled  is  less  digestible  than  unboiled 
(E.  Jessen). 

Milk  ought  not  to  be  kept  in  zinc  vessels  owing  to  the  formation  of  zinc 
lactate. 

Tests  for  Milk. — The  amount  of  cream  is  estimated  by  placing  the  milk  for 
24  hours  in  a  tall  cylindrical  glass  graduated  into  a  hundred  parts;  the  cream 
collects  on  the  surface,  and  ought  to  form  from  10-24  vols,  per  cent.  The 
specific  gravity  (fresh  cow's  milk,  1,029-1,034;  when  creamed,  1,032-1,040)  is 
estimated  with  an  araeometer  or  lactometer  at  15°C.  The  sugar  is  estimated  by 
titration  with  Fehling's  solution  (p.  298),  but  in  this  case  1  cubic  centimetre  of 
this  solution  corresponds  to  0'0067  grm.  of  milk-sugar;  or  its  amount  may  be 
estimated  with  the  j^olariscopic  apparatus  [vol.  ii).  The  proteids  are  precipitated 
and  the  fats  extracted  with  ether.  The  fats  in  fresh  milk  form  about  3  per  cent., 
and  in  skimmed  milk  1^  per  cent.  The  amount  of  water  in  relation  to  the  milk- 
globules  is  estimated  by  the  lactoscope  (the  diaphanometer  of  Donn^,  modified  by 
Vogel  and  Hoppe-Seyler),  which  consists  of  a  glass-vessel  with  plane  parallel  sides 
placed  1  centimetre  apart.  A  measured  quantity  of  milk  is  taken,  and  water  is 
added  to  it  from  a  burette  until  the  outline  of  a  candle  flame  placed  at  a  distance 
of  1  metre  can  be  distinctly  seen  through  the  diluted  milk.  This  is  done  in  a  dark 
room.  For  1  cubic  centimetre  of  good  cow's  milk,  70-85  centimetres  water  are 
required. 

Various  substances  pass  into  the  milk  ivhen  they  are  administered  to  the  mother — 
many  odoriferous  vegetable  bodies,  e.g.,  anise,  vermuth  garlic,  &c. ;  opium,  indigo, 
salicylic  acid,  iodine,  iron,  zinc,  mercury,  lead,  bismuth,  antimony.  In  osteo- 
malacia the  amount  of  lime  in  the  milk  is  increased  (Gusserow).     Potassium  iodide 


468  EGGS. 

diminishes  the  secretion  of  milk  by  affecting  the  secretory  function  (Stumpf). 
Amongst  abnormal  constituents  are— haemoglobin,  bile-pigments,  mucin, 
blood-corpuscles,  pus,  fibrin.  Numerous  fungi  and  other  low  organisms  develop 
in  evacuated  milk,  and  the  rare  blue  milk  is  due  to  the  development  of  Bacterium 
cyanogeneum  (Fuchs,  Neelsen).  The  blue  colour  is  due  to  aniline  blue  derived 
from  casein  (Erdmann).  The  milk-serum  is  blue,  not  the  fungus.  Blue  milk  is 
unhealthy,  and  causes  diarrhoea  (Hosier).  Red  and  yellow  milk  are  produced  by 
a  similar  action  of  chromogenic  fungi  (p.  373).  The  former  is  produced  by 
Micrococcus  prodigiosus,  which  is  colourless.  The  colour  seems  to  be  due  to 
fuchsin.  The  yellow  colour  is  produced  by  Bacterium  synxanthum  (Ehrenberg), 
and  the  colour  is  also  due  to  s^n  aniline  substance  (Schroter). 

Preparations  of  Milk. — (!•)  Condensed  vnilk — 80  grms.  cane-sugar  are  added 
to  1  litre  of  milk;  the  whole  is  evaporated  to  |^;  and  while  hot  sealed  up  in  tin 
cans  (Lignac).  For  children  one  teaspoonful  is  dissolved  in  a  pint  of  cold  water, 
and  then  boiled. 

(2. )  Koumiss  is  prepared  by  the  Tartars  from  mare's  milk.  Koumiss  and  sour 
milk  are  added  to  milk,  the  whole  is  violently  stirred,  and  it  undergoes  the 
alcoholic  fermentation,  whereby  the  milk-sugar  is  first  changed  into  galactose, 
and  then  into  alcohol;  so  that  koumiss  contains  2-3  per  cent,  of  alcohol;  while  the 
casein  is  at  first  precipitated,  but  is  afterwards  partly  redissolved  and  changed 
into  acid-albumin  and  peptone  (Dochmann). 

(3.)  Cheese  is  prepared  by  coagulating  milk  with  rennet,  allowing  the  whey 
to  separate,  and  adding  salt  to  the  curd.  When  kept  for  a  long  time  cheese 
"ripens,"  the  casein  again  becomes  soluble  in  water,  probably  from  the  formation 
of  soda  albuminate;  in  many  cases  it  becomes  semi-fluid  when  it  takes  the 
characters  of  peptones.  When  further  decomposition  occurs,  leucin  and  tyrosin 
are  formed.  The  fats  increase  at  the  expense  of  the  casein,  and  they  again  undergo 
further  change,  the  volatile  fatty  acids  giving  the  characteristic  odour.  The 
formation  of  peptone,  leucin,  tyrosin,  and  the  decomposition  of  fat  recalls  the 
digestive  processes, 

232.  Eggs. 

Eggs  must  also  be  regarded  as  a  complete  food,  as  the  organism 
of  the  young  chick  is  developed  from  them.  The  yelk  contains  a 
characteristic  proteid  body,  Vitellin  (§  249),  and  an  albuminate  in  the 
envelopes  of  the  yeUow  yelk  spheres — NucUin,  from  the  v^'hite  yelk ; 
fats  in  the  yellow  yelk  (palmitin,  olein),  cholesterin,  much  lecithin; 
and  as  its  decomposition  product,  glycerin-phosphoric  acid — grajpe- 
sugar,  pigments  (lutein),  and  a  body  containing  iron  and  related  to 
haemoglobin  j  lastly,  salts  qualitatively  the  same  as  in  blood— quanti- 
tatively as  in  the  blood-corpuscles — gases. 

The  chief  constituent  of  the  white  of  egg  is  egg-albumin  (§  249), 
together  with  a  small  amount  of  palmitin  and  olein  partly 
saponified  with  soda;  grape-sugar,  extractives;  lastly  salts,  quali- 
tatively resembling  those  of  blood,  but  quantitatively  like  those  of 
serum,  and  a  trace  of  fluorine. 

Kelatively  more  of  the  nitrogenous  constituents  than  the  fatty 
constituents  of  eggs  are  absorbed  (Rubner). 


FLESH  AND  ITS  PREPARATIONS. 


469 


233.  Flesh  and  its  Preparations. 

Flesh,  in  the  form  in  which  it  is  eaten,  contains  in  addition  to 
the  muscle-substance  proper,  more  or  less  of  the  elements  of  fat, 
connective-  and  elastic-tissue  mixed  with  it.  The  following  results 
refer  to  flesh  freed  as  much  as  possible  from  these  constituents. 
The  chief  proteid  constituent  of  the  contractile  muscular  substance 
is  myosin  (Kiihne);  serum-albumin  occurs  in  the  fluid  of  the  fibres, 
in  the  lymph  and  blood  of  muscle.  The  fats  are  for  the  most  part 
derived  from  the  interfibrillar  fat  cells,  and  so  are  lecithin  and 
cholesterin  from  the  nerves  of  the  muscles;  the  gelatin  is  derived 
from  the  connective-tissue  of  the  perimysium,  perineurium,  and  the 
walls  of  blood-vessels  and  tendons.  The  red  colour  of  the  flesh  is 
due  to  the  hsemoglobin  present  in  the  sarcous  substance  (Kiihne, 
Gscheidlen).  Elastin  occurs  in  the  sarcolemma,  neurilemma,  and 
in  the  elastic  fibres  of  the  perimysium  and  walls  of  the  vessels; 
the  small  amount  of  keratin  is  derived  from  the  endothelium  of  the 
vessels.  The  chief  muscular  substance,  the  result  of  the  retrogressive 
metabolism  of  the  sarcous  substance,  is  kreatin  (Chevreul — 0*25  per 
cent..  Perls) ;  Jcreatinin,  the  inconstant  inosinic  acid,  then  lactic,  or  rather 
sarcolactic  acid  (see  Muscle).  Farther,  taurin,  sarJcin,  xanthin,  uric  acid,  car- 
nin,  inosit  (most  abundant  in  the  muscles  of  drunkards),  dextrin  (in  horse 
and  rabbit,  not  constant — Sanson,  Limpricht) ;  grape-sugar  (Meissner), 
but  it  is  very  probably  derived  post  mortem  from  glycogen  (0*43  per 
cent.),  which  occurs  in  considerable  amount  in  foetal  muscles  (0. 
Nasse) ;  lastly,  fatty  acids.  Amongst  the  salts,  potash  and  phosphoric 
acid  compounds  (Braconnot)  are  most  abundant ;  magnesium  phosphate 
exceeds  calcium  phosphate  in  amount. 

In  100  parts  FLESH  there  is,  according  to  Schlossberger  and  v.  Bibra — 


Ox. 

Calf. 

Deer. 

Pig. 

Man. 

Fowl. 

Carp. 

Frog. 

Water,       . 

77-50 

78-20 

74-63 

78-30 

74-45 

77-30 

79-78 

80-43 

Solids, 

22-50 

21-80 

25-37 

21-70 

25-65 

22-7 

20-22 

19-57 

Soluble  Albvimin, 
Colouring  Matter, 

J2-20 

2-60 

1-94 

2-40 

1-93 

3-0 1 

2-35 

1-86 

Glutin,       . 

1-30 

1-60 

0-50 

0-80 

2-07 

1-2 

1-98 

2-48 

Alcoholic  Extract,     . 

1-50 

1-40 

4-75 

1-70 

3-71 

1-4 

3-47 

3-46 

Fats, 

! 

1-30 

... 

2-30 

1-11 

010 

Insoluble      Albumin, 

Blood-vessels,  &c., 

17-50 

16-2 

16-81 

16-81 

15-54 

16-5 

fll-31 

11-67 

470  COMPOSITION   OF  FLESH, 

lu  100  parts  ASH  there  is— 


Horse. 

Ox. 

Calf. 

Pig. 

Potash, 

39*40 

35'94 

34-40 

3779 

Soda, 

4-86 

2  35 

4-02 

Magnesia,    . 

3-88 

3-31 

1-45 

4-81 

Chalk, 

1-80 

1-73 

1-99 

7-54 

Potassium, 

5-36 

... 

... 

Sodium, 
Chlorine,    . 

1  -} 

4-86 

-f  10-59  1 

0-40 
0-62 

Iron  oxide. 

1-0 

0-98 

0-27 

0-35 

Phosphoric  Acid, 

4674 

34'36 

4813 

44-47 

Sulphuric           ,, 

0-30 

3-37 

Silicic                 ,, 

... 

2-07 

0-81 

Carbonic            ,, 

8-02 

... 

... 

Ammonia, 

... 

015 

... 

The  amount  of  fat  in  flesh  varies  very  much  according  to  the  condition  of  the 
animal.  After  removal  of  the  visible  fat,  human  flesh  contains  7*15,  ox  11 '12, 
calf  10-4,  sheep  3-9,  wild  goose  8*8,  fowl  2-5  per  cent. 

The  amount  of  extractives  is  most  abundant  in  those  animals  which  exhibit 
energetic  muscular  action;  hence  it  is  largest  in  wild  animals.  The  extract  is 
increased  after  vigorous  muscular  action,  when  sarcolactic  acid  is  developed,  and 
the  flesh  becomes  more  tender  and  is  more  palatable.  Some  of  the  extractives 
excite  the  nervous  system,  e.g.,  kreatin  and  kreatinin ;  and  others  give  to  flesh  its 
characteristic  agreeable  taste  ("  osmasome  "),  but  this  is  also  partly  due  to  the 
difierent  fats  of  the  flesh,  and  is  best  developed  when  the  flesh  is  cooked.  The 
extractives  in  100  parts  of  flesh— in  man  and  pigeon,  3 ;  deer  and  duck,  4 ;  swallow, 
7  per  cent. 

Preparation,  or  Cooking  of  Flesh.— As  a  general  rule,  the  flesh  of  young 
animals,  owing  to  the  sarcolemma,  connective-tissue,  and  elastic  constituents 
being  less  tough,  is  more  tender  and  more  easily  digested  than  the  flesh  of  old 
animals;  after  flesh  has  been  kept  for  a  time  it  is  more  friable  and  tender,  as  the 
inosit  becomes  changed  into  sarcolactic  acid  and  the  glycogen  into  sugar,  and 
this  again  into  lactic  acid,  whereby  the  elements  of  the  flesh  undergo  a  kind  of 
maceration.  Finely-divided  flesh  is  more  digestible  than  when  it  is  eaten  in  large 
pieces.  In  cooking  meat,  the  heat  ought  not  to  be  too  intense,  and  ought  not  to 
be  continued  too  long,  as  the  muscular  fibres  thereby  become  hard  and  shrink  very 
much.  Those  parts  are  most  digestible  which  are  obtained  from  the  centre  of  a 
roast  where  they  have  been  heated  to  60-70''C.,  as  this  temperature  is  sufficient, 
with  the  aid  of  the  acids  of  the  flesh,  to  change  the  connective-tissue  into  gelatin, 
whereby  the  fibres  are  loosened,  so  that  the  gastric  juice  readily  attacks  them. 
In  roasting  beef,  apply  heat  suddenly  at  first,  to  coagulate  a  layer  on  the  surface, 
which  prevents  the  exit  of  the  juice. 

Meat  Soup  is  best  prepared  by  cutting  the  flesh  into  pieces  and  placing  them 
for  several  hours  in  cold  water,  and  afterwards  boiling.  Liebig  found  that  6 
parts  per  100  of  ox  flesh  were  dissolved  by  cold  water.  When  this  cold  extract 
was  boiled,  2  '95  parts  were  precipitated  as  coagulated  albumin,  which  is  chiefly 
removed  by  "skimming,"  so  that  only  3-05  parts  remain  in  solution.  From  100 
parts  of  flesh  of  fowl,  8  parts  were  extracted,  and  of  these  4*7  coagulated  and  3*3 


VEGETABLE   FOODS. 


471 


remained  dissolved  in  the  soup.  By  boiling  for  a  very  long  time,  part  of  the 
albumin  may  be  redissolved  (Mulder).  The  dissolved  substances  are : — 
1.  Inorganic  salts  of  the  meat,  of  which  82  "27  per  cent,  pass  into  the  soup  ;  the 
earthy  phosphates  chiefly  remain  in  the  cooked  meat.  2.  Kreatin,  kreatinin,  the 
inosinates  and  lactates  which  give  to  broth  or  beef-tea  their  stimulating  qualities, 
and  a  small  amount  of  aromatic  extractives.  3.  Gelatin,  more  abundantly 
extracted  fi-om  the  flesh  of  young  animals.  According  to  these  facts,  therefore, 
flesh-broth  or  beef-tea  is  a  powerful  stimulant,  supplying  muscle  with  restoratives, 
but  is  not  a  food  in  the  ordinarj'  sense  of  the  term.  The  flesh  after  the  extraction 
of  the  broth  is  still  available  as  a  food. 

Liebig's  Extract  of  Meat  is  an  extract  of  flesh  evaporated  to  a  thick  syrupy 
consistence.  It  contains  no  fat  or  gelatin,  and  is  chiefly  a  solution  of  the 
extractives  and  salts  of  flesh. 

[Mastermami  has  shown  that  the  chemical  analysis  of  beef -tea  is  analogous  to 
that  of  urine,  except  that  it  contains  less  urea  and  uric  acid.  ] 


234.  Vegetable  Foods. 


The  nitrogenous  constituents  of  plants  are  not  so  easily  absorbed  as 
animal  food  (Rubner).  Carbohydrates,  starch,  and  sugar  are  very 
completely  absorbed,  and 
even  a  not  inconsiderable 
proportion  of  cellulose 
may  be  digested  (Weiske, 
Konig).  The  more  fats 
that  are  contained  in  the 
vegetable  food,  the  less 
carbohydrates 
and      absorbed 


are      the 

digested 

(Rubner). 

1.  The  cereals  are  most 
important  vegetable  foods; 
they  contain  proteids, 
starch,  salts,  and  water  to 
14  per  cent.  The  nitro- 
genous glutin  is  most  abun- 
dant under  the  husk 
(Payen).   The  use  of  whole 

meal  containing  the  outer  layers  of  the  grain  is  highly  nutritive,  but 
bread  containing  much  bran  is  somewhat  indigestible  (Rubner). 
[A  section  of  a  wheat  grain  with  its  layers  of  glutin  is  shown  in 
Fig.  173.]     Their  composition  is  the  following: — 


Fig.  173. 

Microscopic  characters  of  wheat—  x  200  ;  a,  cells 
of  the  bran  ;  b,  cells  of  thin  cuticle ;  c,  glutin 
cells ;  d,  starch  cells ;  B,  wheat  starch  x  350. 


472 


fULSES,  POTATOES,  FRUITS. 


100  PARTS  OF  THE  DRY  MEAL  CONTAIN 


100  PARTS  OF  ASH  CONTAIN 


Wheat, 
Rye,  . 
Barley, 
Maize,. 
Rice,  . 
Buckwheat, 


16-52  p.c. 
11-92 
17-70 
13-65 
7-40 
6-8-10-5 


RED 
■WHEAT. 


56-25  p.c. 

60-91 

38-31 

77-74 
86-21 
65-05 


27*87 
15-75 
1-93 
9-60 
1-36 
49-36 
0-15 


Potash,  . 

Soda,  .  . 
Lime,  .  . 
Magnesia, 
Iron  oxide, 

Phosphoric  Acid, 

Silica, 

(Will,  Fresenius). 


WHITE 
WHEAT. 


33*84 

3-09 

13-54 

0-31 

49-21 


It  is  curious  to  observe  that  soda  is  absent  from  white  wheat,  its  place  being 
taken  by  other  alkalies.  Rye  contains  more  cellulose  and  dextrin  than  wheat,  but 
less  sugar;  rye  bread  is  usually  less  porous. 

In  the  preparation  of  bread,  the  meal  is  kneaded  with  water  until  dough  is 
formed,  and  to  it  is  added  salt  and  yeast  (saccharomycetes  cerevisiae).  When 
placed  in  a  warm  oven,  the  proteids  of  the  meal  begin  to  decompose  and  act  as  a 
ferment  upon  the  swollen  up  starch,  which  becomes  in  part  changed  into  sugar. 
The  sugar  is  farther  decomposed  into  CO2  and  alcohol,  the  CO2  forms  bubbles, 
which  make  the  bread  spongy  and  porous.  The  alcohol  is  driven  off  by  the  baking 
(200°),  while  much  soluble  dextrin  is  formed  in  the  crust  of  the  bread. 

2.  The  Pulses  contain  much  albumin,  especially  vegetable  casein  or  legumin; 
together  with  starch,  lecithin,  cholesterin,  and  9-19  per  cent,  water. 
Peas  contain  28-02  proteids,  and  38-81  starch:  beans  28-54,  and 
37-50 :  lentils,  29-31,  and  40,  and  more  cellulose.  Owing  to  the 
absence  of  glutin  they  do  not  form  dough,  and  bread  cannot  be 
prepared  from  them.  On  account  of  the  large  amount  of  proteids 
which  they  contain  they  are  admirably  adapted  as  food  for  the 
poorer  classes. 

3.  Potatoes  contain  70-81  per  cent,  water.  In  the  fresh  juicy  cellular 
tissue,  which  has  an  acid  reaction,  from  the  presence  of  phosphoric, 
malic,  and  hydrochloric  acids,  there  is  16-23  per  cent,  of  starch,  2-5 
soluble  albumin,  globulin  (ZoUer),  and  a  trace  of  asparagin.  The 
envelopes  of  the  cells  swell  up  by  boiling,  and  are  changed  into  sugar 
and  gums  by  dilute  acids.  The  poisonous  solanin  occurs  in  the 
sprouts.  In  100  parts  of  potato  ash,  May  found  46-96  potash,  2-41 
sodium  chloride,  8-11  potassium  chloride,  6-50  sulphuric  acid  derived 
from  burned  proteids,  7-17  silica. 

4.  In  Fruits  the  chief  nutrient  ingredients  are  sugar  and  salts ;  the 
organic  acids  give  them  their  characteristic  taste,  the  gelatinising 
substance  is  the  soluble  so-called  pectin  (CggH^gOgg),  which  can  be  pre- 
pared artificially  by  boiling  the  very  insoluble  pectose  of  unripe  fruits 
and  mulberries. 


CONDIMENTS,  TEA,  COtTEE.  473 

5.  The  Green  VegetaWes  are  specially  rich  in  salts,  which  resemble  the 
salts  of  the  blood;  thus,  dry  salad  contains  23  per  cent,  of  salts, 
which  closely  resemble  the  salts  of  the  blood.  Of  much  less  importance 
are  the  starch,  cell-substance,  dextrin,  sugar  and  the  small  amount  of 
albumin  which  they  contain. 


235.  Condiments— Coffee— Tea—Chocolate— 
Alcoholic  Drinks. 

Some  siibstances  are  used  along  witli  food,  not  so  mucli  on  account  of  their* 
nutritive  properties  as  on  account  of  theix*  stimulating  effects  and  agreeable 
qualities,  which  are  exerted  partly  upon  the  organ  of  taste,  and  partly  upon  the 
nervous  system.     These  are  called  condiments. 

Coffee,  tea,  and  chocolate  are  prepared  as  infusions  of  these  substances.  Their 
chief  active  ingredients  are  respectively  caffein,  thein  (C8H10N4O2  +  H2O),  and 
tlieohromin  (C7H8N'402),  which  are  regarded  as  alkaloids  of  the  vegetable 
bases,  and  which  have  recently  been  prepared  artificially  from  xanthin  (E.  Fischer). 

These  "alkaloids"  occur  as  such  in  the  plants  containing  them;  they  behave 
like  ammonia ;  they  have  an  alkaline  reaction,  and  form  crystalline  salts  with 
acids.  All  these  vegetable  bases  act  upon  the  nervous  system  ;  some  more  feebly 
(as  the  above),  others  more  powerfully  (quinine);  some  stimulate  powerfully,  or 
completely  paralyse  (morphia,  atropin,  strychnin,  curarin,  nicotin,  muscarin). 

All  these  substances  act  on  the  nervous  system;  they  quicken 
thought,  accelerate  movement,  and  stir  one  to  greater  acti\"ity.  In 
these  respects  they  resemble  the  stimulating  extractives — kreatin  and 
kreatinin — of  beef-tea.  Coffee  contains  about  ^  per  cent  of  caffein, 
part  of  which  is  only  liberated  by  the  act  of  roasting.  Tea  has  6  per 
cent,  of  thein,  whilst  green  tea  contains  1  per  cent,  ethereal  oil,  and 
black  tea  \  per  cent.;  in  green  tea  there  is  18  per  cent.,  in  black  15 
per  cent,  tannin;  green  tea  yields  about  46  per  cent.,  and  the  black 
scarcely  30  per  cent,  of  extract. 

The  inorganic  salts  present  are  also  of  importance;  tea  contains  3 "03 
per  cent,  of  salts,  and  amongst  these  are  soluble  compounds  of  iron, 
manganese,  and  soda  salts.  In  coffee,  which  yields  3  "41  per  cent,  of 
ash,  potash  salts  are  most  abundant;  in  all  three  substances  the  other 
salts  which  occur  in  the  blood  are  also  present. 

Alcoholic  Drinks  owe  their  action  chiefly  to  the  alcohol  which  they 
contain.  The  alcohol,  Avhen  taken  into  the  body,  undergoes  certain 
changes  and  produces  certain  effects : — 1.  It  is  oxidised  chiefly  into 
CO2  and  HgO,  so  that  it  is  so  far  a  source  of  heat.  As  it  undergoes 
this  change  very  readily,  when  taken  to  a  certain  extent  it  may  act  as 
a  substitute  for  the  consumption  of  the  tissues  of  the  body,  especially 
when  the  amount  of  food  is  insufficient.     Small  doses  diminish  the 


474  ACTION   OF  ALCOHOL. 

decomposition  of  the  proteids  to  the  extent  of  6-7  per  cent.  Only 
a  very  small  part  of  the  alcohol  is  excreted  in  the  urine ;  the  odour 
of  the  breath  is  not  due  to  alcohol,  but  to  other  volatile  substances 
mixed  with  it,  e.g.,  fusel  oil,  &c.  2.  In  small  doses  it  excites,  while 
in  large  doses  it  paralyses,  the  nervous  system.  By  its  stimulating 
qualities  it  excites  to  greater  action,  which,  however,  is  followed  by 
depression.  3.  It  diminishes  the  sensation  of  hunger.  4.  It  excites 
the  vascular  system,  accelerates  the  circulation,  so  that  the  muscles 
and  nerves  are  more  active  owing  to  the  greater  supply  of  blood.  It 
also  gives  rise  to  a  subjective  feeling  of  warmth.  In  large  doses, 
however,  it  paralyses  the  vessels,  so  that  they  dilate,  and  thus  much  heat 
is  given  off  (§  213^  7,  §  227).  The  action  of  the  heart  also  becomes 
affected,  the  pulse  becomes  smaller,  feebler,  and  more  rapid.  In  high 
altitudes,  the  action  of  alcohol  is  greatly  diminished,  owing  to  the 
diminished  atmospheric  pressure  whereby  it  is  rapidly  given  off  from 
the  blood. 

Alcohol  in  small  doses  is  of  great  use  in  conditions  of  temporary 
want,  and  where  the  food  taken  is  insufficient  in  quantity.  When 
alcohol  is  taken  regularly,  more  especially  in  large  doses,  it  affects  the 
nervous  system,  and  undermines  the  psychical  and  corporeal  faculties, 
partly  from  the  action  of  the  impurities  which  it  may  contain,  such 
as  fusel  oil,  which  has  a  poisonous  effect  upon  the  nervous  system, 
partly  by  the  direct  effects,  such  as  catarrh  and  inflammation  of  the 
digestive  organs,  which  it  produces,  and  lastly,  by  its  effect  upon  the 
normal  metabolism. 

Preparation. — Alcoholic  drinks  are  prepared  by  the  fermentation  of  various 
carbohydrates,  such  as  sugar  derived  from  starch.  The  alcoholic  fermentation,  such 
as  occurs  in  the  manufacture  of  beer,  is  caiised  by  the  development  of  the  yeast 
plant,  Saccharomycetes  cerevisias  ;  while  in  the  fermentation  of  the  grape  (wine), 
iS.  ellipsoideus  is  the  species  present.  The  yeast  takes  the  substances  necessary 
for  the  maintenance  of  its  organic  processes  directly  from  the  mixture  of  the 
sugar — A'iz.,  carbohydrates,  proteids,  and  salts,  especially  calcium  and  potassium 
phosphates  and  magnesium   sulphate.     These  substances  undergo  decomposition 


2. 


1,  Isolated  yeast   cells;   2,  3,  yeast  cells  budding;  4,  5,  so-called   endogenous 
formation  of  cells ;  6,  sprouting  and  formation  of  buds. 

■within  the  cells  of  the  yeast  plant,  which  multiply  during  the  process,  and  there 
are  produced  alcohol  and  COj  (p.  298),  together  with  glycerine  (3 •2-3-6  per  cent.) 


PREPARATION   OF  ALCOHOLIC  DRINKS.  475 

and  succinic  acid  (0"6-0*7  per  cent.).  Yeast  is  either  added  intentionally  or  it 
reaches  the  mixture  from  the  air,  which  always  contains  its  spores.  When  yeast 
is  completely  excluded,  or  if  it  be  killed  by  boiling,  [or  if  its  action  be  prevented 
by  the  presence  of  some  germicide],  the  fermentation  does  not  occur.  The 
alcoholic  fermentation  is  due  to  the  vital  activity  of  a  low  organism  (Schwann, 
Mitscherlich,  Pasteur). 

In  the  preparation  of  brandy,  the  starch  of  the  grain  or  potatoes  is  first 
changed  into  sugar  by  the  action  of , diastase  or  maltin.  Yeast  is  added,  and  fer- 
mentation thereby  produced ;  the  mixture  is  distilled  at  78'3°C.  The  fusel  oil  is 
prevented  from  mixing  with  the  alcohol  by  passing  the  vapour  through  heated 
charcoal.     The  distillate  contains  50-55  per  cent,  of  alcohol. 

In  the  preparation  of  wine,  the  saccharine  juice  of  the  grape — the  must — after 
being  expressed  from  the  grapes  is  exposed  to  the  air  at  10-15°C.,  and  the  yeast 
cells,  which  are  floating  about,  drop  into  it  and  excite  fermentation,  which  lasts 
10-14  days,  when  the  yeast  sinks  to  the  bottom.  The  clear  wine  is  drawn  off 
into  casks,  where  it  becomes  turbid  by  undergoing  an  after -fermentation,  until  the 
sugar  is  converted  into  alcohol  and  COo,  which  is  accompanied  by  the  deposition 
of  some  yeast  and  tartar.  If  all  the  sugar  is  not  decomposed — which  occurs  when 
there  is  not  sufficient  nitrogenous  matter  present  to  nourish  the  yeast — a  sweet 
tcine  is  obtained.  "Wine  contains  89-90  per  cent,  water,  7-8  per  cent,  alcohol, 
together  with  sethylic,  propylic,  and  butylic  alcohol.  The  red  colour  of  some 
wines  is  due  to  the  colouring  matter  of  the  skin  of  the  grapes,  but  if  the  skins  be 
removed  before  fermentation,  red  grapes  yield  white  wine. 

When  wine  is  stored  it  develops  a  fine  flavour  or  bouquet.  The  characteristic 
vinous  odour  is  due  to  cenanthic  ether.  The  salts  of  wine  closely  resemble  the  salts 
of  the  blood. 

In  the  preparation  of  beer  the  grain  is  moisten,  and  allowed  to  germinate 
when  the  temperature  rises,  and  the  starch  (68  per  cent,  in  barley)  is  changed 
into  sugar.  Thus  ^'maW  is  formed,  which  is  dried,  and  afterwards  pulverised, 
and  extracted  with  water  at  70-75",  the  watery  extract  being  the  "wort." 
Hops  are  added  to  the  wort,  and  the  whole  is  evaporated,  when  the  proteids  are 
coagulated.  Hops  give  beer  its  bitter  taste,  make  it  keep,  while  their  tannic  acid 
precipitates  any  starch  that  may  be  present,  and  clarifies  the  wort.  After  being 
boiled,  it  is  cooled  rapidly  (12°C.);  yeast  is  added,  and  fermentation  goes  on 
rapidly  and  with  considerable  effervescence  at  lO^-M".  Beer  contains  75-95  per 
cent,  water;  alcohol,  2-5  per  cent,  (porter  and  ale,  to  S  per  cent.);  CO2,  0'l-0'8 
per  cent.;  sugar,  2-8  per  cent.;  gum,  dextrin,  2-10  per  cent.;  the  hops  yield 
traces  of  protein,  fat,  lactic  acid,  ammonia  compounds,  the  salts  of  the  grain  and 
of  the  hops. 

In  the  ash,  there  is  a  great  preponderance  of  phosphoric  acid  and  potash,  both 
of  which  are  of  great  importance  for  the  formation  of  blood.  In  100  parts  of  ash 
there  are  40 '8  potash,  20 '0  phosphorus,  magnesium  phosphate  20,  calcium 
phosphate  2'6,  salica  16"6  per  cent.  The  formation  of  blood,  muscle,  and  other 
tissues  from  the  consumption  of  beer  is  due  to  the  phosphoric  acid  and  potash, 
while  if  too  much  be  taken,  the  potash  produces  fatigue. 

Condiments  are  taken  with  food,  partly  on  account  of  their  taste,  and 
partly  because  they  excite  secretion.  Common  salt,  in  a  certain  sense, 
is  a  condiment.  We  may  also  include  many  substances  of  unknown 
constitution  which  act  upon  the  gustatory  organs,  e.g.,  substances  in 
the  crust  of  bread  and  in  meat  which  has  been  roasted. 


Phenomena  and  laws  of  letalDolism. 


236.  Equilibrium  of  the  Metabolism. 

By  this  term  is  meant  that,  under  normal  physiological  conditions, 
just  as  much  material  is  absorbed  and  assimilated  from  the  food,  as  is 
removed  from  the  body  by  the  excretory  organs  in  the  form  of  effete 
or  end-products,  the  result  of  the  retrogressive  tissue  changes.  The 
income  must  always  balance  the  expenditure;  wherever  a  tissue  is 
used  up,  it  must  be  replaced  by  the  formation  of  new  tissue.  As  long 
as  the  body  continues  to  grow,  the  increase  of  the  body  corresponds  to 
a  certain  increase  of  formation,  whereby  the  metabolism  of  the 
growing  parts  of  the  body  is  2 "5  to  6 "3  times  greater  than  that  of  the 
parts  already  formed  (Crusius).  Conversely,  during  senile  decay,  there 
is  an  excess  of  expenditure  from  the  body. 

Methods. — The  normal  equilibrium  of  the  metabolism  of  the  body  is  investi- 
gated—(1)  By  determining  chemically  that  the  sum  of  all  the  substances  passing 
into  the  body  is  equal  to  the  sum  of  all  the  siibstances  given  off  from  it.  Thus 
the  C,  N,  H,  0,  salts  and  water  of  the  food,  and  the  0  inspired,  must  be  equal  to 
the  C,  H,  N,  0,  salts  and  water  given  off  in  the  excreta  (urine,  faeces,  air  expired, 
water  excreted).  (2)  The  physiological  equilibrium  is  determined  empirically  by 
observing  that  the  body  retains  its  normal  weight  with  a  given  diet;  so  that  by 
simply  weighing  a  person,  a  physician  is  enabled  to  determine  exactly  the  state  of 
convalescence  of  his  patient. 

The  tedious  process  of  making  an  elementary  analysis  of  the  metabolic  substances 
was  first  undertaken  in  the  Munich  School  by  v.  Bischoff,  v.Voit,  v,  Pettenkofer,  and 
others.  Their  observations  showed,  that  in  the  circulation  of  materials  the  C  and 
N  were  the  most  important.  The  total  amount  of  C  taken  in  the  food,  if  the 
metabolism  be  in  a  condition  of  physiological  equilibrium,  must  be  equalled  by  the 
C  in  the  CO2  given  off  by  the  lungs  and  skin  (90  per  cent.),  together  with  the 
relatively  small  amount  of  C  in  the  organic  excreta  of  the  urine  and  f^ces  (10  per 
cent.).  With  regard  to  the  N,  nearly  all  the  N  taken  in  with  the  food  is  excreted 
within  24  hours  in  the  form  of  urea.  A  very  small  amount  of  nitrogenous  matter 
is  excreted  in  the  fseces,  while  the  other  nitrogenous  urinary  constituents  (uric 
acid,  kreatin,  &c.)  represent  about  2  per  cent,  of  N.  A  trace  of  the  N  is  given  off 
by  the  breath  (p.  255),  and  a  minute  proportion  in  combination,  in  the  epidermal 
scales  (50  milligrammes  daily  in  the  hair  and  nails)  and  in  the  sweat. 

That  nearly  all  the  N  taken  in  the  food  reappears  in  the  urrine  and 
fseces,  as  v.  Voit  showed  for  carnivora,  and  Henneberg,  Stohman  and 
Grouven  for  herbivora,  and  v.  Kanke  for  man,  is  contradicted  partly  by 
old  and  partly  by  new  observations  (Barral,  Boussingault,  Bischoff, 
Regnault  and  Reiset,  Seegen  and  Nowak),  which  go  to  show  that  the 


EQUILIBRIUM  OF  THE  METABOLISM.  477 

whole  of  the  N  cannot  be  recovered  from  these  excretions,  but  on  the 
contrary  there  is  a  considerable  deficit. 

According  to  Seegen  and  Nowak,  1  kilo,  weight  of  a  living  animal  excretes  of 
gaseous  N  per  hour,  thus — rabbit,  4-5  milligrammes  (according  to  Leo,  only  -^^  of 
this  value) ;  dog,  8  milligrammes  ;  fowls,  pigeons,  7-9  milligrammes.  According 
to  Leo,  only  0'55  per  cent,  of  the  albumin  transfonned  within  the  body  (assuming 
15  per  cent.  N  in  albumin)  is  given  off  in  the  form  of  gaseous  N. 

The  H  leaves  the  body  chiefly  in  the  form  of  water — a  part,  however,  is  in 
combination  in  other  excreta;  the  0  is  chiefly  excreted  as  CO2  and  water;  a  little 
is  given  off  in  combination  in  other  excreta;  water  is  given  off  by  evaporation  from 
the  lungs  and  skin.  As  H  is  oxidised  to  form  HoO,  more  water  is  excreted  than 
is  taken  in.  With  regard  to  the  salts,  most  of  the  readily  soluble  salts  are  given 
off  by  the  urine;  less,  especially  potash  salts  and  rather  insoluble  salts,  in  the 
faeces,  while  others,  e.g.,  common  salt,  are  given  off  in  the  sweat.  Of  the  sulphur 
of  albumin,  about  one-half  is  excreted  in  the  sulphur  compounds  in  the  urine, 
and  the  other  half  in  the  fasces  (taurin)  and  in  the  epidermal  tissues. 

Every  body  has  a  minimum  and  a  maximum  limit  with  reference  to 
its  metabolism,  according  to  the  amount  of  work  done  by  the  body, 
and  its  weight.  If  less  food  be  given  than  is  necessary  to  maintain  the 
former,  the  body  loses  weight;  while,  if  more  be  given  after  the 
maximum  limit  is  reached,  the  food  so  given  is  not  absorbed,  but 
remains  as  a  floating  balance  and  is  given  off  with  the  faeces.  When 
food  is  liberally  supplied  and  the  weight  increases,  of  course  the 
minimum  limit  rises;  hence,  during  the  process  of  "feeding  '  or 
"  fattening,"  the  income  necessary  is  very  much  greater  than  in  poorly- 
fed  animals,  for  the  same  increase  of  the  body-weight.  By  continuing 
the  process,  a  condition  is  at  last  reached,  in  which  the  digestive 
organs  are  just  sufficient  to  maintain  the  existing  condition,  but  cannot 
act  so  as  to  admit  of  new  additions  being  made  to  the  body-weight 
(v.  BischofF,  V.  Voit,  v.  Pettenkofer). 

By  the  term  "  luxus  consumption "  is  meant  the  direct  combustion 
or  oxidation  of  the  superfluous  food  stuffs  absorbed  into  the  blood. 
This,  however,  does  not  exist ;  on  the  contrary,  the  material  in  the 
juices  is  always  being  used  for  building  up  the  tissues.  The  albumin 
found  in  the  fluids,  which  everywhere  permeate  the  tissues,  has  been 
called  "  circulating  albumin,"  and,  according  to  v.  Voit,  it  may  undergo 
decomposition  sooner  than  the  organised  "  organ  albumin,'^  which  forms 
an  integral  part  of  the  tissues. 

According  to  v.  Voit  only  1  per  cent,  of  the  organ  albumin  present  in 
the  body,  whUe  70  per  cent,  of  the  circulating  albumin,  is  transformed 
in  24  hours. 

The  excretion  of  N  after  taking  food  is  not  equal  from  hour  to  hour ;  it  rises 
rapidly  at  first,  reaches  a  maximum  in  5-6  hours,  and  then  gradually  falls.  The 
same  is  the  case  with  the  excretion  of  S  and  P,  only  in  these  cases,  after  a  flesh 
diet,  the  maximum  is  reached  at  the  fourth  hour.     After  the  addition  of  fat  to  a 


478  REQUISITES  FOR  A  PERFECT   DIET. 

flesh  diet,  the  excretion  of  N  and  S  is  uniform  from  hour  to  hour  (Feder  and  v. 
Voit). 

Quality  and  Quantity  of  the  Income  in  a  Healthy  Adult. 

As  far  as  his  organisation  is  concerned,  man  belongs  to  the 
omnivorous  animals,  i.e.,  those  that  can  live  upon  a  mixed  diet. 

Requisites. — Man  requires  for  his  existence  and  to  maintain  health 
the  following  four  groups  of  foods  ;  none  of  them  must  be  absent  from 
the  food  for  any  length  of  time.     They  are  : — 

1.  Water— for  an  adult  in  his  food  and  drink,  2,700-2,800  grms. 
daily  (§  229  and  §  247,  1). 

2.  Inorganic  Substances  are  an  integral  part  of  all  tissues,  and  with- 
out them  the  tissues  cannot  be  formed.  They  occur  in  ordinary  food. 
The  addition  of  too  much  salt  increases  the  consumption  of  water,  and 
this  in  turn  increases  the  transformation  of  N  in  the  body  (Weiske). 
If  an  animal  be  deprived  of  salts,  nutrition  is  interfered  with ;  food 
deprived  of  its  lime  affects  the  formation  of  the  bones ;  deprival  of 
common  salt  causes  albuminuria  (247,  A,  III). 

The  alkaline  salts  serve  to  neutralise  the  sulphuric  acid  formed  by 
the  oxidation  of  the  sulphur  of  the  proteids  (E.  Salkowski,  Bunge, 
Lunin). 

Sodium  acetate  in  large  doses  causes  diuresis,  and  diminishes  the  transforma- 
tion of  nitrogenous  substances  in  the  body,  and  the  same  diminution  is  caused  by 
sodium  sulphate  and  phosphate ;  sodium  carbonate  (?  Ott)  increases  the  trans- 
formation of  nitrogenous  substances  (J.  Mayer),  diminishes  the  uric  acid,  and 
increases  the  urea  in  the  urine. 

Only  in  times  of  famine  is  man  driven  to  eat  large  quantities  of  inorganic  sub- 
stances, to  extract  the  organic  matter  mixed  therewith.  A.  v.  Humboldt  states,  in 
regard  to  the  inhabitants  of  the  Orinocco,  that  they  eat  a  kind  of  earth  which  con- 
tains innumerable  infusoria. 

3.  At  least  one  animal  or  vegetable  albuminous  body  or  proteid 
(§  248,  §  250).  The  proteids  are  required  to  replace  the  used-up  nitro- 
genous tissues,  e.g.,  for  muscles.  They  contain  15  "4  to  16*5  per 
cent.  K 

Asparagin,  in  combination  with  gelatin,  can  replace  albumin  in  the  food 
(Weiske),  while  asparagin  alone  limits  the  decomposition  of  albumin  in  herbivora 
(Weiske,  Zuntz,  Bahlmann,  Lehmann),  but  not  in  carnivora  (J.  Munk). 
Ammoniacal  salts,  glycocoU,  sarkosin,  andbenzamid,  increase  the  amount  of  albu- 
min in  the  body. 

4.  At  least  one  fat  (§  251),  or  a  digestible  carbohydrate  (§  252). 
These  chiefly  serve  to  replace  the  transformed  fats  and  non-nitrogenous 
constituents.  Owing  to  the  large  amount  of  C  which  they  contain, 
when  they   undergo   oxidation,  they  form   the   chief  source   of  the 


COMPOSITION   OF  FOODS. 


479 


heat  of  the  body  (§  206).  Fats  and  carbohydrates  may  replace 
each  other  in  the  food,  and  in  inverse  proportion  too,  corresponding 
to  the  amount  of  C  which  each  contains.  According  to  v.  Voit,  for 
this  purpose  175  parts  of  starch  by  weight  are  equal  to  100  parts  of  fat. 

Animal  Foods. 

Explanation  of  the  signs. 


Water. 


Beef. 

Pork. 

Fowl. 

Fish. 

Egg. 
Cow'a  milk,     j 
Human  milk.    j~ 


Proteids.       Albuminoids.  N-free  org.  bodies.     Salts. 


62 


55 


78 


76 


73,5 


8B 


"205 


Bi 


33; 


89 


] 


2-5 
1 

1.3 


1 


IPilil 

1111 


I  0-6 

lo-4 


Wheaten-bread. 

Peas. 

Rice. 

Potatoes. 

White  Turnip. 

Cauliflower. 

Beer. 


Water. 


13      a 


Proteids 


^1,3 


Vegetable  Foods, 

Explanation  of  the  signs. 

Digestible     Non- digestible        Salts. 
N-free  organ  bodies. 


75 


90,5 


90 


90 


Fig.  175. 


KSmm 


!l-4 
2-5 
15 
1 


io. 


J  0-5 


480 


AMOUNT  AND   QUALITY   OF   FOOD   REQUIRED, 


Proportion. — With  regard  to  the  relative  proportions  of  the  various 
kinds  of  food  which  ought  to  be  taken,  experience  has  shown  that 
the  diet  best  suited  for  the  body  must  contain  1  part  of  nitro- 
genous foods  to  3^  or,  at  most,  4^  of  the  non-nitrogenous.  Looking  at 
ordinary  foods  from  this  point  of  view,  we  see  how  far  they 
correspond  to  this  requirement,  and  how  several  substances  may  be 
combined  to  produce  a  satisfactory  diet. 


Nit. 

Non-Nit 

1.  Veal, 

10 

1 

2.  Hare's  flesh, 

10 

2 

3.  Beef, 

10 

...      17 

4.  Lentils, 

10 

...      21 

5.  Beans, 

10 

...       22 

6.  Peas, 

10 

...       23 

7.  Mutton,     . 

10 

...      27 

8.  Pork, 

10 

...      30 

9.  Cow's  milk,    . 

10 

...     30 

Nit. 

10.  Human  milk,         10 

11.  Wheaten-flour,  10 

12.  Oat-meal,      .  10 

13.  Rye-meal,      .  10 

14.  Barley-meal,  10 

15.  White  potatoes,  10 

16.  Blue  „  10 

17.  Rice,      .         .  10 

18.  Buckwheat  meal,  10 


Non-Nit. 

37 

46 

50 

57 

57 

86 
115 
123 
130 


An  examination  of  this  table  shows  that,  in  addition  to  human  milk,  wheat- 
flour  has  the  right  proportion  of  nitrogenous  to  non-nitrogenous  substances.  A 
man  who  tries  to  nourish  himself  on  beef  alone,  commits  as  great  a  mistake  as  one 
who  would  feed  himself  with  potatoes  alone.  Experience  has  taught  people  that 
man  may  live  upon  milk  and  eggs,  but  that  in  addition  to  flesh  we  must  eat 
bread  or  potatoes,  while  pulses  require  fat  or  bacon. 

The  diet  varies  with  the  climate  and  with  the  season  of  the  year.  As  the 
organism  must  produce  more  heat  in  cold  latitudes,  the  inhabitants  of  northern 
climes  must  eat  more  non-nitrogenous  foods,  such  as  fats  and  sugars  or  starches, 
which,  on  account  of  the  large  amount  of  C  they  contain,  are  admirably  adapted 
for  producing  heat  (p.  442). 

The  graphic  representation  of  the  composition  of  Foods  (Fig.  175), 
taken  from  Fick,  shows  at  once  the  relative  proportions  of  the 
food  constituents  and  how  they  vary  from  the  standard  of  1 
nitrogenous  to  3|-4^  non -nitrogenous. 

The  absolute  amount  of  food  stuflfs  required  by  an  adult  in  24 
hours  depends  upon  a  variety  of  conditions.  As  the  food  represents 
the  chemical  reservoir  of  potential  energy,  from  which  the  kinetic 
energy  (in  its  various  forms)  and  the  heat  of  the  body  are  obtained, 
the  absolute  amount  of  food  must  be  increased  when  the  body 
loses  more  heat,  as  in  winter,  and  when  more  muscular  activity 
(work)  is  accomplished.  As  a  general  rule  an  adult  requires  daily 
130  grammes  proteids,  84  grammes  fats,  404  grammes  carbohydrates. 


The-foUowing  tables  express  the  mean  of  numerous  single  observations : — 


DAILY  QUANTITY  OF  FOOD  REQUIRED. 
A  Healthy  Adult  Requires  in  24  Hours— 


481 


Food  in  Grammes. 

At  Rest 
(Playfair). 

Moderate 

Work 

(Moleschott). 

Laborious  Work— 

(Playfair). 

(V.  Pettenkofer 
and  V.  Voit ) 

Proteids, 

Fats,    .... 
Carbohydrates   (Sugar, 
Starch,  etc.),     . 

70-87 
28-35 

310-20 

130 
84 

404 

155-92 
70-87 

567-50 

137 
117 

352 

In  an  analogous  example  from  Vierordt,  the  elementary  substances  in  the  food 
are  given  (p.  446),  and  compared  with  the  income  and  expenditure. 

An  Adult  Doing  a  Moderate  Amount  of  Work  Takes  in  :— 


c. 

H. 

N. 

0. 

120  Grammes  Albumin,  containing, 
90        „          Fats 
330        „          Starch              ,, 

64-18 

70-20 

146-82 

8-60 
10-26 
20-33 

18-88 

28-34 

9-54 

162-85 

281-20 

39-19 

18-88 

200-73 

Add  744-11  gnii.  O  from  the  air  by  respiration. 
„     2,818    „  HoO. 

,,  32    ,,  Inorganic  compounds  (Salts). 

The  whole  is  equal  to  3i  kilo.,  i.e.,  about  t,V  of  the  body-weight ;  so  that  about 
6  per  cent,  of  the  water,  about  6  per  cent,  of  the  fat,  about  1  per  cent,  albumin, 
and  about  0-4  per  cent,  of  the  salts  of  the  body  are  daily  transformed  within  the 
organism. 

An  Adult  Doing  Moderate  Work  Gives  off  :— 


. 

Water. 

c. 

H.                   N. 

0. 

By  respiration. 
Transpiration, 
Urine,   . 
Faeces, 

330 

660 

1,700 

128 

248-8 

20 

9-8 

20-0 

3-3 
3-0 

9 

15-8 
3-0 

651-15     1 
7-2 
11-1 
120 

2,818 

281-2 

6-3 

18-8 

681-45 

Add  to  this  (besides  2,818  grammes  water  as  drink),  296  grammes  water 
formed  in  the  body  by  the  oxidation  of  H.  These  296  grammes  of  water  contain 
32,89  grammes  H,  and  263,41  grammes  0;  26  grammes  of  salts  are  given  off  in  the 
urine,  and  6  by  the  fjeces. 

Efifect  of  Age. — The  investigations  of  the  Munich  School  have  shown, 

that  the  following  numbers  represent   the  smallest  amount  of  food 

necessary  for  different  ages  : — 

31 


482 


RELATIVE  PROPORTION  OI*  FOODS  REQUIRED  DAlLY. 


Age, 

Nitrogenous. 

Fat. 

Carbohydrates. 

Child  until  I4  years,    . 

20-36  grm. 

30-45  grm. 

60-90  grm. 

„      from  6-15  years, 

70-80     „ 

37-50    „ 

250-400  „ 

Man  (moderate  work), 

118      „ 

56 

500      „ 

Woman            ,, 

92      „ 

44 

400      „ 

Old  man,     ■        .        .        . 

100      „ 

68 

350      „ 

Old  woman, 

80      „ 

50 

260      „ 

In  most  of  the  ordinary  articles  of  diet,  nitrogenous  and  non- 
nitrogenous  substances  are  present,  but  in  very  varying  proportion  in 
the  different  foods.  Man  requires  that  these  shall  be  in  the  proportion 
of  1  :  3i  to  1  :  4i. 

If  food  be  taken  in  which  this  proportion  is  not  observed,  in  order 
to  obtain  the  necessary  amount  of  that  substance  which  is  contained 
in  too  small  proportion  in  his  food,  he  must  consume  far  too  much 
food.  Moleschott  finds  that  a  person,  in  order  to  obtain  the  130 
grammes  of  proteids  necessary,  must  use 


Cheese, 

388  grm. 

Beef,   . 

614  grm. 

Eice,    . 

.     2,562  grm. 

Lentils, 

.        491     „ 

Eggs, 

968    „ 

Rye  bread, 

.     2,875    „ 

Peas,    . 

.        582    „ 

Wheat  bread. 

1,444    „ 

Potatoes, 

.   10,000    „ 

provided  he  were  to  take  only  one  of  these  substances  as  food;  so  that 
it  is  perfectly  obvious  that  if  a  workman  were  to  live  on  potatoes  alone, 
in  order  to  get  the  necessary  amount  of  N,  he  would  have  to  consume 
an  altogether  preposterous  amount  of  this  kind  of  food. 

To  obtain  the  448  grammes  of  carbohydrates,  or  the  equivalent 
amount  of  fat  (100  :  175),  necessary  to  support  him,  a  man  must  eat 


Rice,    , 

572  grm. 

Peas,  .         , 

819  grm. 

Cheese,      , 

2,011  grm. 

Wheat  bread, 

625    „ 

Eggs, 

902    „ 

Potatoes,  , 

2,039    „ 

Lentils, 

806    „ 

Rye  bread, 

930    „ 

Beef, 

2,261     „ 

So  that  if  he  were  to  live  upon  cheese  or  flesh  alone,  he  would  require 
to  eat  an  enormous  amount  of  these  substances. 

Li  the  case  of  the  herbivora,  the  proportion  of  nitrogenous  to  non-nitrogenous 
food  necessary  is  1  of  the  former  to  8  or  9  parts  of  the  latter. 


237.  Metabolism  during  Hunger  and  Starvation. 

If  a  warm-blooded  animal  be  deprived  of  all  food,  it  must,  in  order 
to  maintain  the  temperature  of  its  body  and  to  produce  the  necessary 
am.ount  of  mechanical  work,  transform  and  utilise  the  potential  energy 
of  the  constituents  of  its  own  body.  The  result  is  that  its  body- 
weight  diminishes  from  day  to  day,  until  death  occurs  from  starvation. 


HUNGER  AND   STARVATION. 


483 


-  In  order  to  investigate  the  condition  of  inanition  it  is  necessary — (1)  to  weigh 
the  animal  daily;  (2)  to  estimate  daily  all  the  C  and  N  given  off  from  the  body 
in  the  faeces,  urme,  and  expired  air.  The  N  and  C,  of  course,  can  only  be 
obtained  from  the  decomposition  of  tissues  containing  them. 

The   following  table  from    Bidder  and   Schmidt  shows  the  amounts   of   the 
different  excreta  in  the  case  of  a  starved  cat : — 


Day. 

Body- 
weight. 

Water 
taken. 

Urine. 

Urea. 

Inorganic 
substances 
in  Urine. 

Dry 
Faeces. 

Expired 
C. 

Water  in 

Urine 
andFeeces. 

1. 

2,464 

98 

7-9 

1-3 

1-2 

13-9 

91-4 

2. 

2,297 

11-5 

54 

5-3 

0-8 

1-2 

12-9 

50-5 

3. 

2,210 

45 

4-2 

0-7 

11 

13 

42-9 

4. 

2,172 

68-2 

45 

3-8 

0-7 

11 

12-3 

43 

5. 

2,129 

55 

4-7 

0-7 

1-7 

11-9 

54-1 

6. 

2,024 

44 

4-3 

0-6 

0-6 

11-6 

41-1 

7. 

1,946 

40 

3-S 

0-5 

0-7 

11 

37-5 

8. 

1,873 

42 

3-9 

0-6 

1-1 

10-6 

40 

9. 

1,782 

15-2 

42 

4 

0-5 

1-7 

10-6 

41-4 

10. 

1,717 

35 

3-3 

0-4 

1-3 

10-5 

34 

11. 

1,695 

4 

32 

2-9 

0-5 

1-1 

10-2 

30-9 

12. 

1,634 

22-5 

30 

2-7 

0-4 

1-1 

10-3 

29-6 

13. 

1,570 

7-1 

40 

3-4 

0-5 

0-4 

10-1 

36-6 

14. 

1,518 

3 

41 

3-4 

0-5 

0-3 

9-7 

38 

15. 

1,434 

... 

41 

2-9 

0-4 

0-3 

9-4 

38-4 

16. 

1,389 

48 

3 

0-4 

0-2 

8-8 

45-5 

17. 

1,335 

28 

1-6 

0-2 

0-3 

7-8 

26 -G 

is.t 

1,267 

13 

0-7 

0-1 

0-3 

6-1 

12-9 

-1,197 

131-5 

775 

65-9 

9-8 

15-8 

190-8 

734-4 

The  cat  lost  1,197  grm.  in  weight  before  it  died,  and  this  amount 
is  apportioned  in  the  follomng  way:  204-43  grm.  (=17-01  per  cent); 
loss  of  albumin,  132*75  grm.  (=11-05  per  cent.);  loss  of  fat,  863-82 
grm.,  loss  of  water  (=71  "91  per  cent,  of  the  total  body- weight). 

Amongst  the  general  phenomena  of  inanition,  it  is  found  that 
strong,  well-nourished  dogs  die  after  4  weeks,  man  after  21-24  days 
(Moleschott) — (6  melancholies  who  took  water  died  after  41  days) ; 
small  mammals  and  birds,  9  days,  and  frogs  9  months.  Vigorous 
adults  die  when  they  lose  x1>  of  their  body-weight,  but  young 
individuals  die  much  sooner  than  adults. 

The  symptoms  of  inanition  are  obvious: — The  mouth  is  dry,  the 
walls  of  the  alimentary  canal  become  thin,  and  the  digestive  secretions 
cease  to  be  formed,  pulse-beats  and  respirations  are  fewer;  urine 
very  acid  from  the  presence  of  an  increased  amount  of  sulphuric 
and  phosphoric  acids,  whilst  the  chlorine  compounds  rapidly  diminish 


484 


LOSS  OF  WEIGHT  DURING  STARVATION. 


and  almost  disappear.  The  blood  contains  less  water  and  the  plasma 
less  albumin,  the  gall-bladder  is  distended,  which  indicates  a  con- 
tinuous decomposition  of  blood-corpuscles  within  the  liver.  The 
liver  is  small  and  very  dark-coloured,  the  muscles  are  very  brittle 
and  dry,  so  that  there  is  great  muscular  weakness,  and  death  occurs 
with  the  signs  of  great  depression  and  coma. 

The  relations  of  the  metabolism  are  given  in  the  foregoing  table, 
the  diminished  excretion  of  urea  is  much  greater  than  that  of  COg, 
which  is  due  to  a  larger  amount  of  fats  than  proteids  being 
decomposed. 

According  to  the  calculation,  there  is  daily  a  tolerably  constant 
amount  of  fat  used  up,  while,  as  starvation  continues,  the  proteids  are 
decomposed  in  much  smaller  amounts  from  day  to  day,  although 
the  drinking  of  water  accelerates  their  decomposition.  The  excretion 
of  COg  therefore  falls  more  slowly  than  the  total  body-weight,  so 
that  the  unit-weight  of  the  living  animal  from  day  to  day  may 
even  show  an  increased  production  of  COg.  The  amount  of  0 
consumed,  depends  of  course  upon  the  oxidation  of  proteids  (which 
require  less  0),  and  of  fats  (which  require  more  0). 

According  to  D.  Finkler,  starving  animals  consume  nearly  as  much  0  as  well-, 
nourished  animals,  so  that  the  energy  of  oxidation  is  scarcely  altered  during 
inanition.  Corresponding  to  this,  the  temperature  of  a  starving  animal  is  the 
same  as  normal.  The  respiratory  quotient  (p.  255)  falls  from  0'9  to  07,  and  the 
excretion  of  CO2  diminishes  more  rapidly  than  the  consumption  of  O.  It  would 
be  wrong,  however,  to  conclude,  from  the  diminished  condition  of  CO2,  that  the 
oxidation  also  was  diminished,  as  the  simultaneous  consumption  of  0  is  the  only 
guide  to  the  energy  of  the  metabolism.  As  starving  animals  use  up  their  own 
flesh  and  fat,  they  form  less  COj  than  well-nourished  animals  which  oxidise  carbo- 
hydrates. 

Loss  of  weight  of  Organs. — It  is  of  importance  to  determine  to 
what  extent  the  individual  organs  and  tissues  lose  weight;  some 
undergo  simple  loss  of  weight,  e.g.,  the  bones,  the  fat  undergoes  very 
considerable  and  rapid  decomposition,  while  other  organs,  as  the  heart, 
undergo  little  change,  because  they  seem  to  be  able  to  nourish 
themselves  from  the  transformation  products  of  other  tissues. 

A  starving  cat,  according  to  v.  Voit,  lost — 


Per  cent,  of          Per  cent,  of 

the  originally    the  total  loss  of 

present.           body-weight. 

Per  cent,  of 
the  originally 
present. 

Per  cent,  of 

the  total  loss  of 

body-weight. 

1. 

Fat,      . 

97 

26-2 

10, 

Lungs,       .        17-7 

...       0-3 

2. 

Spleen, 

66-7      .. 

0-6 

11. 

Pancreas,           17'0 

...       01 

3. 

Liver, 

53-7      .. 

4-8 

12. 

Bones,        .        13-9 

...       5-4 

4. 

Testicles, 

40-0      .. 

.       0-1 

13. 

Central  Nervous 

5. 

Muscles, 

30-5      .. 

42-2 

System,               3-2 

...       01 

6. 

Blood, 

27-0      .. 

3-7 

14. 

Heart,         .         2*6 

0-02 

7. 

Kidneys, 

25-9 

0-6 

15. 

Total   loss   of 

8. 

Skin, 

20-6 

8-8 

the  rest  of  the 

9. 

Intestine,     . 

18-0      ... 

20 

body,           .       36-8 

..       50 

.  METABOLISM   DURING   A  FLESH  DIET.  485 

There  is  a  very  important  difference  according  as  the  animals  before 
inanition  have  been  fed  freely  on  flesh  and  ftit,  or  as  they  have 
merely  had  a  subsistence  diet.  Well-fed  animals  lose  weight  much 
more  rapidly  during  the  first  few  days  than  on  the  later  days.  v.  Voit 
thinks  that  the  albumin  derived  from  the  excess  of  food  occurs 
in  a  state  of  loose  combination  in  the  body  as  "circulating"  or 
"storage-albumin,"  so  that  during  hunger,  it  must  decompose  more 
readily  and  to  a  greater  extent  than  the  "organ-albumin"  which 
forms  an  integral  part  of  the  tissues  (p.  477).  Further,  in  fat  indi- 
viduals, the  decomposition  of  fat  is  much  greater  than  in  slender 
persons. 

238.  Metabolism  during  a  purely  Flesh  Diet— 
Albumin  or  Gelatin. 

A  man  is  not  able  to  maintain  his  metabolism  in  equilibrium  on 
a  purely  flesh  diet ;  if  he  were  compelled  to  live  on  such  a  diet,  he 
would  succumb.  The  reason  is  obvious.  In  beef,  the  proportion  of 
nitrogenous  to  non-nitrogenous  elementary  constituents  of  food  is  1:1*7 
(p.  480).  A  healthy  person  excretes  280  grammes  of  carbon,  in  the 
form  of  COq,  in  the  expired  air  and  in  the  urine  and  faeces.  If  a  man 
is  to  obtain  280  grammes  C  from  a  flesh  diet  he  must  consume — 
digest  and  assimilate — more  than  2  kilos,  of  beef  in  24  hours.  But 
our  digestive  organs  are  unequal  to  this  task  for  any  length  of  time. 
The  person  is  soon  obliged  to  take  less  beef,  which  would  necessitate 
the  using  of  his  own  tissues,  at  first  the  fatty  parts  and  afterwards 
the  proteid  substances. 

A  carnivorous  animal  (dog),  whose  digestive  apparatus,  being  specially  adapted 
for  the  digestion  of  flesh,  has  a  short  intestine,  and  powerfully  active  digestive 
fluids,  can  only  maintain  its  metabolism  in  a  state  of  equilibrium  when  fed  on  a 
flesh  diet  free  from  fat,  provided  its  body  is  already  well  supplied  with  fat,  and 
is  muscular.  It  consumes  ^  to  tjV  P^''^  o^  ^^^  weight  of  its  body  in  flesh,  so  that 
the  excretion  of  urea  increases  enormously.  If  it  eats  a  larger  amount,  it  may 
"  put  on  flesh,"  when,  of  course,  it  requires  to  eat  more  to  maintain  itself  in  this 
condition,  until  the  limit  of  its  digestive  activity  is  reached.  If  a  well -nourished 
dog  is  fed  on  less  than  -^  to  -nV  of  its  body-weight  of  flesh,  it  uses  part  of  its 
own  fat  and  muscle,  gradiially  diminishes  in  weight,  and  ultimately  succumbs. 
Poorly  fed  non-muscular  dogs  are  unable  from  the  very  beginning  to  maintain 
their  metabolism  in  equilibrium  for  any  length  of  time  on  a  purely  flesh  diet,  as 
they  must  eat  so  large  a  quantity  of  flesh,  that  their  digestive  organs  cannot  digest 
it.  The  herbivora  cannot  live  upon  flesh  food,  as  their  digestive  apparatus  is 
adapted  solely  for  the  digestion  of  vegetable  food. 

Exactly  the  same  result  occurs  with  other  forms  of  proteids,  as 
with  flesh.  It  has  been  proved  that  gelatin  may  to  a  certain  extent 
replace  proteids  in  the  food,  in  the  proportion  of  2  of  gelatin  to  I  of 


486         DIET  OF  PURE  FAT  OR  CARBOHYDRATES. 

albumin.  The  carnivora  which  can  maintain  their  metabolism  in 
equilibrium  by  eating  a  large  amount  of  flesh,  can  do  so  with  less 
flesh  when  gelatin  is  added  to  their  food.  A  diet  of  gelatin  alone, 
which  produces  much  urea,  is  not  sufficient  for  this  purpose,  and 
animals  soon  lose  their  appetite  for  this  kind  of  food  (v.  BischoflF,  v. 
Voit,  V.  Pettenkofer,  Oerum). 

Owing  to  the  great  solubility  of  gelatin,  the  value  of  gelatin  as  a  food  used 
to  be  greatly  discussed,  and  now  again  the  addition  of  gelatin  in  the  form  of 
calf's-foot  jelly  is  recommended  to  invalids.  When  chondrin  is  given  along  with 
flesh  for  a  time,  grape-sugar  is  found  in  the  urine  (Bbdeker). 

239.    A  Diet  of  Fat  or  of  Carbohydrates. 

If  fat  alone  be  "given  as  a  food,  the  animal  lives  but  a  short  time. 
The  animal  so  fed  secretes  even  less  urea  than  when  it  is  starving ; 
so  that  the  consumption  of  fat  limits  the  decomposition  of  the  animal's 
own  proteids.  This  depends  upon  the  fact  that,  fat  being  an  easily- 
oxidised  body,  yields  heat  chiefly,  and  becomes  sooner  oxidised  than 
the  nitrogenous  proteids  which  are  oxidised  with  more  difficulty.  If 
the  amount  of  fat  taken  be  very  large,  all  the  0  of  the  fat  does  not 
reappear,  e.g.,  in  the  COg  of  the  expired  air ;  so  that  the  body  must 
acquire  fat,  whilst  at  the  same  time  it  decomposes  proteids.  The 
animal  thus  becomes  poorer  in  proteids  and  richer  in  fats  at  the  same 
time. 

When  carbohydrates  alone  are  'given,  they  must  first  be  converted 
by  the  act  of  digestion  into  sugar.  The  result  of  such  feeding 
coincides  pretty  nearly  with  the  results  of  feeding  with  fat  alone. 
But  the  sugar  is  more  easily  burned  or  oxidised  within  the  body 
than  the  fat,  and  17  parts  of  a  carbohydrate  are  equal  to  10  parts 
of  fat.  Thus  the  diet  of  carbohydrates  limits  the  excretion  of 
urea  more  readily  than  a  purely  fat  diet.  The  animals  lose  flesh 
and  appear  even  to  use  up  part  of  their  own  fat. 

The  direct  introduction  of  grape-sugar  and  cane-sugar  into  the  blood  does  not 
increase  the  amount  of  oxygen  used,  although  the  amount  of  CO2  formed  is 
increased  (Wolfers). 

240.  Mixture  of  Flesh  and  Fat, 

or  of  Flesh  and  Carbohydrates. 

Since  an  amount  of  flesh  equal  to  -h—h  of  the  weight  of  the 
body  is  required  to  nourish  a  dog,  which  is  fed  on  a  purely  flesh 
diet,  if  the  necessary  amount  of  fat  or  carbohydrates  be  added  to 
the  diet,  a  quantity  of  flesh  three  or  four  times  less  is  required.  A 
carbohydrate  has  a  greater  effect  in  diminishing  the  amount  of  urea 


DIET  OF  MIXTURE  OF  FLESH  AND  FAT.  487 

excreted,  than  a  quantity  of  fat,  which  requires  the  same  amount  of  0 
to  oxidise  it,  as  is  required  by  the  amount  of  carbohydrates  con- 
sumed. When  the  amount  of  flesh  is  insufficient,  the  addition  of  fat 
or  carbohydrates  to  the  food  always  limits  the  decomposition  of  the 
animal's  own  substance.  Lastly,  when  too  much  flesh  is  given  along 
with  these  substances,  the  weight  of  the  body  increases  more  with 
them  than  without  them.  Under  these  circumstances,  the  animal's 
body  puts  on  more  fat  than  flesh. 

The  consumption  of  0  in  the  body  is  regulated  by  the  mixture 
of  flesh  and  non-nitrogenous  substances,  rising  and  falling  with  the 
amount  of  flesh  consumed.  It  is  remarkable  that  more  0  is  con- 
sumed when  a  given  amount  of  flesh  is  taken,  than  when  the  same 
amount  of  flesh  is  taken  with  the  addition  of  fat  (v.  Pettenkofer 
and  V.  Voit). 

It  seems  that  instead  of  fat,  the  corresponding  amount  of  fatty  adds  has  the 
same  effect  on  the  metabolism.  They  are  absorbed  as  an  emulsion  just  like  the 
fats.  When  so  absorbed,  they  seem  to  be  reconverted  iiato  fats  in  theii-  passage 
from  the  intestine  to  the  thoracic  duct  (J.  Munk,  Will).  Glycerin  does  not 
diminish  the  decomposition  of  albumin  within  the  body  (Lewin,  Tschirwinsky, 
J.  Munk).  According  to  Lebedeff  and  v.  Voit,  it  diminishes  the  decomposition  of 
the  fats,  and  is  therefore  a  food. 

241.  Origin  of  Fat  in  the  Body. 

I.  Part  of  the  fat  of  the  body  is  derived  directly  from  the  food,  i.e., 
it  is  absorbed  and  deposited  in  the  tissues.  This  is  shown  by  the  fact 
that,  with  a  diet  containing  a  small  amount  of  albumin,  the  addition  of 
more  fat  causes  the  deposition  of  a  larger  amount  of  fat  in  the  body 
(v.  Voit,  Hofmann). 

Lebedefif  found  that  dogs,  which  were  starved  for  a  month,  so  as  to  get  rid  of 
all  their  own  fat,  on  being  fed  with  linseed  oil  or  mutton  suet  and  flesh,  had  these 
fats  restored  to  their  tissues.  These  fats,  therefore,  must  have  been  absorbed 
and  deposited. 

II.  A  second  source  of  the  fats  is  their  formation  from  albuminous 
bodies  (Liebig  and  others). 

In  the  case  of  the  formation  of  fat  from  proteids,  which  may  yield 
1 1  per  cent,  of  fat,  these  proteids  split  up  into  a  non-nitrogenous  and  a 
nitrogenous  atomic  compound.  The  former,  during  a  diet  containing 
much  albumin,  when  it  is  not  completely  oxidised  into  COg,  and  H,0,  is 
the  substance  from  which  the  fat  is  formed — the  latter  leaves  the  body 
oxidised  chiefly  to  the  stage  of  urea  (Hoppe-Seyler,  Fiirsteuberg,  v. 
Voit,  v.  Pettenkofer). 

Examples. — That /a<s  are  formed  from  proteids  is  shown  by  the  following  : — 1. 
A  cow  which  produces  1  lb.  of  butter  daily,  does  not  take  nearly  this  amount  of 


488  ORIGIN  OF  FAT  IN  THE  BODY. 

fatty  matter  in  its  food,  so  that  the  fat  would  appear  to  be  formed  from  vegetable 
proteids.  2.  Carnivora  giving  suck,  when  fed  on  plenty  of  flesh  and  some  fat, 
yield  milk  rich  in  fat.  3.  Dogs  fed  with  plenty  of  flesh  and  some  fat,  add  more 
fat  to  their  bodies  than  the  fat  contained  in  the  food.  4.  Fatty  degeneration,  e.g., 
of  nerve  and  muscle,  is  due  to  a  decomposition  of  proteids.  5.  The  transformation 
of  entire  bodies,  e.g.,  such  as  have  lain  for  a  long  time  surrounded  with  water,  into 
a  mass  consisting  almost  entirely  of  palmitic  acid  (the  adipocere  of  Fourcroy),  is 
also  a  proof  of  the  transformation  of  part  of  the  proteids  into  fata.  6.  Fungi  are 
also  able  to  form  fat  from  albumin  during  their  growth  (v.  Naegeli,  and  0.  Low). 

Fats  not  merely  a1)S0rbed. — Experiments  which  go  to  show  that  the  fat  of 
animals,  during  the  fattening  process,  is  not  absorbed  as  such,  from  the  food  : — 1, 
Fattening  occurs  with  flesh  and  soaps  ;  it  is  most  improbable  that  the  soaps  are 
retransformed  into  neutral  fats  by  taking  up  glycerin  and  giving  up  alkali 
(Kiihne  and  Radziejewski).  2.  If  a  lean  dog  be  fed  with  flesh  and  pabnitin-of 
stearin-soda-soap,  the  fat  of  its  body  contains  in  addition  to  palmitin  and  stearin, 
olein  fat ;  so  that  the  last  must  be  formed  by  the  organism  from  the  proteids  of  the 
flesh.  Further,  Ssubotin  found  that,  when  a  lean  dog  was  fed  on  lean  meat  and 
spermaceti-fat,  a  very  small  amount  of  the  latter  was  found  in  the  fat  of  the 
animal.  Although  these  experiments  show,  that  the  fat  of  the  body  must  be 
formed  from  the  decomposition  of  proteids,  they  do  not  prove  that  all  the  fat 
arises  in  this  way,  and  that  none  of  it  is  absorbed  and  redeposited. 

III.  According  to  v.  Voit,  no  fat  is  formed  in  the  body  directly,  e.g., 
by  reduction  from  carbohydrates.  As  fattening  occurs  on  a  diet  of  pure 
flesh  with  the  addition  of  carbohydrates,  we  must  assume  that  the 
carbohydrates  are  consumed  or  oxidised  in  the  body,  and  that,  thereby, 
a  non-nitrogenous  body  derived  from  the  proteids  is  prevented  from 
being  burned  up,  and  that  it  is  changed  into  fat  and  stored  up  as 
such. 

From  experiments  upon  animals,  however,  Lawes,  Lehmann,  Heiden, 
V.  Wolff,  think  they  are  entitled  to  conclude  that  the  carbohydrates 
absorbed  are  directly  concerned  in  the  formation  of  fats,  a  view  which  is 
supported  by  Henneberg,  B.  Schulze,  Gilbert  and  Soxhlet.  According 
to  Pasteur,  glycerine  (the  basis  of  neutral  fats)  may  be  formed  from 
carbohydrates. 

Formerly  it  was  believed  that  bees  could  prepare  wax  from  honey  alone;  this  is 
a  mistake — an  equivalent  of  albumin  is  required  in  addition — the  necessary  amount 
is  found  in  the  raw  honey  itself. 


242.  Corpulence. 


The  addition  of  too  much  fat  to  the  body  is  a  pathological  phenomenon  which 
is  attended  with  disagreeable  consequences.  With  regard  to  the  caUSes  of 
obesity,  without  doubt  there  is  an  inherited  tendency  (in  33-56  per  cent,  of  the 
cases — Bouchard,  Chalmers)  in  many  families — and  in  some  breeds  of  cattle — to 
lay  up  fat  in  the  body,  while  other  families  may  be  richly  supplied  with  fat,  and 
yet  remain  lean.  The  chief  cause,  however,  is  taking  too  much  food,  i.e.,  more 
than  the  amount  required  for  the  normal  metabolism;  corpulent  people,  in  order 
to  maintain  their  bodies,  must  eat  absolutely  and  relatively  more  than  persons  of 
spare  habit,  under  analogous  conditions  of  nutrition  (p.  477). 


CORPULENCE,  489 

COttditionS  favouring  Corpulence.— The  following  conditions  favour  the 
occurrence  of  corpulence:— (1)  A  diet  rich  in  proteids,  with  a  corresponding 
addition  oifat  or  carbohydrates.  As  flesh  or  muscle  is  formed  from  proteids,  and 
part  of  the  fat  of  the  body  is  also  formed  from  albumin  (j).  487),  the  assumption 
that  fats  and  carbohydrates  fatten,  or  when  taken  alone,  act  as  fattening  agents, 
is  completely  without  foundation.  No  one  ever  becomes  fat  without  taking 
plenty  of  albumin.  (2)  Diminished  disintegration  of  materials  within  the  body — 
e.g.  (a)  diminished  muscidar  activity  (much  sleep  and  little  exercise);  (6)  abroga- 
tion of  the  sexual  furxtions  (as  is  shown  by  the  rapid  fattening  of  castrated 
animals,  as  well  as  by  the  fact  that  some  women,  after  cessation  of  the  menses, 
readily  become  corpulent) ;  (c)  diminished  mental  activity  (the  obesity  of  dementia), 
phlegmatic  temperament.  On  the  contrary,  vigorous  mental  work,  excitable 
temperament,  care  and  sorrow,  comiteract  the  deposit  of  fat;  (d)  diminished  extent 
of  the  respiratory  activity,  as  occurs  when  there  is  a  great  deposition  of  fat  in  the 
abdomen,  limiting  the  action  of  the  diaphragm  (breathlessness  of  corpulent 
people),  whereby  the  combustion  of  the  fatty  matters,  which  become  deposited  in 
the  body,  is  hmited ;  (e)  a  corpulent  person  requires  to  use  relatively  less  heat- 
giving  substances  in  his  body,  partly  because  he  gives  off  relatively  less  heat  from 
his  compact  body,  than  is  done  by  a  slender  long-bodied  individual,  and  partly 
because  the  thick  layer  of  fat  retards  the  conduction  of  heat  (p.  444).  Thus 
corresponding  to  the  relatively  diminished  production  of  heat,  more  fat  may  be 
stored  up;  (/)  a  diminution  of  the  red  blood-corpuscles,  which  are  the  great 
exciters  of  oxidation  in  the  body,  is  generally  followed  by  an  increase  of  fat — fat 
people,  as  a  rule,  are  fat  because  they  have  relatively  less  blood  (p.  63) — "women 
with  fewer  red  blood-corpuscles  are  usually  fatter  than  men;  {g)  the  consumption 
of  alcohol  favours  the  conservation  of  fat  in  the  body,  the  alcohol  is  easily  oxidised, 
and  thus  prevents  the  fat  from  being  burned  up  ( §  235). 

Well-nourished  individuals  are  usually  at  first  both  muscular  and  endowed 
with  a  fair  amount  of  fatty  tissue.  When  they  begin  to  put  on  fat,  the  develop- 
ment of  the  muscular  sj'stem  lags  behind,  partly  because  the  increasing  corpulence 
leads  to  diminished  activity  of  the  muscular  system,  so  that  this  sj'stem  is 
involved  secondarily.  Some  lively  corpulent  people,  nevertheless,  retain  their 
muscular  energy.  When  those  conditions  which  favour  corpulence  are  specially 
active,  corpulence  may  ultimately  pass  into  a  condition  of  great  obesity. 

Besides  the  inconvenience  of  the  great  size  and  weight  of  the  body,  corpulent 
people  suffer  from  breathlessness — they  are  easily  fatigued,  are  liable  to  intertrigo 
between  the  folds  of  the  skin,  the  heart  becomes  loaded  with  fat,  and  they  not 
unfrequently  are  subject  to  apoplexy. 

Inorderto  counteract  corpulence  we  ought  to— (1)  Reduce  uniformly  allarticles 
of  diet.  The  diet  and  body  ought  to  be  weighed  from  week  to  week,  and  as  long 
as  there  is  no  diminution  in  the  body-weight  the  amount  of  food  ought  to  be 
gradually  and  uniformly  reduced  (notwithstanding  the  appetite).  This  must  be 
done  very  gradually  and  not  suddenly.  It  is  not  advisable  to  limit  the  amount 
of  fat  and  carbohydrates  alone,  as  is  done  in  the  Banting-cure  or  Bantingism. 
Apart  altogether  from  the  fact  that  fat  is  formed  from  proteids,  if  too  little  non- 
nitrogenous  food  be  taken,  severe  disturbance  of  the  bodily  metabolism  is  apt  to 
occur.  (2)  The  muscular  activity  ought  to  be  greatly  developed  by  doing  plenty  of 
muscular  work,  or  taking  plenty  of  exercise,  both  physical  and  mental.  (3)  Favour 
the  evolution  of  heat  by  taking  cold  baths  of  considerable  duration,  and  afterwards 
rubbing  the  skLu  strongly  so  as  to  cause  it  to  become  red;  farther,  dress  lightly; 
and  at  night  use  light  bed-clothing ;  tea  and  coffee  are  useful,  as  they  excite  the 
circulation.  (4)  Use  gentle  laxatives;  acid  fruits,  cider,  alkaline  carbonates 
(Marienbad,  Carlsbad,  Vichy,  Neuenahr,  Ems,  &c.).  The  copious  drinking  of 
water  is  also  serviceable,  as  it  favours  the  metabolism. 

Fatty  Degeneration.— The  process  of  fattening  consists  in  the  deposition  of 


490  METABOLISM  OF  THE  TISSUES. 

drops  of  fat  within  the  fat-cells  of  the  panniculus  and  around  the  viscera,  as  well 
as  in  the  marrow  of  bone  (but  they  are  never  deposited  in  the  subcutaneous  tissue 
of  the  eyelids,  of  the  penis,  of  the  red  part  of  the  lips,  in  the  ears  and  nose). 
This  is  quite  different  from  the  fatty  atrophy  or  fatty  degeneration  which 
occurs  in  the  form  of  fatty  globules  or  granules  ia  albuminous  tissues — e.g.,  in 
muscular  fibres  (heart),  gland-cells  (liver,  kidney),  cartilage-cells,  lymph-  and 
pus-corpuscles,  as  well  as  in  nerve-fibres  separated  from  their  nerve-centres 
The  fat  in  these  cases  is  derived  from  albumin,  much  in  the  same  way  as  fat  is 
formed  in  the  gland-cells  of  the  mammary  and  sebaceous  glands.  Marked  fatty 
degeneration  not  unfrequently  occurs  after  severe  fevers,  and  after  artificial  heating 
of  the  tissues;  when  a  too  small  amount  of  O  is  supplied  to  the  tissues,  as  occurs  in 
cases  of  phosphorus  poisoning  (Bauer);  in  drunkards;  after  poisoning  with  arsenic 
and  other  substances;  and  after  some  disturbances  of  the  circulation  and  inner- 
vation. Some  organs  are  especially  prone  to  undergo  fatty  degeneration  during  the 
course  of  certain  diseases. 


243.   The  Metabolism  of  the  Tissues. 

The  blood-stream  is  the  chief  medium  whereby  new  material  is 
supplied  to  the  tissues  and  the  effete  products  removed  from  them. 
The  lymfh  which  passes  through  the  thin  capillaries,  comes  into  actual 
contact  with  the  tissue  elements.  Those  tissues  which  are  devoid 
of  blood-vessels  in  their  own  substance,  such  as  the  cornea  and 
cartilage,  receive  nutrient  fluid  or  lymph  from  the  adjacent  capillaries, 
by  means  of  their  cellular  elements  which  act  as  juice-conducting 
media.  Hence,  when  the  normal  circulation  is  interfered  with,  as 
by  atheroma  or  calcification  of  the  walls  of  the  blood-vessels,  these 
tissues  are  secondarily  affected  [this,  for  example,  is  the  case  in  arcus 
senilis  of  the  cornea,  due  to  a  fatty  degeneration  of  the  corneal 
tissue,  owing  to  some  affection  of  the  blood-vessels  on  which  the 
cornea  depends  for  its  nutrition].  Total  compression  or  ligature 
of  all  the  blood-vessels,  results  in  necrosis  of  the  parts  supplied  by 
the  ligatured  blood-vessels. 

Hence,  there  must  be  a  double  current  of  the  tissue  juices;  the 
afferent  or  supjply  current,  which  supplies  the  new  material,  and  the 
efferent  stream  which  removes  the  effete  products.  The  former  brings 
to  the  tissues  the  proteids,  fats,  carbohydrates  and  salts  from  which 
the  tissues  are  formed.  That  such  a  current  exists  is  proved  by 
injecting  an  indifferent,  easily  recognisable  substance  into  the  blood, 
e.g.,  potassium  ferrocyanide,  when  its  presence  may  be  detected  in 
the  tissues,  to  which  it  has  been  carried  by  the  out-going  current. 
The  efferent  stream  carries  away  the  decomposition  products  from 
the  various  tissues,  more  especially  urea,  COg,  HgO  and  salts,  and 
these  are  transferred  as  quickly  as  possible  to  the  organs  through 
which  they  are  excreted.  That  such  a  current  exists  is  proved  by 
injecting  such  a  substance  as  potassium  ferrocyanide  into  the  tissues, 


METABOLISM  OF  THE  TISSUES.  491 

e.g.y  subcutaneously,  when  its  presence  may  bo  detected  in  the  urine 
within  2  to  5  minutes.  If  the  current  from  the  tissues  to  the  blood 
is  so  active  that  the  excretory  organs  cannot  eliminate  all  the 
effete  products  from  the  blood,  then  these  products  are  found  in 
the  tissues.  This  occurs  when  certain  poisons  are  injected  vsub- 
cutaneously,  when  they  pass  rapidly  into  the  blood  and  are  carried 
in  great  quantity  to  other  tissues,  e.g.,  to  the  nervous  system,  on 
which  they  act  with  fatal  effect,  before  they  are  eliminated  to  any 
great  extent  from  the  blood,  by  the  action  of  the  excretory  organs. 

The  effete  materials  are  carried  away  from  the  tissues  by  ttoo 
channels,  viz.,  by  the  veins  and  by  the  lymphatics,  so  that  if  these 
be  interfered  with,  the  metabolism  of  the  tissues  must  also  suffer. 
When  a  limb  is  ligatured  so  as  to  compress  the  veins  and  the 
lymphatics,  the  efferent  stream  stagnates  to  such  an  extent  that 
considerable  swelling  of  the  tissues  may  occur  (oedema,  p.  419.) 

H.  Nasse  found,  that  the  blood  of  the  jugular  vein  is  0*225  per  1000  specifically 
heavier  than  the  blood  of  the  carotid,  and  contains  0"9  parts  per  1000  more  solids; 
1000  cubic  centimetres  of  blood  circulating  through  the  head  yield  about  5  cubic 
centimetres  of  transudation  into  the  tissues. 

The  extent  and  intensity  of  the  metabolism  of  the  tissues  depend 
upon  a  variety  of  factors. 

1.  Upon  their  activity. — The  increased  activity  of  an  organ  is 
indicated  by  the  increased  amount  of  blood  going  to  it,  and  by  the 
more  active  circulation  through  it  (§100).  When  an  organ  is 
completely  inactive,  such  as  a  paralysed  muscle,  or  the  peripheral  end 
of  a  divided  nerve,  the  amount  of  blood  and  the  nutritive  exchange 
of  fluids  diminish  within  these  parts.  The  parts  thus  thrown  out 
of  activity  become  pale,  relaxed,  and  ultimately  undergo  fatty 
degeneration.  The  increased  metabolism  of  an  organ  during  its 
activity  has  been  proved  experimentally  in  the  case  of  muscle,  and 
also  in  the  brain  (Speck). 

Langley  and  Sewell  have  recently  observed  directly  the  metabolic 
changes  within  sufficiently  thin  lobules  of  glands  during  life.  The 
cells  of  serous  glands  (p.  283),  and  those  of  mucous  and  pepsin- 
forming  glands  (p.  327),  during  quiescence,  become  filled  with  coarse 
granules  which  are  dark  in  transmitted  light,  and  white  in  reflected 
light,  which  granules  are  consumed  or  disappear  during  glandular 
activity.  During  sleep,  when  most  organs  are  at  rest,  the  metabolism 
is  limited ;  darkness  also  diminishes  it,  while  light  excites  it,  obviously 
owing  to  nervous  influence.  The  variations  in  the  total  metabolism 
of  the  body  are  reflected  in  the  excretion  of  COg  and  urea,  which 
may  be  expressed  graphically  in  the  form  of  a  curve  corresponding 


492  METABOLISM  OF  THE  TISSUES. 

with  the  activity  of  the  organism ;  this  curve  corresponds  very  closely 
with  the  daily  variations  in  the  respirations,  pulse,  and  temperature. 

2.  The  composition  or  quality  of  the  Wood  has  a  marked  effect 
upon  the  current  on  which  the  metabolism  of  the  tissues  depends. 
Very  concentrated  blood,  which  contains  a  small  amount  of  water, 
as  after  profuse  sweating,  severe  diarrhoea,  e.g.,  in  cholera,  makes 
the  tissues  dry,  while  if  much  water  be  absorbed  into  the  blood,  the 
tissues  become  more  succulent  and  even  oedema  may  occur.  When 
much  common  salt  is  present  in  the  blood  and  when  the  red  blood- 
corpuscles  contain  a  diminished  amount  of  0,  and  especially  if  the 
latter  condition  be  accompanied  by  muscular  exertion  causing  dyspnoea, 
a  large  amount  of  albumin  is  decomposed,  and  there  is  a  great 
formation  of  urea.  Hence,  exposure  to  a  rarified  atmosphere  is 
accompanied  by  increased  excretion  of  urea  (Frankel,  Penzoldt,  and 
R.  Fleischer).  Certain  abnormal  conditions  of  the  blood  produce 
remarkable  results;  blood  charged  with  carbonic  oxide  cannot  absorb 
0  from  the  air,  and  does  not  remove  COg  from  the  tissues  (compare 
p.  31).  The  presence  of  hydrocyanic  acid  in  the  blood  (p.  33),  is  said 
to  interrupt  at  once  the  chemical  oxidation  processes  in  the  blood 
(Mialhe),  so  that  rapid  asphyxia,  owing  to  cessation  of  the  internal 
respiration,  occurs  (Ed.  Wagner).  Fermentation  is  interrupted  by  the 
same  substance  in  a  similar  way.  A  diminution  of  the  total  amount  of 
the  blood  causes  more  fluid  to  pass  from  the  tissues  into  the  blood 
(p.  63),  but  the  absorption  of  substances — such  as  poisons  or  patho- 
logical effusions  (Kaup),  from  the  tissues  or  intestines  is  delayed. 
If  the  substances  which  pass  from  the  tissues  into  the  blood  be 
rapidly  eliminated  from  it,  absorption  takes  place  more  rapidly. 

3.  The  blood-pressure  is  of  importance  in  so  far  that,  when  it  is 
greatly  increased,  the  tissues  contain  more  fluid,  while  the  blood 
itself  becomes  more  concentrated,  to  the  extent  of  3-5  per  1000 
(Nasse).  We  may  convince  ourselves  that  blood-plasma  easily  passes 
through  the  capillary  wall,  by  pressing  upon  the  efi'erent  vessel 
coming  from  the  chorium  deprived  of  its  epidermis,  e.g.,  by  a  burn 
or  a  bhster,  when  the  surface  of  the  wound  becomes  rapidly  suffused 
with  plasma.  Diminution  of  the  blood-pressure  produces  the  opposite 
result. 

4.  Increased  temperature  of  the  tissues  favours  the  metabolism, 
so  that  the  excretion  of  COg  and  the  production  of  urea  are  increased 
(§§  220,  221);  while  diminution  of  the  temperature  has  the  opposite 
result  (§225). 

5.  The  influence  of  the  Nervous  system  on  the  metabolism  is 
twofold.  On  the  one  hand,  it  acts  indirectly  through  its  effect  upon 
the  blood-vessels,  by  causing  them  to  contract  or  dilate  through  the 


REGENERATION   OF  ORGANS   AND  TISSUES.  493 

agency  of  vaso-mofor  nerves,  whereby  it  influences  the  amount  of  blood 
supplied,  and  also  afi'ects  the  blood-pressiire.  But  in  addition  to  this, 
and  quite  independently  of  the  blood-vessels,  it  is  probable  that  certain 
special  nerves — the  so-called  trophic  nerves,  influence  the  metabolism  or 
nutrition  of  the  tissues  (see  Trophic  Nerves),  That  nerves  do 
influence  directly  the  transformation  of  matter  within  the  tissues  is 
shown  by  the  secretion  of  saliva  resulting  from  the  stimulation  of 
certain  nerves,  after  cessation  of  the  circulation  (p.  287),  and  by 
the  metabolism  during  the  contraction  of  bloodless  muscles.  Increased 
respiration  and  apnoea  are  not  followed  by  increased  oxidation  (Pfliiger) 
(compare  p.  259). 

244.  Regeneration  of  Organs  and  Tissues. 

The  extent  to  which  lost  parts  are  replaced  varies  greatly  in  different  organs. 
Amongst  the  lOiver  animals,  the  parts  of  organs  are  replaced  to  a  far  greater 
extent  than  amongst  warm-blooded  animals.  When  a  hydra  is  divided  into  two 
parts,  each  part  forms  a  new  individual — nay,  if  the  body  of  the  animal  be 
divided  into  several  parts  in  a  particular  way,  then  each  part  gives  rise  to  a 
new  individual  (Spallanzani),  The  Planarians  also  show  a  great  capability 
of  reproducing  lost  parts  (Dugfes).  Spiders  and  crabs  can  reproduce  lost 
feelers,  limbs,  and  claws ;  snails,  part  of  the  head,  feelers,  and  eyes,  provided  the 
central  nervous  system  is  not  injured.  Many  fishes  reproduce  tins,  even  the  tail- 
tin.  Salamanders  and  lizards  can  produce  an  entire  tail,  including  bones,  muscles, 
and  even  the  posterior  part  of  the  spinal  cord;  while  the  triton  reproduces  an 
amputated  limb,  the  lower  jaw,  and  the  eye.  This  reproduction  necessitates  that 
a  small  stump  be  left,  while  total  extirpation  of  the  parts  prevents  reproducbion 
(Philippeaux). 

In  amphibians  and  reptiles,  the  regeneration  of  organs  and  tissues  as  a  whole, 
takes  place  after  the  type  of  the  embryonic  development  (Fraisse,  Gotte),  and  the 
same  is  true  as  regards  the  histological  processes  which  occur  in  the  regenerated 
tail  and  other  parts  of  the  body  of  the  earth-worm  (Bulow). 

The  extent  to  which  regeneration  can  take  place  in  mammals  and  in 
man  is  very  slight,  and  even  in  these  cases,  it  is  chiefly  confined  to 
young  individuals.     A  true  regeneration  occurs  in — 

1.  The  blood  (compare  §  7  and  §  41),  including  the  plasma,  the 
colourless  and  coloured  corpuscles. 

2.  The  epidermal  appendages  (see  Skin,  vol.  ii),  and  the  epithelium  of 
the  mucous  membranes  are  reproduced  by  a  proliferation  of  the  cells  of 
the  deeper  layers  of  the  epithelium,  with  simultaneous  division  of  their 
nuclei.  Epithelial  cells  are  reproduced  as  long  as  the  matrix  on  which 
they  rest  and  the  lowest  layer  of  cells  are  intact.  When  these  are 
destroyed  cell-regeneration  from  beloAv  ceases,  and  the  cells  at  the 
margins  are  concerned  in  filling  up  the  deficiency.  Regeneration, 
therefore,  either  takes  place  from  below  or  from  the  margins  of  the 
wound  in  the  epithelial  covering ;  leucocytes  also  wander  into  the  part, 


494  Regeneration  of  tissues. 

■while  the  deepest  layer  of  cells  forms  large  multi-nucleated  cells  which 
reproduce  by  division  polygonal,  flat  nucleated  cells  (Klebs,  Heller). 
The  nails  grow  from  the  root  forwards ;  those  of  the  fingers  in  4-5 
months,  and  that  of  the  great  toe  in  about  12  months,  although  growth  is 
slower  in  the  case  of  fracture  of  the  bones.  The  matrix  is  co-extensive 
with  the  lunule,  and  if  it  be  destroyed  the  nail  is  not  reproduced 
(see  vol.  ii.).  The  eyelashes  are  changed  in  100  -  150  days 
(Donders),  the  other  hairs  of  the  body  somewhat  more  slowly. 
If  the  papilla  of  the  hair  folHcle  be  destroyed,  the  hair  is  not 
reproduced.  Cutting  the  hair  favours  its  growth,  but  hair  which  has 
been  cut  does  not  grow  longer  than  uncut  hair.  After  hair  has  grown 
to  a  certain  length  it  falls  out.  The  hair  never  grows  at  its  apex 
(Aristotle).  The  epithelial  cells  of  mucous  membranes  and  secretory 
glands  seem  to  undergo  a  regular  series  of  changes  and  renewal.  The 
presence  of  secretory  cells  in  the  milk  (§'231)  and  in  the  sebaceous 
secretion  {vol.  ii.)  proves  this ;  the  spermatozoa  are  replaced  by  the 
action  of  spermatoblasts.  In  catarrhal  conditions  of  mucous  membranes, 
there  is  a  great  increase  in  the  formation  and  excretion  of  new  epithe- 
lium, while  many  ceUs  are  but  indifi"erently  formed  and  constitute  mucous 
corpuscles.  The  crystalline  lens,  which  is  just  modified  epithelium,  is 
reorganised  just  like  epithelium ;  its  matrix  is  the  anterior  wall  of  its 
capsule,  with  the  single  layer  of  cells  covering  it.  If  the  lens  be 
removed  and  this  layer  of  cells  retained,  these  cells  proliferate  and 
elongate  to  form  lens  fibres,  so  that  the  whole  cavity  of  the  empty  lens 
capsule  is  refilled.  If  much  water  be  withdrawn  from  the  body,  the 
lens  fibres  become  turbid  (Kunde,  Koehnhom).  [A  turbid  or  opaque 
condition  of  the  lens  may  occur  in  diabetes,  or  after  the  transfusion  of 
strong  common  salt  or  sugar  solution  into  a  frog.] 

3.  The  blood-vessels  undergo  extensive  regeneration,  and  they 
are  regenerated  in  the  same  way  as  they  are  formed  (p.  13). 
Capillaries  are  always  the  first  stage,  and  around  them  the  characteristic 
coats  are  added  to  form  an  artery  or  a  vein.  When  an  artery  is  injured 
and  permanently  occluded,  as  a  general  rule  the  part  of  the  vessel  up  to 
the  nearest  collateral  branch  becomes  obliterated,  whereby  the  deriva- 
tives of  the  endothelial  lining,  the  connective  tissue-corpuscles  of  the 
wall  and  the  leucocytes  change  into  spindle-shaj)ed  ceUs  and  form  a 
kind  of  cicatricial  tissue.  Blind  and  solid  outshoots  are  always  found 
on  the  blood-vessels  of  young  and  adult  animals,  and  are  a  sign  of  the 
continual  degeneration  and  regeneration  of  these  vessels  (Sigm.  Mayer). 

4.  The  contractile  substance  of  muscle  may  undergo  regeneration 
after  it  has  become  partially  degenerated.  This  takes  place  after  amy- 
loid or  wax-like  degeneration,  such  as  occurs  not  unfrequently  after 
typhus  and  other  severe  fevers.     This  is  chiefly  accomplished  by  an 


REGENERATION  OE  TISSUES.  495 

increase  of  the  muscle  corpuscles.  After  being  compressed,  the  mus- 
cular nuclei  disappear  and  at  the  same  time  the  contractile  contents 
degenerate  (Heidelberg).  After  several  days,  the  sarcolemma  contains 
numerous  nuclei  which  reproduce  new  muscular  nuclei  and  the  con- 
tractile substance  (Kraske,  Erbkam).  In  fibres  injured  by  a  subcu- 
taneous wound,  Neumann  found  that,  after  5-7  days,  there  was  a 
bud-like  elongation  of  the  cut  ends  of  the  fibres,  at  first  without 
transverse  striation,  but  with  striation  ultimately.  If  a  large  extent 
of  a  muscle  be  removed,  it  is  replaced  by  cicatricial  connective- 
tissue. 

Non-Striped  muscular  fibres  are  also  reproduced ;  the  nuclei  of  the 
injured  fibres  divide  after  becoming  enlarged,  and  exhibit  a  well- 
marked  intra-nuclear  plexus  of  fibrils.  The  nuclei  divide  into  two, 
and  from  each  of  these  a  new  fibre  is  formed,  probably  by  the  differen- 
tiation of  the  peri-nuclear  protoplasm. 

5.  After  a  nerve  is  divided,  the  two  ends  do  not  join  at  once  so  as 
to  permit  the  function  of  the  nerve  to  be  established.  On  the 
contrary,  marked  changes  occur  which  are  described  in  vol.  ii.  If  a 
piece  be  cut  out  of  a  nerve-trunk,  the  peripheral  end  of  the  divided 
nerve  degenerates,  the  axial  cylinder  and  the  white  substance  of 
Schwann  disappear.  The  interval  is  filled  up  at  first  with  juicy 
cellular  tissue.  The  subsequent  changes  are  fully  described  in  vol.  ii. 
There  seems  to  be  in  peripheral  nerves  a  continual  disappearance  of 
fibres  by  fatty  degeneration,  accompanied  by  a  consecutive  formation  of 
new  fibres  (Sigm.  Mayer).  The  regeneration  of  peripheral  ganglionic 
cells  is  unknown,  v.  Voit,  however,  observed  that  a  pigeon,  part  of  whose 
brain  was  removed,  had  within  five  months  reproduced  a  nervous  mass 
within  the  skull  consisting  of  medullated  nerve-fibres  and  nerve-cells. 
Eichhorst  and  Naunyn  found  that  in  young  dogs,  whose  spinal  cord 
was  divided  between  the  dorsal  and  lumbar  regions,  there  was  an  ana- 
tomical and  physiological  regeneration  to  such  an  extent  that  voluntary 
movements  could  be  executed.  Vaulair,  in  the  case  of  frogs,  and 
Masius  in  dogs,  found  that  mobility  or  motion  was  first  restored  and 
afterwards  sensibiUty.  Eegeneration  of  the  spinal  ganglia  does  not 
occur. 

6.  If  a  portion  of  a  secretory  gland  be  removed,  as  a  general  rule,  it 
is  not  reproduced.  But  the  bile-ducts  (p.  350),  and  the  pancreatic 
duct  may  be  reproduced  (p.  345).  According  to  Philippeaux  and 
Griffini,  if  part  of  the  spleen  be  removed,  it  is  reproduced  (compare 
p.  207).  Tizzoni  and  Collucci  observed  the  formation  of  new  liver- 
cells  and  bile-ducts  after  injury  to  the  liver. 

7.  Amongst  connective-tissues,  cartilage,  provided  its  perichondrium 
be  not  injured,  reproduces  itself  by  division   of  its  cartilage   cells 


496  REGENERATION  OE  BONE. 

(Legrand,  Ewetzky,  Schklarewsky);    but  usually  when  a  pat-t  of  a 
cartilage  is  removed,  it  is  replaced  by  connective-tissue. 

8.  When  a  tendon  is  divided,  proliferation  of  the  tendon  cells 
occurs,  and  the  cut  ends  are  united  by  connective-tissue. 

9.  The  reproduction  of  bone  takes  place  to  a  great  extent  under 
certain  conditions.  If  the  ai-ticular  end  be  removed  by  excision,  it 
may  be  reproduced,  although  there  is  a  considerable  degree  of 
shortening.  Pieces  of  bone  which  have  been  broken  off  or  sawn  off 
heal  again,  and  become  united  with  the  original  bone  (Jakimowitsch). 
If  a  piece  of  periosteum  be  transplanted  to  another  region  of  the  body, 
it  eventually  gives  rise  to  the  formation  of  new  bone  in  that  locality. 
If  part  of  a  bone  be  removed,  provided  the  periosteum  be  left,  new 
bone  is  rapidly  reproduced;  hence,  the  surgeon  takes  great  care  to 
preserve  the  periosteum  intact  in  all  operations  where  he  wishes  new 
bone  to  be  reproduced.  Even  the  marrow  of  bone,  when  it  is 
transplanted,  gives  rise  to  the  formation  of  bone.  This  is  due  to  the 
osteoblasts  adhering  to  the  osseous  tissue  (P.  Bruns,  MacEwen). 

In  fracture  of  along  bone,  the  periosteum  deposits  on  the  surface  of  the  ends  of 
the  broken  bones,  a  ring  of  substance  which  forms  a  temporary  support,  the 
external  callus.  At  first  this  callus  is  jelly-like,  soft,  and  contains  many  corpuscles, 
but  afterwards,  it  becomes  more  solid  and  somewhat  like  cartilage.  A  similar 
condition  occurs  within  the  bone,  where  an  internal  callus  is  formed.  The 
formation  of  this  temporary  callus  is  due  to  an  inflammatory  proliferation  of  the 
connective -tissue  corpuscles,  and  partly  to  the  osteoblasts  of  the  periosteum  and 
marrow.  According  to  Rigal  and  Vignal,  the  internal  callus  is  always  osseous,  and 
is  derived  from  the  marrow  of  the  bone. 

The  outer  and  inner  callus  becomes  calcified  and  ultimately  ossified,  whereby 
the  broken  ends  are  reunited.  Towards  the  fortieth  day,  a  thin  layer  of  bone  is 
formed  (intermediary  callus)  between  the  ends  of  the  bone.  When  this  begins  to 
be  definitely  ossified,  the  outer  and  inner  callus  begins  to  be  absorbed,  and  ultimately 
the  intermediary  callus  has  the  same  structure  as  the  rest  of  the  bone. 

There  are  many  interesting  observations  connected  with  the  growth  and  meta- 
bolism of  bones.  1.  The  addition  of  a  very  small  amount  of  phosphorus  (Wagner) 
or  arsenious  acid  (Maas)  to  the  food  causes  considerable  thickening  of  the  bones. 
This  seems  to  be  due  to  the  non-absorption  of  those  parts  of  the  bones  which  are 
usually  absorbed,  while  new  growth  is  continually  taking  place.  2.  When  food 
devoid  of  lime  salts  is  given  to  an  animal,  the  growth  of  the  bones  is  not  arrested 
(v.  Voit),  but  the  bones  become  thinner,  whereby  all  parts,  even  the  organic  basis  of 
the  bone,  undergo  a  uniform  diminution  (Chossat,  A.  Milne-Edwards).  3.  Feeding 
with  madder  makes  the  bones  red,  as  the  colouring  matter  is  deposited  with  the 
bone  salts  in  the  bone,  especially  in  the  growing  and  last  formed  parts.  In 
birds,  the  shell  of  the  egg  becomes  coloured.  4.  The  continued  use  of  lactic  acid 
dissolves  the  bones  (Siedamgrotzky  and  Hofmeister).  The  ash  of  bone  is  thereby 
diminished.  If  lime  salts  be  withheld  at  the  same  time,  the  effect  is  greatly 
increased,  so  that  the  bones  come  to  resemble  rachitic  bones.  The  normal  de- 
velopment of  bone  is  described  in  vol.  ii. 

When  a  lost  tissue  is  not  replaced  by  the  same  kind  of  tissue,  its 
place  is  always  taken  by  cicatricial  connective-tissue. 


TRANSPLANTATION   OF  TISSUES.  497 

When  this  ia  tlie  case,  the  part  becomes  inflamed  and  swollen,  owing  to  an 
exudation  of  plasma.  The  blood-vessels  become  dilated  and  congested,  and, 
notwithstanding  the  slower  circulation,  the  amount  of  blood  is  greater.  The 
blood-vessels  are  increased,  owing  to  the  formation  of  new  ones.  Colourless  blood- 
corpuscles  pass  out  of  the  vessels  and  reproduce  themselves,  and  many  of  them 
undergo  fatty  degeneration,  whilst  others  take  up  nutriment  and  become  con- 
verted into  largo  uninucleated  protoplasma-cells,  from  which  giant-cells  are 
developed  (Ziegler,  Cohnheim).  The  newly-formed  blood-vessels  supply  all  these 
elements  with  blood. 

245.  Transplantation  of  Tissues. 

The  nose,  ear,  and  even  a  finger,  after  having  been  severed  from  the  body  by 
a  clean  cut,  have,  under  certain  circumstances,  become  united  to  the  part  from 
which  they  were  removed. 

The  skin  is  freqiiently  transplanted  by  surgeons,  as,  for  example,  to  form  a  new 
nose.  The  piece  of  skin  is  cut  from  the  forehead  or  arm,  to  which  it  is  left 
attached  by  a  bridge  of  skin.  The  skin  is  then  stitched  to  the  part  which  it  is  desired 
to  cover  in,  and  when  it  has  become  attached  in  its  new  situation,  the  bridge  of 
skin  is  severed. 

Reverdin  cut  a  piece  of  skin  into  pieces  about  the  size  of  a  pea  and  fixed  them 
on  an  ulcerated  surface,  where  they,  as  it  were,  took  root,  grew,  and  sent  off  from 
their  margins  epithelial  out-gro\\i;hs,  so  that  ultimately  the  whole  surface  was 
covered  mth  epithelium. 

The  excised  spur  of  a  cock  was  transplanted  and  fixed  in  the  comb  of  the  same 
animal  where  it  grew  (John  Hunter). 

P.  Bert  cut  oif  the  tail  and  legs  of  rats  and  transplanted  them  under  the  skin  of 
the  back  of  other  rats,  where  they  united  with  the  adjoining  parts. 

Oilier  found  that,  when  periosteum  was  transplanted  it  grew  and  reproduced 
bone  in  its  new  situation.  Even  blood  and  lymph  may  be  transfused  {Trails- 
fusion — p.  199). 

All  these  results  seem  only  to  be  possible  between  individuals  of  the  same 
species,  although  Helferich  has  recently  found  that  a  piece  of  a  dog's  muscle,  when 
substituted  for  human  muscle,  united  to  the  adjoining  muscle  and  became 
functionally  active.  [While  J.  R.  Wolfe  has  transplanted  the  conjunctiva  of  the 
rabbit  to  the  human  eye].  Most  tissues,  however,  do  not  admit  of  transplanta- 
tion, e.g.,  glands  and  the  sense-organs.  They  may  be  removed  to  other  parts  of 
the  body,  or  into  the  peritoneal  cavity,  without  exciting  any  inflammatory 
reaction ;  they,  in  fact,  behave  like  inert  foreign  matter. 

246.  Increase  in  Size  and  Weight  during  Growth. 

The  length  of  the  body,  which  at  birth  is  usually  t^  of  the  adult  body,  undergoes 
the  greatest  elongation  at  an  early  period :— in  the  first  year,  20;  in  the  second,  10; 
in  the  third,  about  7  centimetres;  whilst  from  5-16  years  the  annual  increase  is 
about  5 1  centimetres.  In  the  twentieth  year  the  increase  is  very  slight.  From 
50  onwards  the  size  of  the  body  diminishes,  owing  to  the  intervertebral  discs 
becoming  thinner,  and  the  loss  may  be  6-7  centimetres  about  the  eightieth  year. 
The  weight  of  the  body  (^V  of  an  adult)  sinks  during  the  first  5-7  days,  owing  to 
the  evacuation  of  the  meconium  and  the  small  amount  of  food  which  is  taken  at 
first. 

The  increase  of  weight  is  greater  in  the  same  time  than  the  increase  in  length. 
Within  the  first  year  a  child  trebles  its  weight.    The  greatest  weight  is  usually 

32 


498 


INCREASE   IN   SIZE  AND  WEIGHT. 


reached  about  40,  while  towards  60  a  decrease  begins,  which  at  80  may  amount 
even  to  6  kilo.  The  results  of  measurements,  chiefly  by  Quetelet,  are  given  in  the 
following  table: — 


Length  (Cmtr.) 

Weight  (Kilo.) 

Age. 

Length  (Cmtr.) 

Weight  (Kilo.) 

Age. 

Man. 

"Woman. 

Man. 

Woman. 

Man. 

Woman. 

Man. 

Woman. 

0 

49-6 

48-3 

3-20 

2-91 

15 

155-9 

147-5 

46-41 

41-30 

1 

69-6 

69-0 

10-00 

9-30 

16 

161-0 

150-0 

53-39 

44-44 

2 

79-6 

78-0 

12-00 

11-40 

17 

1670 

154-4 

57-40 

49-08 

3 

86 '0 

85-0 

13-21 

12-45 

18 

170-0 

156-2 

61-26 

53-10 

4 

93-2 

91  0 

15-07 

14-18 

19 

170-6 

63-32 

5 

99-0 

97-0 

16-70 

15-50 

20 

171-1 

157-0 

65-00 

54-46 

6 

104-6 

103-2 

18-04 

16-74 

25 

172-2 

157-7 

68-29 

55-08 

7 

111-2 

109-6 

20-16 

18-45 

30 

172  2 

157-9 

68-90 

55-14 

8 

117-0 

113-9 

22-26 

19-82 

40 

171-3 

155-5 

68-81 

56-65 

9 

122-7 

120-0 

24-09 

22-44 

50 

167-4 

153-6 

67-45 

58-45 

10 

128-2 

124-8 

26-12 

24-24 

60 

163-9 

151-6 

65-50 

56-73 

11 

132-7 

127-5 

27-85 

26-25 

70 

162-3 

151-4 

63-03 

53-72 

12 

135-9 

132-7 

31-00 

30-54 

SO 

161-3 

150-6 

61-22 

51-52 

13 

140-3 

138  6 

35-32 

34-65 

90 

57-83 

49-34 

14 

148-7 

1447 

40-50 

38-10 

(Chiefly  from  Quetelet) 

Between  the  12th  and  15th  years,  the  weight  and  size  of  the  female  are  greater 
than  of  the  male.  Growth  is  most  active  in  the  last  months  of  foetal  life,  and 
afterwards  from  the  6th  to  9th  year,  until  the  13th  to  16th.  The  full  stature  is 
reached  about  30,  but  not  the  greatest  weight  (Thoma). 


Greneral  View  of  tlie  Cliemical  Constituents 
of  tlie  Organism. 


247.  (A.)  Inorganic  Constituents. 

I.  Water  forms  58*5  per  cent,  of  the  whole  body,  but  it  occurs  in  different 
quantity  in  the  different  tissues;  the  kidneys  contain  the  most  water,  827  per 
cent.;  bones,  22  per  cent.;  teeth,  10  per  cent.;  while  enamel  contains  the  least, 
0'2  per  cent. 

[  Water  is  of  the  utmost  importance  in  the  economy,  and  it  is  no  paradox  to  say 
that  all  organisms  live  in  water,  for  though  the  entire  animal  may  not  live  in 
water,  all  its  tissues  are  bathed  by  watery  fluids,  and  the  essential  vital  processes 
occur  in  water  (p.  458).  A  constant  stream  of  water  may  be  said  to  be  passing 
through  organisms,  a  certain  quantity  of  water  is  taken  in  with  the  food  and 
drink,  which  ultimately  reaches  the  blood,  while  from  the  blood  a  constant  loss  is 
taking  place  by  the  urine,  the  sweat  and  breath.  The  greater  quantity  of  the  water 
in  our  bodies  is  derived  from  without,  but  it  is  probable  that  a  small  amount  is 
formed  within  our  bodies  by  the  action  of  free  oxygen  on  certain  organic  sub- 
stances. According  to  some  observers,  peroxide  of  hydrogen  (HgOo)  is  also 
present  in  the  body,] 

II.  Gases. — [Oxygen  is  absorbed  from  the  air,  and  enters  the  blood,  where  it 
forms  a  loose  chemical  compound,  with  the  colouring  matter  or  haemoglobin,  while 
a  small  amount  exists  in  a  free  state,  or  is  simply  absorbed.]  Hydrogen  is  found 
in  the  alimentary  canal.  Nitrogen  [like  oxygen,  is  absorbed  from  the  atmosphere 
by  the  blood,  in  which  it  is  dissolved,  and  from  which  it  passes  into  other  fluids 
of  the  body.     It  is  probable  that  a  very  small  quantity  is  formed  within  the  body.] 

The  presence  of  Marsh  gas  (CH4)  (p.  255),  ammonia  (NH3),  and  sulphuretted 
hydrogen  (HoS)  (p.  372)  has  been  referred  to  already. 

III.  Salts. — Sodium  chloride  [is  one  of  the  most  important  inorganic 
substances  present  in  the  body.  It  occurs  in  all  the  tissues  and  fluids 
of  the  body,  and  it  plays  a  most  prominent  part  in  connection  with 
the  diffusion  of  fluids  through  membranes,  and  its  presence  is  necessary 
for  the  solution  of  the  globulins  (p.  502).  In  some  cases  it  exists  in 
a  state  of  combination  with  albuminous  bodies,  as  in  the  blood-plasma. 
Common  salt  is  absolutely  necessary  for  one's  existence;  if  it  be 
withdrawn  entirely,  life  soon  comea  to  an  end.  About  15  grammes 
are  given  off  in  twenty-four  hours,  the  great  part  being  excreted  by 
the  urine.  Boussingault  showed  that,  the  addition  of  a  certain 
amount  of  common  salt  to  the  daily  food  of  cattle  greatly  improved 
their  condition.] 

Calcium  phosphate  [  (CaaPoOg)  is  the  most  abundant  salt  in  the  body,  as  it  forms 
more  than  one-half  of  our  bones,  but  it  also  occurs  in  dentine,  enamel,  and  to  a 


500  SALTS,   ACIDS,   AND  BASES   IN   THE   BODY. 

much  less  extent  in  the  other  solids  and  fluids  of  the  body.  Amongst  secretions, 
milk  contains  relatively  the  largest  amount  (2  "72)  per  cent.  In  milk  it  is  neces- 
sary for  forming  the  calcareous  matter  of  the  bones  of  the  infant.  It  gives  bones 
their  hardness,  solidity,  and  rigidity.  It  is  chiefly  derived  from  the  food,  and  as 
only  a  small  quantity  is  given  off  in  the  excretions,  it  seems  not  to  undergo  rapid 
removal  from  the  body.] 

Sodium  pJiosphate  (PNagO^),  acid  sodium  pliosphate  (PNagHOJ,  acid 
potassium  pJiosphate  (PKJiO^).  [The  sodium  phosphate  and  the 
corresponding  potash  salt  give  most  of  the  fluids  of  the  body  their 
alkaline  reaction.  The  alkaline  reaction  of  the  blood-plasma  is  partly 
due  to  alkaline  phosphates  which  are  chiefly  derived  from  the  food. 
The  acid  sodium  phosphate  is  the  chief  cause  of  the  acid  reaction 
of  the  urine,  A  small  quantity  of  phosphoric  acid  is  formed  in  the 
body  owing  to  the  oxidation  of  "  lecithin  "  which  contains  phosphorus, 
and  also  forms  an  important  constituent  of  nerve-tissue.] 

Sodium  carbonate  (Na2C03)  and  sodium  bicarbonate  (NaHCOs)  [exist  in  small 
quantities  in  the  food,  and  are  chiefly  formed  in  the  body  from  the  decomposition 
of  the  salts  of  the  vegetable  acids.  They  occur  in  the  blood-plasma,  where  they 
play  an  important  part  in  carrying  the  CO2  from  the  tissues  to  the  lungs.] 

Sodium  and  potassium  sulphates  (]S"aS04,  and  K2SO4)  [exist  in  very  small 
quantity  in  the  body,  and  are  introduced  with  the  food,  but  part  is  formed  in  the 
body  from  the  oxidation  of  organic  bodies  containing  sulphur.] 

[Potassium  chloride  (KCI2)  is  pretty  widely  distributed,  and  it  occurs  specially 
in  muscle,  coloured  blood-corpuscles,  and  milk.  Calcium  fluoride  (CaFl2)  occurs 
in  small  quantity  in  bones  and  teeth.  Calcium  carbonate  (CaOOa)  is  associated 
with  calcium  phosphate  in  bone,  tooth,  and  in  some  fluids,  but  it  occurs  in  rela- 
tively much  smaller  amount.  It  is  kept  in  solution  by  alkaline  chlorides,  or  by  the 
presence  of  free  carbonic  acid.] 

Ammonium  chloride  (NH4CI). — [Minute  traces  occur  in  the  gastric  juice  and 
the  urine.] 

Magnesium  phosphate  (Mg3P04)  [occurs  in  the  tissues  and  fluids  of  the  body 
along  with  calcium  phosphate,  but  in  very  much  smaller  quantity.] 

IV.  FreeAcids. — Hydrochloric  acid  (HCl)  [occurs  free  in  the  gastric  juice,  but 
in  combination  with  the  alkalies  it  is  widely  distributed  as  chlorides.]  Sulphuric 
acid  (H2SO4)  [is  said  to  occur  free]  in]  the  saliva  of  certain  gasteropods,  as  Dolium 
galea.  In  the  body  it  forms  sulphates,  being  chiefly  in  combination  with  soda  and 
potash.] 

V.  Bases* — Silicon  as  silicic  acid  (Si02);  manganese,  iron,  the  last  forms  an 
integral  constituent  of  the  blood  pigment ;  copper  (?),  p.  352. 

248.  (B.)  Organic  Compounds. 

I.  The  Albuminous  or  Proteid  Substances. 
1.  Froteids  and  their  Allies. 

Proteids  and  their  allies  are  composed  of  C,  H,  0,  N,  and  S,  and  are  derived 
from  plants  (see  Introduction), 
[According  to  Hoppe-Seyler  their  general  percentage  composition  is 

0.  B.  N.  C.  S. 

From  .    .     .     20-9        6-9       15-2        51-5        0*3 
to  ...     .     23-5  to  7-3  to  17-0  to  54'5  to  2-0.] 


CHARACTERS   OF  THE   PROTEIDS.  501 

They  exist  in  all  animal  fluids,  and  in  nearly  all  the  tissues.  They  occur  partly 
in  the  fluid  form,  although  Briicke  maintains  that  the  molecule  of  albumin  exists 
in  a  condition  midway  between  a  state  of  imbibition  and  a  true  solution— and 
partly  in  a  more  concentrated  condition. 

Besides  forming  the  chief  part  of  muscle,  nerve,  and  gland,  they  occur  in  nearly 
all  the  fluids  of  the  body,  including  the  blood,  lymph,  and  serous  fluids,  but  in 
health  mere  traces  occur  in  the  sweat,  while  they  are  absent  from  the  bile  and  the 
urine.  White  of  egg  is  the  type.  In  the  alimentary  canal  they  are  changed  into 
peptones.  The  cliief  products  derived  from  their  oxidation  within  the  body  are 
CO2H3O,  and  especially  urea,  which  contauis  nearly  all  the  N  of  the  proteids. 

Coustitation. — Their  chemical  constitution  is  quite  unknown.  The  N  seems 
to  exist  in  two  distinct  conditions,  partly  loosely  combined,  so  as  to  yield  am- 
monia readily  when  they  are  decomposed,  and  partly  in  a  more  fixed  condition. 
According  to  Pfliiger,  part  of  the  N  in  living  proteid  bodies  exists  in  the  form  of 
cyanogen.  The  proteids  form  a  large  group  of  closely  related  substances,  all  of 
which  are  perhaps  modifications  of  the  same  body.  When  we  remember  that 
the  infant  manufactures  most  of  the  proteids  of  its  ever-growing  body  from  the 
casein  of  milk,  this  last  view  seems  not  improbable. 

Characters. — Proteids,  the  anhydrides  of  peptones  are  colloids  (p.  394),  and 
therefore  do  not  diffuse  easily  through  animal  membranes ;  they  are  amorphous 
and  do  not  crystallise,  and  hence  are  isolated  with  difficulty  ;  some  are  soluble  and 
others  are  insoluble  in  water ;  they  are  insoluble  in  alcohol ;  they  rotate  the  ray  of 
polarised  light  to  the  left;  in  a  flame,  they  give  the  odour  of  burned  horn. 
Various  metallic  salts  and  alcohol  precipitate  them  from  their  solution,  and  they 
are  coagulated  by  heat,  mineral  acids  and  the  prolonged  action  of  alcohol.  Caustic 
alkalies  dissolve  them  (yellow),  and  from  this  solution  they  are  precipitated  by  acids. 

Decompositions. — When  acted  upon  in  a  suitable  manner  by  acids  and  alkalies, 
they  give  rise  to  the  decomposition  products— leucin  (10-18  per  cent.),  tyrosin 
(0'25-2  per  cent.),  asparaginic  acid,  glutamic  acid,  and  also  volatile  fatty  acids, 
benzoic  and  hydrocyanic  acids,  and  aldehydes  of  benzoic  and  fatty  acida ;  also, 
indol  (Hlasiwetz,  Habermann).  Similar  products  are  formed  during  pancreatic 
digestion  (p.  342),  and  during  putrefaction  (p.  376). 

Reactions, — They  are  coagulated  by  (1)  nitric  acid,  and  when  boiled  there- 
with give  a  yellow,  the  xanthoproteic  reaction;  the  addition  of  ammonia  gives  a 
deep  orange  colour. 

(2)  Millon's  reagent  (nitrate  of  mercury  with  nitrous  acid);  when  heated  with 
this  reagent  above  GO^C,  they  give  a  red,  probably  owing  to  the  formation  of 
tyrosin.  [If  the  proteids  are  present  in  large  amount,  a  red  precipitate  occurs, 
but  if  mere  traces  are  present  only  the  fluid  becomes  red.] 

(3)  The  addition  of  a  few  drops  of  solution  of  cupric  sulphate,  and  the  subse- 
quent addition  of  caustic  potash  or  soda  give  a  violet  colour,  which  deepens  on 
boiling,  [or  the  same  colour  may  be  obtained  by  adding  a  few  drops  of  Fehling'a 
solution.  ] 

(4)  They  are  precipitated  by  acetic  acid  and  potassium  ferrocyanide. 

(5)  WThen  boiled  with  concentrated  hydrochloric  acid  they  give  a  violet-red 
colour. 

(6)  Sulphuric  acid  containing  molybdic  acid  gives  a  blue  colour  (Frohde). 

(7)  Their  solution  in  acetic  acid  is  coloured  violet  with  concentrated  sulphuric 
acid,  and  shows  the  absorption -band  of  hydrobilirubin  (Adamkiewicz). 

(8)  Iodine  is  a  good  microscopic  reagent,  which  strikes  a  brownish-yellow,  while 
sulphuric  acid  and  cane-sugar  give  a  purplish-violet  (E.  Schultze). 

[  (9)  When  boiled  with  acetic  acid  and  an  equal  volume  of  a  concentrated 
solution  of  sodium  sulphate,  they  are  precipitated.  This  method  is  frequently 
used  for  removing  proteids  from  other  liquids,  as  it  does  not  interfere  with  the 
presence  of  other  substances.] 


602  NATIVE  ALBUMINS   AND   GLOBULINS, 

249,  The  Animal  Proteids  and  their  Characters. 

They  have  been  divided  into  classes: — 

Class  I. — Native  Albumins. 

Native  Albumins  occur  in  a  natural  condition  in  the  solids  and  fluids  of  the 
body.  They  are  soluble  in  water,  and  are  not  precipitated  by  alkaline  carbonates, 
NaCl,  or  by  very  dilute  acids.  Their  solutions  are  coagulated  by  heat  at  65^-73°C. 
Dried  at  40''C.,  they  yield  a  clear  yellow  amber-coloured  friable  mass,  "  soluble 
albumin,'"  which  is  soluble  in  water. 

(1.)  Serum-albumin,  whose  chemico-physical  characters  are  given  at  p.  49, 
and  its  physiological  properties  at  §  41.  Almost  all  its  salts  may  be  removed 
from  it  by  dialysis,  when  it  no  longer  coagulates  with  heat  (Schmidt).  It  is 
coagulated  by  strong  alcohol,  and  is  easily  dissolved  in  strong  hydrochloric  acid. 
When  precipitated,  it  is  readily  soluble  in  strong  nitric  acid.  It  is  not  coagulated 
when  shaken  up  with  ether.  The  addition  of  water  to  the  hydrochloric  solution 
precipitates  acid-albumin. 

(2.)  Egg-albumin. — When  injected  into  the  blood-vessels  or  under  the  skin,  or 
even  when  introduced  in  large  quantity  into  the  intestine,  part  of  it  appears 
unchanged  in  the  urine  (p.  397).  When  shaken  with  ether,  it  is  precipitated. 
These  two  reactions  serve  to  distinguish  it  from  (1).  The  specific  rotation  is — 
37-8°, 

(Metalbumin  and  Paralbumin  have  been  found  by  Scherer  in  ropy 
solutions  in  ovarian  cysts;  they  are  only  partially  precipitated  by  heat.  The 
precipitate  thrown  down  by  the  action  of  strong  alcohol  is  soluble  in  water. 
They  are  not  precipitated  by  acetic  acid,  by  acetic  acid  and  potassium  ferro- 
cyanide,  by  mercuric  chloride,  or  by  saturation  with  magnesium  sulphate.  Con- 
centrated sulphuric  acid  and  acetic  acid  give  a  violet  colour  (Adamkiewicz). 
According  to  Hammarsten,  metalbumin  is  a  mixture  of  paralbumin  and  other 
proteid  substances.  On  being  boiled  with  dilute  sulphuric  acid  they  yield  a 
reducing  substance  (?  sugar)). 

Class  II. — Globulins. 

They  are  native  proteids,  which  are  insoluble  in  distilled  water,  but  are  soluble 
in  dilute  saline  solutions,  sodium  chloride  of  1  per  cent.,  and  in  magnesium  sulphate. 
These  solutions  are  coagulated  by  heat,  and  are  precipitated  by  the  addition  of  a 
large  quantity  of  water.  Most  of  them  are  precipitated  from  their  sodium  chloride 
solution  by  the  addition  of  crystals  of  sodium  chloride,  and  also  by  saturating 
their  neutral  solution  at  30°  with  crystals  of  magnesium  sulphate.  When  acted 
upon  by  dilute  acids,  they  yield  acid-albumin,  and  by  dilute  alkalies,  alkali- 
albumin. 

(1.)  Globulin  (Crystallin)  is  obtained  by  passing  a  stream  of  COg  through  a 
watery  extract  of  the  crystalline  lens. 

(2.)  Vitellin  is  the  chief  proteid  in  the  yolk  of  egg.  It  is  also  said  to  occur 
in  the  chyle  (?)  and  in  the  amniotic  fluid  (Weyl),  Both  of  the  foregoing  are  not 
precipitated  from  their  neutral  solutions  by  saturation  with  sodium  chloride. 

(3.)  Para-globulin  or  Serum-globulin  (p.  44). 

(4.)  Fibrinogen  (p.  45). 

(5.)  Myosin  is  the  chief  proteid  in  dead  muscle.  Its  coagulation  in  muscle 
post  mortem  constitutes  rigor  mortis.  If  muscle  be  repeatedly  washed  and  after- 
wards treated  with  a  10  per  cent,  solution  of  sodium  chloride,  it  yields  a  viscid 
fluid  which,  when  dropped  into  a  large  quantity  of  distilled  water,  gives  a  white 
flocculent  precipitate  of  myosin.  It  is  also  precipitated  from  its  NaCl  solution 
by  crystals  of  NaCl.     For  Kiihne's  method  of  preparation,  see  Muscle. 

(6.)  Globin  (Preyer),  the  proteid  residue  of  hasmoglobin. 


ALBUMINATES  AND   OTHER  PROTEIDS.  503 

Class  III. — Derived  Albumins  (Albuminates). 

(1.)  Acid- Albumin  or  Syntonin.— "V^Tien  proteids  are  dissolved  in  the  stronger 
acids,  e.g.,  hydrochloric,  they  become  changed  into  acid-albumins.  They  are 
precipitated  from  solution  by  the  addition  of  many  salts  (NaCl,  Na2S04)  or  by 
neutralisation  with  an  alkali,  e.g.,  sodic  carbonate,  but  they  are  not  precipitated 
by  heat.  The  concentrated  solution  gelatinises  in  the  cold,  and  is  redissolved  by 
heat.  Sijntonin,  which  is  obtained  by  the  prolonged  action  of  dilute  hydrochloric 
acid  (2  per  1000)  upon  minced  muscle,  is  also  an  acid-albumin.  It  is  formed  also 
in  the  stomach  during  digestion.  According  to  Soyka,  the  alkali-  and  acid- 
albumins  differ  from  each  other  only  in  so  far  as  the  proteid  in  the  one  case  is 
united  with  the  base  (metal)  and  in  the  other  with  the  acid. 

(2.)  Alkali- Albumin. — If  egg-  or  serum-albumin  be  acted  upon  by  dilute 
alkalies,  a  solution  of  alkali-albumin  is  obtained.  Strong  caustic  potash  acts  upon 
white  of  egg  and  yields  a  thick  jelly  (Lieberkiihn).  The  solution  is  not  precipitated 
by  heat,  but  is  precipitated  by  the  addition  of  an  acid. 

(3. )  Casein  is  the  chief  proteid  in  milk  (p.  466).  It  is  precipitated  by  acids  and  by 
rennet  at  40°C.  In  its  characters  it  is  closely  related  to  alkali-albuminate,  but, 
according  to  O.  Nasse,  it  contains  more  ^N".  It  contains  a  large  amount  of  phos- 
phorus (0'83  per  cent.).  It  may  be  precipitated  from  milk  by  diluting  it  with 
several  times  its  volume  of  water  and  adding  dilute  acetic  acid,  or  by  adding 
magnesium  sulphate  crystals  to  milk  and  shaking  vigorously.  Owing  to  the  large 
amount  of  phosphorus  which  it  contains,  it  is  sometimes  referred  to  the  nucleo- 
albumins.  When  it  is  digested  with  dilute  HCl  (0*1  per  cent.)  and  pepsin  at  the 
temperature  of  the  body,  it  gradually  yields  nuclein. 

Class  IV.— Fibrin. 
For  fibrin,  see  p.  39,  and  for  the  fibrin-factors,  p.  43. 

Class  v. — Peptones. 

For  peptones  and  propeptones,  see  p.  331. 

Class  VI. — Lardacein  and  Other  Bodies. 

There  fall  to  be  mentioned  the  "yelk-plates,"  which  occur  in  the  yelk: — 
Ichthin  (cartilaginous  fishes,  frog) ;  Ichthidin  (osseous  fishes) ;  Ichthulin  (salmon) ; 
Emydin  (tortoise— Valenciennes  and  Fremy);  also  the  indigestible  Amyloid  stibstance 
(Virchow)  or  lardacein,  which  occurs  chiefly  as  a  pathological  infiltration  into  various 
organs,  as  the  liver,  spleen,  kidneys,  and  blood-vessels.  It  gives  a  blue  with  iodine 
and  sulphuric  acid  (like  cellulose),  and  a  mahogany-brown  with  iodine.  It  is 
difficult  to  change  it  into  an  albuminate  by  the  action  of  acids  and  alkalies. 

Class  VII. — Coagulated  Proteids. 

When  any  native  albumins  or  globulins  are  coagulated,  e.g.,  at  70°C. ,  they  yield 
bodies  with  altered  characters,  insoluble  in  water  and  saline  solutions,  but  soluble 
in  boiling  strong  acids  and  alkalies,  when  they  are  apt  to  split  up.  They  are 
dissolved  during  gastric  and  pancreatic  digestion  to  produce  peptones. 

Appendix:  Vegetable  Proteid  Bodies. 

Plants,  like  animals,  contain  proteid  bodies,  although  in  less  amount.  They 
occur  either  in  solution  in  the  juices  of  living  plants  or  in  the  solid  form.  In  com- 
position and  reaction  they  resemble  animal  proteids.  Vegetable  proteids  have  fre- 
quently been  obtained  in  a  crystalline  form  (Eadlkofer),  e.g.,  from  the  seeds  of 
the  gourd  (Griibler)  and  various  oleaginous  seeds  (Ritthausen). 


504  VEGETAELE    PEOTEIDS. 

1.  Vegetable  albnmill  is  found  dissolved  in  most  juices  of  plants  and  closely 
resembles  animal  albumin.  If  tlie  dongli  of  "wheat  be  washed  with  water,  and  the 
starch  be  allowed  to  subside,  on  boiling  the  supernatant  fluid  the  vegetable 
albumin  is  coagulated. 

2.  Glutin  (vegetable  fibrin)  occurs  iu  cereal  grains,  and  its  peculiar  glutinous 
or  sticky  characters,  when  mixed  with  water,  enable  it  to  form  dough.  From 
wheat,  which  may  contain  as  much  as  17  per  cent.,  it  is  prepared  by  washing  away 
all  the  starch  from  the  dough  with  a  stream  of  water.  This  is  best  effected  by 
washing  the  dough  in  a  musHn  bag  or  over  a  fine  sieve.  It  is  elastic,  gray,  insol- 
uble in  water  and  alcohol,  and  soluble  in  dilute  acids  (1  HQ  per  1000),  and  in 
alkalies.  Glutin  is  a  complex  substance.  If  it  be  boiled  with  water  a  sticky 
varnish-like  mass  is  obtained,  gliadin  (animal  gelatin).  If  this  substance  is 
treated  with  strong  alcohol  it  dissolves,  but  a  slimy  body  remains  undissolved, 
mucedin.  If  glutin  be  digested  with  alcohol,  a  brownish-yellow  substance,  glutin- 
jwrin  (Pdtthausen)  is  extracted  from  it. 

3.  Vegetable  casein,  occurs  specially  iu  the  leguminosae.  It  is  slightly  soluble 
in  water,  b::t  readily  soluble  iu  weak  alkalies,  and  in  solutions  of  basic  calcic 
phosphate.  These  solutions,  Kke  animal  casein,  are  precipitated  by  acids  or 
rennet.  The  varieties  of  it  are— (a)  Leguminin^as,  beans,  lentils  (Einhof,  1805); 
it  has  an  acid  reaction,  is  insoluble  in  water,  easily  soluble  in  dilute  alkalies,  and 
iu  very  dilute  HCl  or  acetic  acid;  (V)  the  casein-like  bod}'  occurring  in  hops  and 
almonds  which  closely  resembles  (a),  and  is  called  conglvAin  (Eitthausen).  Vegetable 
casein,  like  animal  c-asein,  is  an  alkali-albuminate,  and  is  precipitated  by  the  same 
substances ;  it  is  not  precipitated  by  boiling.  When  long  exposed  to  the  air,  its 
solution  coagulates  with  the  formation  of  lactic  acid. 

250.  (2.)  TtLe  Albuminoids. 

These  substances  closely  resemble  true  proteids  iu  their  composition  and  origin, 
and  are  amorphous  non-crystalline  colloids;  some  of  them  do  not  contain  S,  but 
the  most  of  them  have  not  been  prepared  free  from  ash.  Their  reactions  and 
decomposition  products  closely  resemble  those  of  the  proteids ;  some  of  them  pro- 
duce, in  addition  to  leuciu  and  tyrosin,  ghjcin  and  oJanin  (amido-propionic  acid). 
They  occur  as  orgainised  constituents  of  the  tissues  and  also  iu  a  fluid  form.  It  is 
unknown  whether  they  are  formed  by  oxidation  from  proteid  bodies  or  by 
synthesis. 

1 .  Uncin  is  the  characteristic  substance  present  in  mucus.  It  contains  no  S. 
That  obtained  from  the  sub-maxillary  gland  contains  C.  52'31,  H.  7'22,  ^s".  11  "84, 
0.  28 '63  (Obolensky).  It  dissolves  iu  water,  making  it  sticky  or  slimy,  and  can  be 
filtered.  It  is  precipitated  by  acetic  acid  and  alcohol ;  and  the  alcohol  precipitate 
is  again  soluble  iu  water.  It  is  not  precipitated  by  acetic  acid  and  ferro -cyanide  of 
potassium,  but  HZsOs  and  other  mineral  acids  precipitate  it  (Scherer).  It  occurs 
in  saliva  (jj.  292),  in  bile,  in  mucous  glands,  secretions  of  mucous  membranes,  in 
mucous  tissue,  in  syno^na,  and  in  tendons  (A.  RoUet).  Pathologically  it  occurs 
not  unfrequently  in  cysts ;  iu  the  animal  kingdom,  especially  iu  snails  and  in  the 
skin  of  holothurians  (Eichwald).  It  yields  leuctn  and  7  per  cent,  of  tyrosin  when 
it  is  decomposed  by  prolonged  boiling  with  sulphuric  acid. 

2.  Nttclein  (Miescher— p.  409)  C.  29,  H.  49,  N.  9,  P.  3,  0.  22,  is  sHghtly 
soluble  in  water,  easily  in  ammonia,  alkaline  carbonates,  strong  HUSTOs ;  it  gives 
the  biuret-reaction ;  no  reaction  with  IMillon's  reagent ;  when  decomposed  it  yields 
phosphorus.  It  occurs  in  the  nuclei  of  pus  and  blood-corpuscles  (p.  36),  in 
spermatozoids,  yelk-spheres,  liver,  brain,  and  milk,  yeast,  fungi,  and  many  seeds. 
Its  most  remarkable  characteristic  is  the  large  quantity  of  jjhosphorus  it  contains, 
nearly  10  per  cent.  Hypoxaathin  and  guanin  have  been  obtained  as  decomposition 
products  from  it  (Kossel), 


THE  ALBUMINOIDS. 


505 


3.  Keratin  occurs  in  all  horny  and  epidermic  tissues  (epidermic  scales,  hairs, 
nails,  feathers)-  C.  50-3-52-5  ;  H.  G-4-7 ;  N.  16-2-17-7  ;  O.  20-8-25  ;  S.  0-7-5  per 
cent.,  is  soluble  only  in  boiling  caustic  alkalies, but  swells  up  in  cold  concentrated 
acetic  acid.  When  decomposed  by  H2SO4  it  yields  10  per  cent,  leucin  and  3-6  per 
cent,  tyrosin. 

4.  Fibroin  is  soluble  in  strong  alkalies  and  mineral  acids,  in  ammonio- 
sulphate  of  copper ;  when  boiled  with  H2SO4  it  yields  5  per  cent,  tyrosin,  leucin, 
and  glycin.  It  is  the  chief  constituent  of  the  cocoons  of  insects  and  threads  of 
spiders. 

5.  Spongin,  allied  to  fibroin,  occurs  in  the  bath-sponge,  and  yields  as  decom- 
position products,  leucin  and  glycin  (Stiideler). 

6.  Elastin,  the  fundamental  substance  in  elastic  tissue,  is  soluble  only 
when  boiled  in  concentrated  caustic  potash  (C.  55-55-6  ;  H.  7-1-7 "7  ;  N.  16-1-17-7; 
0.  19-2-21  -1  per  cent. )   It  yields  36^5  per  cent,  of  leucin  and  ^  per  cent,  of  tyrosin. 

7.  Gelatin,  obtained  from  connective-tissues  by  prolonged  boiling  with 
water;  it  gelatinises  in  the  cold  (C.  522-50-7;  H.  6*6-7-2;  N.  17-9-lS'8; 
S.  -f  0,  23-5-25  ;  (S.  0-6  per  cent.).  [The  ordinary  connective-tissues  are  supposed 
to  contain  the  hypothetical  anhydride  collagen,  while  the  organic  basis  of  bone  is 
called  ossein.'^  It  rotates  the  ray  of  polarised  light  strongly  to  the  left.  By  pro- 
longed boiling  and  digestion  it  is  converted  into  a  peptone-hke  body  (gelatin- 
peptone),  which  does  not  gelatinise  (p.  332).  [It  swells  up,  but  does  not  dis- 
solve in  cold  water  ;  when  dissolved  in  warm  water  and  tmged  with  Berlin  blue 
or  carmine  it  forms  the  usual  coloured  mass  which  is  employed  by  histolocrists  for 
making  fine  transparent  injections  of  blood-vessels.]  A  body  resembling  gelatin 
is  found  in  leuksemic  blood  and  in  the  juice  of  the  spleen  (p.  206).  When  decom- 
posed with  sulphuric  acid  it  yields  glycin,  ammonia,  leucin,  but  no  tyrosin.  It 
gives  insoluble  precipitates  with  mercuric  chloride  and  tannin. 

8.  Chondrin  (Joh.  Mllller)  occurs  in  the  matrix  of  hyaline  cartilage  and  between 
the  fibres  in  fibro-cartilage.  It  is  obtained  from  hyaline  cartilage  and  the  cornea 
by  boiling.  It  occurs  also  in  the  mantle  of  molluscs  (C.  49-5-50-9  ;  H.  6  6-7-1 ; 
N.  14-4-14-9;  S  +  0.  27-2-29;  S.  0-4  per  cent.).  When  boiled  with  sulphuric 
acid  it  yields  leucin;  with  hydrochloric  acid,  and  when  digested  chondro-glucose 
(Meissner);  it  belongs  to  the  glucosides,  which  contain  N.  When  acted  upon  by 
oxidising  reagents  it  is  converted  into  gelatin  (Brame).  The  substance  which 
yields  chondrin  is  called  chondrogen,  which  is  perhaps  an  anhydride  of  chondrin. 
The  following  properties  of  gelatin  and  chondrin  are  to  be  noted : 


Reagent. 

Gelatin. 

Chondrin. 

Acids,      .... 

Not  precipitated,    . 

Precipitated     by     acetic 
acid,    dilute  HCl   and 
H2SO4. 

Tannic     acid,    mercuric 

chloride, 

Precipitated,  . 

Give  slight  opalescence. 

Chlorine  water,   x)latinic 

chloride. 

Precipitated. 

Alum,  silver,  iron,  cop- 

per, lead  salts, 

Precipitated,  . 

Precipitated  copiously. 

Potassic  ferrocyanide  and 

acetic  acid. 

Not  precipitated. 

Alcohol, 

Precipitated,   precipitate 
soluble  in  water. 

Specific  Rotation,   .        , 

-130°. 

—213°. 

506 


HYDROLYTIC   FERMENTS. 


9.  The  hydrolytic  ferments  Have  recently  been  called  Enzymes  by  W. 

Kiilme,  in  order  to  distinguish,  them  from  organised  ferments,  such  as  yeast.  The 
enzymes,  hydroljrfcic  or  organic  ferments,  act  only  in  the  presence  of  water.  They 
act  upon  certain  bodies  causing  them  to  take  up  a  molecule  of  water.  They  all 
decompose  hydric  peroxide  into  water  and  O.  They  are  most  active  between  30- 
35°C.,  and  are  destroyed  by  boiling,  but  when  dry  they  may  be  subjected  to  a 
temperature  of  100°  without  being  destroyed.  Their  solutions,  if  kept  for  a  long 
time,  gradually  lose  their  properties  and  undergo  more  or  less  decomposition. 

[Table    showing    the    unorganised    ferments   present  in  the  body,   and  their 
actions: — 


Fluid  or  Tissues. 


Ferment. 


Actions. 


Saliva, 


1,  Ptyalin,    .     . 
(See  also  p.  296.) 


Converts  Starch  chiefly  into  Maltose. 


Gastric  Juice, 


Pancreatic 
Juice,     . 


Intestinal 
Juice, 


Blood,  .  . 
Chyle,  .  . 
Liver,       .     . 

Milk,  .  .  . 
Most  Tissues, 


1.  Pepsin,    .     .     . 

2.  Milk-curdling, 

3.  Lactic  Acid  Ferment 

4.  Eat-splitting,     .     -j 


Converts  Proteids  into  Peptones  in  an 
Acid  Medium,  certain  by-products 
being  formed  (p.  331). 

Curdles  Casein  of  Milk. 

Splits  up  Milk-sugar  into  Lactic  Acid. 

Splits  up  Fats  into  Glycerin  and 
Fatty  Acids. 


1.  Diastatic  or 

Amylopsin,     . 

2.  Trypsin,  .     .     . 

3.  Emulsive,     .     . 

4.  Fat-splitting  or 

Steapsin,     .     . 

5.  Milk-curdling,  . 


{ 


Converts  Starch  chiefly  into  Maltose. 

Changes  Proteids  into  Peptones  in 
an  Alkaline  Medium,  certain  by- 
products being  formed  (p.  341). 

Emulsifies  Fats. 

Splits  Fats  into  Glycerin  and  Fatty 
Acids. 

Curdles  Casein  of  Milk. 


1.  Diastatic, 

2.  Proteolytic,  . 

3.  Invertin, 

4.  Milk-curdling, 


Does  not  form  Maltose,  but  Maltose  is 

changed  into  Glucose  (p.  370). 
Fibrin  into  Peptone  (?). 
Changes  Cane-  into  Grape-Sugar. 
(?in  Small  Intestine.) 


Diastatic  Ferments. 


Muscle, 
Urine, 


j-  Pepsii 


Blood 


■   •  { 


Fibrin-forming 
Ferment. 


(Modified  from  W,  Roberts).] 


ORGANISED    AND   UNORGANISED   FERMENTS.  507 

(a.)  Sugar-forming  or  diastatic  ferment  occurs  in  saliva  (p,  294),  pancreatic  juice 
(p.  340),  intestinal  juice  (p.  335),  bile  (p.  366),  blood  (p.  36),  chyle  (p.  410), 
liver  (p.  351),  in  human  milk  (p.  465).  Invertin  in  intestinal  juice  (p.  370). — 
(CI.  Bernard.) 

Almost  all  dead  tissues,  organic  fluids,  and  even  proteids,  although  only  to  a 
slight  degree,  may  act  diastatically.  Diastatic  ferments  are  very  generally  distri- 
buted in  the  vegetable  kingdom. 

(b.)  Proteohjtic  or  Ferments  which  act  upon  proteids. — Pepsin  in  gastric  juice 
and  in  muscle  (p.  332),  in  vetches,  myxomycetes  (Krukenberg),  trypsin  in  the 
pancreatic  juice  (p.  341),  and  a  similar  ferment  in  the  intestinal  juice  (p.  370). 

(c.)  Fat-decomposing  in  pancreatic  juice  (p.  343)  in  the  stomach  (p.  335). 

(d.)  Milk-coagidating  in  the  stomach  (p.  335),  pancreatic  jiiice  (p.  344),  and 
perhaps  also  in  the  intestinal  juice  (?) — W.  Roberts. 

[The  importance  of  fermentative  processes  has  already  been  referred  to  in  detail 
under  "  Digestion."  Ferments  are  bodies  which  excite  chemical  changes  in  other 
matter  with  which  they  are  brought  into  contact.  They  are  divided  into  two 
classes  :— 

(1.)   Unorganised,  soluble  or  non-living. 
(2.)  Organised,  or  living. 

(1.)  The  Unorganised  ferments  are  those  mentioned  in  the  above  table.  They 
seem  to  be  nitrogenous  bodies,  although  their  exact  composition  is  unknown,  and 
it  is  doubtful  if  they  have  ever  been  obtained  perfectly  pure.  They  are 
2yroduced  within  the  body,  in  many  secretions,  by  the  vital  activity  of  the 
protoplasm  of  cells.  They  are  termed  soluble  because  they  are  soluble  in  water, 
glycerine,  and  some  other  substances  (p.  295),  while  they  can  be  precipitated  by 
alcohol  and  some  other  reagents.  They  do  not  multiply  during  their  activity,  nor 
is  their  activity  prevented  by  a  certain  proportion  of  salicylic  acid.  They  are 
not  affected  by  oxygen  subjected  to  the  compression  of  many  atmospheres 
(P.  Bert).     They  are  non-living.     Their  other  properties  are  referred  to  above]. 

[(2.)  The  Organised  or  living  ferments  are  represented  by  yeast  (p.  474).  Other 
living  ferments  belonging  to  the  schizomycetes,  occurring  in  the  intestinal  canal, 
are  referred  to  in  §  184.  Yeast  causes  fermentation  by  splitting  up  sugar  into  COj 
and  alcohol  (p.  298),  but  this  result  only  occurs  so  long  as  the  yeast  is  living. 
Hence,  its  activity  is  coupled  vrith  the  vitality  of  the  cells  of  the  yeast.  If  yeast 
be  boiled,  or  if  it  be  mixed  with  carbolic  or  salicylic  acid,  or  chloroform,  all  of 
which  destroy  its  activity,  it  cannot  produce  the  alcoholic  fermentation.  As  yet 
no  one  has  succeeded  in  extracting  from  yeast  a  substance  which  will  excite  the 
alcoholic  fermentation.  All  the  organised  ferments  grow  and  multiply  during 
their  activity  at  the  expense  of  the  substances  in  which  they  occur.  Thus  the 
alcoholic  fermentation  depends  upon  the  "  life"  of  the  yeast.  They  are  said  to  be 
killed  by  oxygen  subjected  to  the  compression  of  many  atmospheres  (P.  Bert). 
But  it  is  important  to  note  that  Hoppe-Seyler  has  extracted  from  dead  yeast 
(killed  by  ether),  an  unorganised  ferment  which  can  change  cane-sugar  into  grape- 
sugar. 

All  purely  physiological  processes  in  the  body,  except  some  in  the  intestinal 
canal,  depend  upon  unorganised  ferments]. 

10.  HaBmOglobin,  the  colouring  matter  of  blood,  which,  in  addition  to 
C,H,0,N,  andS,  contains  iron,  may  be  taken  with  the  albuminoids  (p.  23). 


508  GLUCOSIDES,   AND   ORGANIC   ACIDS. 


(3.)  Grlucosides  containing  Nitrogen. 

In  addition  to  chondrin,  tlie  f ollo'wing  glucosides  containing  nitrogen,  when  sub- 
jected to  hj'drolytic  processes,  may  combine  with  water,  and  form  sugar  and  other 
substances: — 

Cerebrin  (see  Nervous  System)  =  C5'jB.ii(,'N2026  (Geoghegan). 

Protagon  occurs  in  nerves,  and  contains  phosphorus. 

Chitin,  2(Ci5H26N20io),  is  a  glucoside  containing  nitrogen,  and  occurs  in  the 
cutaneous  coverings  of  arthropoda,  and  also  in  their  intestine  and  tracheae;  it  is 
soluble  in  concentrated  acids,  e.g.,  hydrochloric  or  nitric  acid,  but  insoluble  in 
other  reagents.  According  to  Sandwick,  chitin  is  an  amin- derivative  of  a  carbo- 
hydrate with  the  general  formula  n(Ci2H2oOio).  The  hyalin  of  worms  is  closely 
related  to  chitin.  (Solanin,  amygdalin,  p.  49,  and  salicin,  &c.j  are  glucosides  of 
the  vegetable  kingdom. ) 

(4.)  Colouring  Matters  containing  Nitrogen. 

Their  constitution  is  unknown,  and  they  occur  only  in  animals.  They  are  in 
all  probability  derivatives  of  haemoglobin.  They  are — (1)  hcematin  (p.  33)  and 
hcematoidin  (p.  33).  (2)  Bile-pigments  (p.  357).  (3)  Urine-pigments  (except 
Indican).  (4)  Melanin,  C.  44-2,  H3,  N.  9*9,  0.  42-6,  or  the  black  pigment,  which 
occurs  partly  in  epithelium  (choroid,  retina,  iris,  and  in  the  deep  layers  of 
epidermis  in  coloured  races)  and  partly  in  connective-tissue  corpuscles  (Lamina 
fusca  of  the  choroid). 

II.— Organic  Acids  free  from  Nitrogen. 

(1.)  The  fatty  acids  with  the  formula  CnH2n-iO(OH)  occur  in  the  body 
partly  free  and  partly  in  combination.  Free  volatile  fatty  acids  occur  in  decom- 
posing cutaneous  secretions  (sweat).  In  combination,  acetic  acid  and  caproic  acid 
occur  as  amido-compounds  in  glycin  (  =  amido-acetic  acid),  and  leucin  ( =  amido- 
caproic  acid).  More  especially  do  they  occur  united  with  glycerine  to  form  neutral 
fats,  from  which  the  fatty  acid  is  again  set  free  by  pancreatic  digestion  (p.  343). 

(2.)  The  acids  of  the  acrylic  acid  series,  with  the  formula  CnH2n-30(HO),  are 
represented  in  the  body  by  one  acid,  oleic  acid,  which  in  combination  with 
glycerine  yields  the  neutral  fat  olein. 

251.  Fats. 

Fats  occur  very  abundantly  in  animals,  but  they  also  occur  in  all  plants;  in  the 
latter  more  especially  in  the  seeds  (nuts,  almonds,  cocoa  nut,  poppy),  more  rarely 
in  the  pericarp  (olive)  or  in  the  root.  They  are  obtained  by  pressure,  melting,  or 
by  extracting  them  with  ether  or  boiling  alcohol.  They  contain  much  less  O 
than  the  carbohydrates,  such  as  sugar  and  starch ;  they  give  a  greasy  spot  on 
paper,  and  when  shaken  with  colloid  substances,  such  as  albumm,  they  yield  an 
emulsion.  When  treated  with  superheated  steam,  or  with  certain  ferments 
(p.  507,  c),  they  take  up  water  and  yield  glycerine  and  fatty  acids,  and  if  the  latter 
be  volatile  they  have  a  rancid  odour.  Treated  with  caustic  alkalies  they  also 
take  up  water,  and  are  decomposed  into  glycerine  and  fatty  acids;  the  fatty  acid 
unites  with  the  alkali  and  forms  a  soap,  while  glycerine  is  set  free.  The  soap- 
Bolutiou  dissolves  fats. 


FATS. 


509 


Glycerine  is  a  tri-atomic  alcohol,  C3H5(OH)3,  and  unites  with  (1)  the  following 
mono-basic /a<<y  ncic?s  (those  occurring  in  the  body  are  printed  in  italics) : — 


1. 

Formic           acid,              C  Hg  Oo 

10. 

Capric 

acid. 

C10H20O2 

2. 

Acetic 

,,                 C2H2  O2 

11. 

Lauroslearic 

,, 

C12H24O2 

3. 

Propionic 

>>                 CaHc  O2 

12. 

Myristic 

!> 

C14H28O2 

4. 

Butyric 

C4H8  O2 

13. 

Palmitic 

>> 

C16H32O2 

[Isobutyric 

C4H8  O2] 

[Margaric 

)> 

C17H34O2, 

5. 

Valerianic 

,                 C5H10O2 

is  a  mixture  of  13  and  14.] 

6. 

Caproic 

.                 C6H12O2 

14. 

Stearic 

acid. 

C18H3CO2 

7. 

Oinanthylic 

C7H14O2 

15. 

Arachinic 

>> 

C20H40O2 

8. 

Caprylic 

,                        C8Hxg02 

16. 

Hyanic 

,, 

C25H50O2 

9. 

Pelargonic        , 

)                  C9H1802 

17. 

Cerotinic 

,, 

C27H54O2 

The  acids  form  a  homologous  series  with  the  formula  CnH2n-iO(OH).  With 
every  CH2  added  their  boiling  point  rises  19°.  Those  containing  most  carbon  are 
solid,  and  non-volatile ;  those  containing  less  C  (up  to  and  including  capric  acid) 
are  fluid  like  oil,  have  a  burning  acid  taste,  and  a  rancid  odour. 

The  earlier  members  of  the  series  may  be  obtained  by  oxidation  from  the  later, 
by  CH2  being  removed,  while  COo  and  HoO  are  formed;  thus,  butyric  acid  is 
obtained  from  propioiiic  acid. 

Nos.  13  and  14  are  found  in  human  and  animal  fat,  less  abundant  and  more 
inconstant  are  12,  11,  6,  8,  10,  4.  Some  occur  in  sweat,  and  in  milk  (p.  465). 
Many  of  them  are  developed  during  the  decomposition  of  albumin  and  gelatin. 
Most  of  the  above  (except  15-17)  occur  in  the  contents  of  the  large  intestine 
(p.  376). 

(2.)  Glycerine  also  unites  with  the  mono-basic  oleic  acid,  which  also  forms  a  series, 
whose  general  formula  is  CnHin  — 30(0H)  ;  and  they  all  contain  2H  less  than  the 
corresponding  members  of  the  fatty  acid  series.  The  corresponding  fatty  acids 
can  be  obtained  from  the  oleic  acid  series  and  vice  versd.  Oleic  acid  (olein-elainic 
acid),  C1SH34O2,  is  the  only  one  found  in  the  organism;  united  with  glycerme,  it 
forms  the  fluid  fat,  olein  (Gottlieb,  1846).  The  fat  of  new-born  children  contains 
more  glyceride  of  palmitic  and  stearic  acid  than  that  of  adults,  which  contains 
more  glyceride  of  oleic  acid  (L.  Langer).  Oleic  acid  also  occurs  united  with 
alkalies  (in  soaps),  and  (like  some  fatty  acids)  in  the  lecithins  (p.  36).  If  lecithin 
be  acted  on  with  barium  hydrate,  we  obtain  insoluble  stearic,  or  oleic,  or  palmitic 
acids  and  barium  oleate,  together  with  dissolved  neurin  and  baric  glycerin- 
phosphate.  It  appears  as  if  there  were  several  lecithins,  of  which  the  most 
abundant  are  the  one  with  stearic  acid  and  that  with  palmitin  -t-  oleic  acid  radicle 
(Diakonow). 

The  neutral  fats,  the  glycerides  of  fatty  acids,  and  of  oleic  acid,  are  triple 
ethers  of  the  tri-atomic  alcohol  glycerine. 

With  the  neutral  fats  may  be  associated  glycerin-phosphoric  acid,  an  acid 
glycerin-ether,  formed  by  the  union  of  glycerine  and  phosphoric  acid,  with  the 
giving  off  of  a  molecule  of  water  (CsHgPOg) ;  it  is  a  decomposition  product  of 
lecithin  (p.  36). 

(3.)  The  gly colic  acids — (acids  of  the  lactic  acid  series)  have  the  formula 
CaH2n-20(OH)2.  They  are  formed  by  oxidation  fi-om  the  fatty  acid  series  by  sub- 
stituting OH  (hydroxyl)  for  1  atom  of  H  of  the  fatty  acids.  Conversely,  fatty 
acids  may  be  obtained  from  the  glycolic  acids.  The  following  acids  of  this  series 
occur  in  the  body  : — 

(a.)  Carbonic  Acid  (oxy-formic  acid)  CO  (0H)2;  in  this  form,  however,  it  only 
makes  salts.     Free  carbonic  acid  or  carbon  dioxide  is  an  anhydride  of  the  same 

=  C02. 

.    (6.)  Olycolic  Acid  (oxy-acetic  acid),  C2H2O  (0H)2,  does  not  occur  free  in  the  body. 


510  ACIDS   AND   ALCOHOLS. 

One  of  its  compounds,  glycin  (glycocoU,  amidoacetic  acid,  or  gelatin-sugar),  occurs 
as  a  conjugate  acid,  viz.,  as  glycocholic  acid  in  the  bile  (p.  355),  and  as  hippuric 
acid  in  the  urine.     Glycin  exists  in  complex  combination  in  gelatin. 

(c.)  Lactic  Acid  (oxy-propionic  acid),  C3H4O  (0H)2,  occurs  in  the  body  in  two 
isomeric  forms — 1.  The  ethylidene-laciic  acid,  which  occurs  in  two  modifications — 
as  the  right  rotatory  sarcolactic  acid  (paralactic),  a  metabolic  product  of  muscle; 
and  as  the  ordinary  optically  inactive  product  of  "lactic  fermentation,"  which 
occurs  in  gastric  juice,  in  sour  milk  (sauerkraut,  acid  cucumber),  and  can  be 
obtained  by  fermentation  from  sugar  (p.  373).  2.  The  isomer,  ethylene-lactic  acid, 
occurs  in  the  watery  extract  of  muscles. 

{d.)  Leucic  acid  (oxy-caproic  acid),  C6H12O3,  does  not  occur  as  such,  but  only  in 
the  form  of  one  of  its  derivatives,  leucin  (amido-caproic  acid),  as  a  product  of  the 
metabolism  in  many  tissues,  and  is  formed  during  pancreatic  digestion  (p.  342). 
Leucic  acid  may  be  prepared  from  leucin,  and  glycolic  acid  from  glycin  by  the 
action  of  nitrous  acid. 

(4.)  Acids  of  the  Oxalic  Acid  or  Succinic  Acid  Series  having  the  formula, 

CnH2n-402  (0H)2,  are  bi-basic  acids,  which  are  formed  as  completely  oxidised 
products  by  the  oxidation  of  fatty  acids  and  glycolic  acid  (H2O  being  removed); 
and  it  is  important  to  note  their  origin  from  substances  rich  in  carbon,  e.g.,  fats, 
carbohydrates,  and  proteids. 

(a.)   Oxalic  Acid,  C2O2   (0H)2,    arises   from  the  oxidation  of  glycol,   glycin,  . 
cellulose,  sugar,  starch,  glycerine,  and  many  vegetable  acids — it  occurs  in  the 
urine  as  calcium  oxalate. 

(b.)  Succinic  Acid,  C4H4O2  (011)2,  ^^^  been  found  in  small  amount  in  animal 
solids  and  fluids ;  spleen,  liver,  thymus,  thyroid ;  in  the  fluids  of  echinococcus,  of 
hydrocephalus,  and  of  hydrocele,  and  more  abundantly  in  dog's  urine  after  fatty 
and  flesh  food ;  in  rabbit's  urine  after  feeding  with  yellow  turnips.  It  is  also 
formed  in  small  amount  during  alcoholic  fermentation  (p.  298). 

(5.)  Cholalic  Acids  in  the  bile  (p.  356)  and  in  the  intestine  (p.  367). 

(6.)  Aromatic  Acids — Benzoic  acid  ( =  phenyl-f ormic  acid)  occurs  in  urine 
united  with  glycin,  as  hippuric  acid  (see  Urine). 

Ill— Alcohols. 

Alcohols  are  those  bodies  which  originate  from  carbohydrates,  in  which  the 
radicle  hydroxyl  (HO)  is  substituted  for  one  or  more  atoms  of  H.     They  may  be 

Tpr  -1 

regarded  as  water,  tt  >-  0,  in  which  the  half  of  the  H  is  replaced  by  a  CH  com- 
pound.     Thus,  C2H6  (ethyl-hydrogen)  passes  into    ^  jf  r  0  (ethylic  alcohol). 

(o.)  Cholesterin,     ^^    t|  [-0,  is  a  true  mon-atomic  alcohol,  and  occurs  in  blood, 

yelk,  brain,  bile  (p.  358),  and  generally  in  vegetable  cells. 
OH 


{h.)  Glycerine,  C3H5  <  OH,  is  a  tri-atomic  alcohol.     It  occurs  in  neutral  fats 
(OH 
miited  with    fatty  acids    and    oleic  acid ;    it    is    formed  by  the   splitting-up  of 
neutral  fats  during  pancreatic  digestion  (p.  343),  and  during  the  alcoholic  fermen- 
tation (p.  298). 

(c. )  Phenol  ( =  phenylic  acid,  carbohc  acid,  oxybenzol,  p.  376). 

(d.)  Brenzkatechin  (=  dioxybenzol). 

(e.)  The  Sugars  are  closely  related  to  the  alcohols,  and  they  may  be  regarded 
as  polyatomic  alcohols.  Their  constitution  is  unknown.  Together  with  a  series 
of  closely-related  bodies  they  form  the  great  group  of  the  Carboliydrates>  some 
of  which  occur  in  the  animal  body,  while  others  are  widely  distributed  in  the 
vegetable  kingdom. 


CARBOHYDRATES.  611 


252-  The  Carbohydrates. 


These  substances,  which  occur  in  plants  and  animals,  have  received  their  name, 
because  in  addition  to  C  (at  least  G  atoms),  they  contain  H  and  O,  in  the  propor- 
tion in  which  these  occur  in  water.  They  are  all  solid,  chemically  indifferent, 
and  without  odour.  They  have  either  a  sweet  taste  (sugars),  or  can  be 
readily  changed  into  sugars  by  the  action  of  dilute  acids;  they  rotate  the  ray  of 
polarised  light  either  to  the  right  or  left;  as  far  as  their  constitution  is  concerned, 
they  may  be  regarded  as  fatty  bodies,  as  hexatomic  alcohols,  in  which  2H  are 
wanting. 

They  ai'e  divided  into  the  following  group: — 

I.  Division.    Glucoses  (CsHigOe)— (i)  Grape-sugar  (glucose,  dextrose,  or 

diabetic  sugar)  occurs  in  minute  quantities  in  the  blood,  chyle,  muscle  (?  liver), 
urine,  and  in  large  amount  in  the  urine  in  diabetes  mellitus  (p.  .352).  It 
is  formed  by  the  action  of  diastatic  ferments  upon  other  carbohydrates,  during 
digestion.  In  the  vegetable  kingdom,  it  is  extensively  distributed  in  the 
sweet  juices  of  many  fruits  and  flowers  (and  thus  it  gets  into  honey).  It 
is  formed  from  cane-sugar,  maltose,  dextrin,  glycogen,  and  starch,  by  boiling 
with  dilute  acids.  It  crystallises  in  warty  masses  with  one  molecule  of  water  of 
crystallisation;  unites  with  bases,  salts,  acids,  and  alcohols,  but  is  easily  decom- 
posed by  bases;  it  reduces  many  metallic  oxides  (p.  297).  Fresh  solutions  have  a 
rotatory  power  of  + 106°.  "Qj  fermentation  with  yeast,  it  splits  up  into  alcohol  and 
CO2  (p.  298) ;  with  decomposing  proteids,  it  splits  into  two  molecules  of  lactic 
acid  (p.  373) ;  the  lactic  acid  splits  up  under  the  same  conditions  in  alkaline 
solutions,  into  butyric  acid,  COg  and  H.  For  the  qualitative  and  quantitative 
estimation  of  glucose,  see  §  149  and  §  150.  In  alcoholic  solution,  it  forms  very 
insoluble  compounds  with  chalk,  barium,  or  potassium,  and  it  also  forms  a 
crystalline  compound  with  common  salt. 

(2.)  Galactose,  obtained  by  boiling  milk-sugar  (lactose)  with  dilute  mineral 
acids;  it  crystallises  readily,  is  very  fermentable,  and  gives  all  the  reactions  of 
glucose.  When  oxidised  with  nitric  acid  it  becomes  transformed  into  mucic  acid. 
Its  specific  rotatory  power  =  +  88 '08°. 

(3.)  Laevulose  (left-fruit-,  invert- or  mucin-sugar)  occurs  as  a  colourless  syrup  in 
the  acid-juices  of  some  fruits  and  in  honey;  is  non-crystallisable,  and  insoluble  in 
alcohol ;  specific  rotatory  j)ower  =  — 106°.  It  is  formed  normally  in  the  intestine 
(p.  370),  and  occurs  I'arely  as  a  pathological  product  in  urine. 

II.  Division  contains  carbohydrates  with  the  formula  C12H22O11,  and  which 
may  be  regarded  as  anhydrides  of  the  first  division — (1)  Milk-SUgar  or  lactOSe 
occurs  only  in  milk,  crystallises  in  cakes  (with  one  molecule  of  water)  from  the 
syrupy  concentrated  whey;  it  rotates  polarised  light  to  the  right  = -^  59 "3,  and  is 
much  less  soluble  in  water  and  alcohol  than  grape-sugar.  When  boiled  with  dilute 
mineral  acids  it  passes  into  galactose,  and  can  be  directly  transformed  into  lactic 
acid  only  by  fermentation;  the  galactose,  however,  is  capable  of  undergoing  the 
alcoholic  fermentation  with  yeast  (Koumis  preparation,  p.  468).  For  its  quantita- 
tive estimation,  see  Milk. 

(2.)  Maltose  (Ci2H220ii)-f  HjO  (O'Sullivan)  has  one  molecule  of  water  less 
than  grape-sugar  (C12H24O12),  is  formed  during  the  action  of  a  diastatic  ferment, 
such  as  saliva  upon  starch  (p.  294);  is  soluble  in  alcohol,  right  rotatory  power  = 
150°,  it  is  crystalline,  while  its  reducing  power  is  only  two-thirds  that  of  dextrose. 

(3.  Saccharose  (cane-sugar)  occurs  in  sugar-cane  and  some  plants,  it  does 
not  reduce  solutions  of  copper,  is  insoluble  in  alcohol,  is  right  rotatory,  and  not 
capable  of  fermentation.  When  boiled  with  dilute  acids,  it  becomes  changed 
into  a  mixture  of  easily  fermentable  glucose  (right-rotatory)  and  laevulose 
(invert-sugar)  which  ferments  with  difficulty  and  is  left-rotatory  (p.  370).  When 
oxidised  with  nitric  acid,  it  passes  into  glucic  acid  and  oxalic  acid.) 


512 


CARBOHYDRATES. 


(4.  Melitose,  from  Eucalyptus-manna;  Melezitose,  from  Larcli-manna ; 
Trehalose  (Mycose),  from  Ergot ;  all  right-rotatory,  and  do  not  reduce  alkaline 
cupric  solutions.) 

III.  Division,  contains  carbohydrates  with  the  formula,  CeHioOs,  which  may 
be  regarded  as  anhydrides  of  the  second  division. 

1.  Glycogen,  with  a  rotatory  power  of  211°  (Bohm  and  Hofl&nann,  Klilz),  does 
not  reduce  cupric  oxide.  It  occurs  in  the  liver  (p.  350),  muscles,  many  embryonic 
tissues,  the  embryonic  area  of  the  chick  (Kiilz),  in  normal  and .  pathological 
epitheUum  (Schiele),  and  according  to  Pavy,  in  the  spleen,  pancreas,  kidney,  ovum, 
brain  and  blood,  together  with  a  small  amount  of  glucose.  It  also  occurs  in  the 
oyster  and  some  of  the  molluscs  (Bizio). 

2.  Dextrin  was  discovered  by  Limpricht  in  the  muscles  of  the  horse.  It  is 
right-rotatory  =  +  138°,  soluble  in  water  and  forms  a  very  sticky  solution,  from 
which  it  is  precipitated  by  alcohol  or  acetic  acid  ;  it  is  tinged  slightly  red  with 
iodine.  It  is  formed  in  roasted  starch,  (hence  it  occurs  in  large  quantity  in  the 
crust  of  bread — see  Bread,  p.  472),  by  dilute  acids,  and  in  the  body  by  the  action 
of  ferments  (p.  294).  It  is  formed  from  cellulose  by  the  action  of  dilute  sulphuric 
acid.     It  occurs  in  beer,  and  is  found  in  the  juices  of  most  plants. 

(3.    Amylum    or    Starch 

e  occurs  in  the  "  mealy"  parts  of 

many  plants,  is  formed  within 
vegetable  cells,  and  consists  of 
concentric  layers  with  an  ex- 
centric  nucleus  (Fig.  176,  B) 
The  diameter  of  starch  grains 
varies  greatly  with  the  plant 
from  which  they  are  derived. 
At  72°C.  it  swells  up  in  water 
and  forms  mucilage ;  in  the 
cold,  iodine  colours  it  blue. 
Starch  grains  always  contain 
more  or  less  cellulose  and  a  sub- 
stance which  is  coloured  red 
with  iodine  {erythrogranulose) 
(see  p.  294).  It  and  glycogen 
are  transformed  into  dextrose  by 
certain  digestive  ferments  in  the 
saliva,  pancreatic  and  intestinal 
juices,  and  artificially  by  boiling 
with  dilute  sulphuric  acid. ) 
(4.  Gum  occurs  in  vegetable  juices  (specially  in  acacise  and  mimosse),  is  partly 
soluble  in  water  (arabin),  partly  swells  up  like  mucin  (bassorin).  Alcohol  pre- 
cipitates it. ) 

(5.  Inulin,  a  crystalline  powder  occurring  in  the  root  of  chicory,  dandelion,  and 
specially  in  the  bulbs  of  the  dahlia;  it  is  not  coloured  blue  by  iodine.) 

(6.  Lichenin  occurs  in  the  intercellular  substance  of  Iceland  moss  (Cetraria 
islandica)  and  algae;  is  transformed  into  glucose  by  dilute  sulphuric  acid.) 

(7.  Paramylum  occurs  in  the  form  of  granules  resembling  starch,  in  the  infua- 
orian,  Euglena  viridis. ) 

(8.  Cellulose  occurs  in  the  cell-walls  of  all  plants  (in  the  exo-skeleton  of 
arthropoda,  and  the  skin  of  snakes) ;  soluble  only  in  ammonio-cupric  oxide ;  ren- 
dered blue  by  sulphuric  acid  and  iodine.  Boiled  with  dilute  sulphuric  acid,  it 
yields  dextrin  and  glucose.  Concentrated  nitric  acid  mixed  with  sulphuric  acid 
changes  it  (cotton)  into  nitro-cellulose  (gun  cotton)  C6H7(N02)30fi,  which  dissolves 
in  a  mixture  of  ether  and  alcohol  and  forms  collodion.) 


Fig.  176. 
Section  of  a  wheat  grain — d,  starch-corpuscles 
within  vegetable  cells;  B,  starch-corpuscles 
with  concentric  markings   (See  also  Fig. 
173). 


DERIVATIVES   OF  AMMONIA  AND   THEIR  COMPOUNDS.  513 

(9.  Tunicin  is  a  substance  resembling  cellulose,  and  occurs  in  the  integument  of 
the  tunicata  or  ascidians. ) 

IV.  Pivision  contains  the  carbohydrates  which  do  not  ferment. 

1.  Inosit  ( phaseo-mannit,  mus(?le-sugar)  occurs  in  muscle  (Scherer),  lung,  liver, 
spleen,  kidney,  brain  of  ox,  human  kidney;  pathologically  in  urine  and  the  fluid 
of  echinococcus.  In  the  vegetable  kingdom,  in  beans  (leguminoste),  and  the  juice 
of  the  grape.  It  is  an  isomer  of  grape-sugar;  optically  it  is  inactive,  crystallises 
in  warts  with  two  molecules  of  water,  in  long  monoclinic  crystals ;  it  has  a  sweet 
taste,  is  insoluble  in  water,  does  not  give  Trommer's  reaction,  is  capable  of  under- 
going onli/  the  sarcolactic  acid  fermentation.  (Nearly  alliedare  Sorbin  from  sorbic 
acid — Scyllit  from  the  intestines  of  the  hag-fish  and  skate — and  Enkalyn  arising 
from  the  fermentation  of  melitose.) 

IV.— Derivatives  of  Ammonia  and  their  Compounds. 

The  ammonia  derivatives  are  obtained  from  the  proteids,  and  are  decomposition 
products  of  their  metabolism. 

(1.)  AnoineS)  '•^•>  compound  ammonias  which  can  be  obtained  from  ammonia 
(NH3),  or  from  ammonium-hydroxide  (NH4  -  OH),  by  replacing  one  or  all  the  atoms 
of  H  by  groups  of  cai'bohydrates  (alcohol  radicals).     The  amine  derived  from 
one  molecule  of  ammonia  is  called  monamine.     We  are  only  acquainted  with 
H  ^  CH3) 

Hy  N      Methylamine  and  Tri-Methylamine       CHg^  N, 
CH3)  CH3) 

as  decomposition  products  of  cholin  (neurin)  and  of  kreatin.     Netirin  occurs  in 
lecithin  in  a  very  complex  combination  (see  Lecithin  under  Fatsf,  and  also  p.  36). 

(2.)  Amides,  i.e.,  derivatives  of  acids,  which  ha\  e  exchanged  the  hydroxyl 
(HO)  of  the  acids  for  NHg.  Urea,  COlNHo),,  the  biamid  of  CO2,  is  the  chief  end- 
product  of  the  metabolism  of  the  nitrogenous  constituents  of  our  bodies  (see 
Urine).  Carbonic  acid  containing  water  =  C0(0H)2;  in  it  both  OH  are  replaced 
by  NH2— thus  we  get  CO(NH2)2>  urea, 

(30  Amido-acidSj  i.e.,  nitrogenous  compounds  (p.  341),  which  show  partly  the 
character  of  an  acid  and  partly  that  of  a  weak  base,  in  which  the  atoms  of  H  of 
the  acid  radicle  are  replaced  by  NH2,  or  by  the  substituted  ammonia  groups. 

(«•)  Glycin — (p.  355),  (or  amido-acetic  acid,  gl3'cocoll,  gelatin-sugar  is  formed 
by  boiling  gelatin  with  dilute  sulphuric  acid.  It  has  a  sweet  taste  (gelatin-sugar), 
behaves  as  a  weak  acid,  but  also  unites  with  acids  as  an  amine-base.  It  occurs  as 
glycin  -f  benzoic  acid  =  hippuric  acid  in  urine  ;  and  also  as  glycin  -f  cholalic  acid  = 
glyco-cholic  acid  m  bile  (p.  355).  (b.)  Leucin — (P-  341)  =  amido-caproic  acid, 
(c.)  Serin — (=?  amido-lactic  acid)  obtained  from  silk-gelatin,  {d.)  Asparaginic 
acid — (amido-succinic  acid) ;  and  (?.)  Glutaminic  acid  obtained  by  tlie  splitting 
up  of  proteids  (p.  342).  Other  amido-acids  are  — (/.)  Cystin  =  amido-lactic  acid  in 
which  0  is  replaced  by  S  (see  Urine).  {(/.)  Taurin— (p.  355),  amido-ethyl-sul- 
phuric  acid  occurs  (except  in  certain  glands)  chiefly  in  combination  with  cholalic 
acid,  as  taurocliolic  acid  in  bile.  Tyrosin  (parahydro-oxyphenyl-amido-propionic 
acid),  an  amido-acid  of  unknown  constitution,  occurs  along  with  leucin  during 
pancreatic  digestion  (p.  341),  is  a  decomposition  product  of  proteids,  and  occurs 
plentifully  in  the  urine  in  acute  yellow  atrophy  of  the  liver. 

To  the  amido-acids  are  related— (a.)  Kreatin  in  muscle,  brain,  blood,  urine, 
regarded  as  methyl-uramido-acetic  acid  (C4H9X3O2).  It  has  been  prepared  arti- 
ficially. When  boiled  with  baryta  water,  it  takes  up  H2O,  and  splits  into  urea ; 
and  (b.)  Sarkosin  (C3H7NO2),  methyl-amido-acetic  acid.  When  boiled  with 
water,  heated  with  strong  acids,  in  the  presence  of  putrefying  substances, 
kreatin  gives  off  water,  and  is  changed  into  kreatinin  (€4117X30).  This  strong 
base  can  be  rechanged  by  alkalies  into  kreatin. 

33 


514  HISTORICAL. 

(4)    Ammonia   Derivatives  of  Unknown    Constitution.— CTV-jc    add, 

allantoin  (see  Urine)  is  formed  by  the  oxidation  of  uric  acid  by  means  of 
potassium  permanganate ;  cyanuric  acid  in  dog's  urine ;  inosinic  acid  in  muscle; 
gunnin  in  traces  in  the  liver  and  pancreas,  in  guano,  the  excrements  of  spiders,  in 
the  skin  of  amphibia  and  reptiles,  in  the  silver  sheen  of  many  fishes  (A.  Ewald  and 
Krukenberg);  by  oxidation  it  yields  urea;  liypoxantliin  or  sarkin  occurs  along  with 
xanthin  in  many  organs  and  in  urine.  Kossel  prepared  hypoxanthin  from  nuclein 
by  prolonged  boiling  of  the  latter.  It  may  be  obtained  from  fibrin  by  putrefac- 
tion, by  gastric  and  pancreatic  digestion,  and  by  dilute  acids  (Salomon,  H.  Krause, 
Chittenden) ;  xanthin  is  prepared  by  oxidation  from  hypoxanthin.  It  occurs  very 
rarely  in  the  form  of  a  urinary  calculus.  Paraxanthin  in  urine,  and  a  similar  body 
carnin  in  flesh  (§  233). 

Aromatic  Substances. 

1.  Monatomic  phenols — (a)  Phenol  (hydroxyl  of  benzol)  in  the  intestine 
(p.  3i6).  Phenylsulphuric  acid  in  urine.  (6)  Kresol  in  the  form  of  orthokresol 
and  parokresol,  united  with  sulphuric  acid,  occur  in  urine.  2.  Diatomic  phenol  S 
— (a)  Benzkatechin  united  with  sulphuric  acid  in  urine.  3.  AromatiC  OXyacids 
— (a)  Hydroparacumaric  acid;  (6)  Paraoxyphenylacetic  acid  in  urine.  4.  Indol 
and  sTcatol  in  the  intestine  (p.  376),  conjoined  with  sulphuric  acid  in  urine. 

253.  Historical. 

According  to  Aristotle,  the  organism  requires  food  for  three  purposes — for 
growth,  for  the  production  of  heat,  and  to  compensate  for  the  loss  of  the  bodily 
excreta.  The  formation  of  heat  takes  place  in  the  heart  by  a  process  of  concoc- 
tion, the  heat  so  formed  being  distributed  to  all  parts  of  the  body  by  means  of  the 
blood,  while  the  respiration  is  regarded  as  an  act  whereby  the  body  is  cooled. 
Galen  accepted  this  view  in  a  somewhat  modified  form;  according  to  him,  the 
metabolic  processes  may  be  compared  to  the  processes  going  on  in  a  lamp;  the  blood 
represents  the  oil;  the  heart,  the  wick;  the  lungs,  the  fanning  apparatus. 
According  to  the  view  of  the  iatrochemical  school  (van  Helmont),  the  metabolic 
processes  of  the  body  are  fermentations,  whereby  the  food  is  mixed  with  the  juices 
of  the  body.  Since  the  middle  of  the  seventeenth  century  (Boyle),  the  knowledge 
of  the  metabolic  processes  has  followed  the  development  of  chemistry.  A.  v. 
Haller  regarded  heat  as  due  to  chemical  processes— the  food  continually  supplying 
the  waste  which  is  excreted  from  the  body.  After  the  discovery  of  oxygen  (1774, 
by  Priestley  and  Scheele),  Lavoisier  formulated  the  theory  of  combustion  in  the 
lungs,  whereby  carbonic  acid  and  water  were  formed.  Mitscherlich  compared  the 
decomposition-processes  in  the  living  body  with  putrefactive  processes.  Magendie 
was  the  first  to  emphasise  the  difference  between  nitrogenous  and  non-nitrogenous 
foods,  and  he  showed  that  the  latter  alone  were  not  able  to  support  Ufe.  Even 
gelatin  alone  is  not  sufiicient  for  this  purpose. 

The  greatest  advance  in  the  theory  of  nutrition  was  made  by  J.  v.  Liebig,  who 
laid  the  foundation  of  our  present  knowledge  of  this  subject.  According  to  Liebig, 
foods  may  be  divided  into  two  classes,  viz.,  the  "plastic,"  suitable  for  the 
construction  of  the  organism,  and  the  "respiratory"  for  the  maintenance  of  the 
temperature ;  to  the  former  class  he  referred  the  albuminates  or  proteids,  to  the 
latter,  the  non-nitrogenous  carbohydrates  and  fats. 

Amongst  recent  observers,  the  Munich  School,  as  represented  by  v.  Bischoff, 
V.  Pettenkofer  and  v.  Voit,  has  done  most  to  give  us  an  exact  knowledge  of  this 
department  of  physiology. 


COLUMBIA  UNIVERSITY 

rhis  book  is  due  on  the  date  indicated  below,  or  at  the 
expiration  of  a  definite  period  after  the  date  of  borrowing, 
as  provided  by  the  rules  of  the  Library  or  by  special  ar- 
rangement with  the  Librarian  in  charge. 

DATE  BORROWED 

DATE  DUE 

DATE  BORROWED 

DATE  DUE 

C2e(638)M30 

QP34 
Landois 


